InSight (Interior Exploration using Seismic Investigations, Geodesy and Heat Transport)
InSight is a NASA minisatellite lander mission, designed to give the Red Planet its first thorough checkup since it formed 4.5 billion years ago. It is the first outer space robotic explorer to study in-depth the "inner space" of Mars: its crust, mantle, and core. Studying Mars' interior structure answers key questions about the early formation of rocky planets in our inner solar system - Mercury, Venus, Earth, and Mars - more than 4 billion years ago, as well as rocky exoplanets. InSight also measures tectonic activity and meteorite impacts on Mars today. 1) 2) 3) 4) 5)
The lander uses cutting edge instruments, to delve deep beneath the surface and seek the fingerprints of the processes that formed the terrestrial planets. It does so by measuring the planet's "vital signs": its "pulse" (seismology), "temperature" (heat flow), and "reflexes" (precision tracking). This mission is part of NASA's Discovery Program for highly focused science missions that ask critical questions in solar system science.
JPL, a division of Caltech in Pasadena, California, manages the InSight Project for NASA's Science Mission Directorate, Washington. Lockheed Martin Space, Denver, built the spacecraft. InSight is part of NASA's Discovery Program, which is managed by NASA's Marshall Space Flight Center in Huntsville, Alabama.
First Interplanetary CubeSat: The rocket that will loft InSight beyond Earth will also launch a separate NASA technology experiment: two mini-spacecraft called MarCO (Mars Cube One). These suitcase-sized CubeSats will fly on their own path to Mars behind InSight. Their objective is to relay back InSight data as it enters the Martian atmosphere and lands. It will be a first test of miniaturized CubeSat technology at another planet, which researchers hope can offer new capabilities to future missions.
If successful, the MarCos could represent a new kind of data relay to Earth, getting news of a safe landing — and any potential problems — sooner. InSight’s success is independent of its co-passengers.
InSight Science Goals: The InSight mission seeks to uncover how a rocky body forms and evolves to become a planet by investigating the interior structure and composition of Mars. The mission will also determine the rate of Martian tectonic activity and meteorite impacts. The InSight mission has two major goals, each with several science investigations, designed to help uncover the process that shaped all of the rocky planets in the inner solar system.
1) To understand how rocky planets formed and evolved, InSight will study the interior structure and processes of Mars by determining:
- The size of the core, what it is made of, and whether it is liquid or solid.
- The thickness and structure of the crust.
- The structure of the mantle and what it is made of.
- How warm the interior is and how much heat is still flowing through.
2) InSight will figure out just how tectonically active Mars is today, and how often meteorites impact it. For this, it will measure:
- How powerful and frequent internal seismic activity is on Mars, and where it is located within the structure of the planet.
- How often meteorites impact the surface of Mars.
Figure 1: Left: Artist’s rendition showing the inner structure of Mars. The topmost layer is known as the crust, underneath it is the mantle, which rests on a solid inner core. Right: Measuring the pulse of Mars by determining the level of tectonic activity (impact of meteorites) on Mars (image credit: NASA/JPL-Caltech)
Why Mars? — Previous missions to Mars have investigated the surface history of the Red Planet by examining features like canyons, volcanoes, rocks and soil. However, signatures of the planet's formation can only be found by sensing and studying its "vital signs" far below the surface.
In comparison to the other terrestrial planets, Mars is neither too big nor too small. This means that it preserves the record of its formation and can give us insight into how the terrestrial planets formed. It is the perfect laboratory from which to study the formation and evolution of rocky planets. Scientists know that Mars has low levels of geological activity. But a lander like InSight can also reveal just how active Mars really is.
Starting next year, scientists will get their first look deep below the surface of Mars. That's when NASA will send the first robotic lander dedicated to exploring the planet's subsurface. InSight will study marsquakes to learn about the Martian crust, mantle and core. 6)
Doing so could help answer a big question: how are planets born? - Seismology, the study of quakes, has already revealed some of the answers here on Earth, said Bruce Banerdt, Insight's principal investigator at NASA/JPL (Jet Propulsion Laboratory), Pasadena, California. But Earth has been churning its geologic record for billions of years, hiding its most ancient history. Mars, at half the size of Earth, churns far less: it's a fossil planet, preserving the history of its early birth.
"During formation, this ball of featureless rock metamorphosed into a diverse and fascinating planet, almost like caterpillar to a butterfly," Banerdt said. "We want to use seismology to learn why Mars formed the way it did, and how planets take shape in general."
A Planetary CT (Computed Tomography) Scan: When rocks crack or shift, they give off seismic waves that bounce throughout a planet. These waves, better known as quakes, travel at different speeds depending on the geologic material they travel through.
Seismometers, like InSight's SEIS instrument, measure the size, frequency and speed of these quakes, offering scientists a snapshot of the material they pass through. "A seismometer is like a camera that takes an image of a planet's interior," Banerdt said. "It's a bit like taking a CT scan of a planet."
Mars' geologic record includes lighter rocks and minerals — which rose from the planet's interior to form the Martian crust — and heavier rocks and minerals that sank to form the Martian mantle and core. By learning about the layering of these materials, scientists can explain why some rocky planets turn into an "Earth" rather than a "Mars" or "Venus" — a factor that is essential to understanding where life can appear in the universe.
A Fuzzy Picture: Each time a quake happens on Mars, it will give InSight a "snapshot" of the planet's interior. The InSight team estimates the spacecraft will see between a couple dozen to several hundred quakes over the course of the mission. Small meteorites, which pass through the thin Martian atmosphere on a regular basis, will also serve as seismic "snapshots."
"It will be a fuzzy picture at first, but the more quakes we see, the sharper it will get," Banerdt said.
One challenge will be getting a complete look at Mars using only one location. Most seismology on Earth takes measurements from multiple stations. InSight will have the planet's only seismometer, requiring scientists to parse the data in creative ways. "We have to get clever," Banerdt said. "We can measure how various waves from the same quake bounce off things and hit the station at different times."
Moonquakes and Marsquakes: InSight won't be the first NASA mission to do seismology. The Apollo missions included four seismometers for the Moon. Astronauts exploded mortar rounds to create vibrations, offering a peek about 100 meters under the surface. They crashed the upper stages of rockets into the Moon, producing waves that enabled them to probe its crust. They also detected thousands of genuine moonquakes and meteorite impacts.
The Viking landers attempted to conduct seismology on Mars in the late 1970s. But those seismometers were located on top of the landers, which swayed in the wind on legs equipped with shock absorbers. "It was a handicapped experiment," Banerdt said. "I joke that we didn't do seismology on Mars — we did it three feet above Mars."
InSight will measure more than seismology. The Doppler shift from a radio signal on the lander can reveal whether the planet's core is still molten; a self-burrowing probe is designed to measure heat from the interior. Wind, pressure and temperature sensors will allow scientists to subtract vibrational "noise" caused by weather. Combining all this data will give us the most complete picture of Mars yet.
JPL, a division of Caltech in Pasadena, manages the InSight Project for NASA's Science Mission Directorate, Washington. Lockheed Martin Space in Denver, Colorado, built and tested the spacecraft. InSight is part of NASA's Discovery Program, which is managed by NASA's Marshall Space Flight Center in Huntsville, Alabama.
NASA's InSight lander opens a window into the "inner space" of Mars. Its instruments peer deeper than ever into the Martian subsurface, seeking the signatures of the processes that shaped the rocky planets of the inner Solar System, more than four billion years ago. InSight's findings are expected to shed light on the formation of Mars, Earth, and even rocky exoplanets.
The lander builds on the proven design of NASA's Mars Phoenix lander. InSight's over 2.4-meter-long robotic arm lifts a seismometer and heat-flow probe from the deck and places them on the surface. The camera on the arm will provide color 3D views of the landing site, instrument placement, and activities. Sensors measure weather and magnetic field variations.
The state-of-the art robotic arm was built by SSL Robotics in Pasadena, CA, previously known as MDA US Systems and now part of Maxar Technologies. The robotic arm will use its five nimble fingers to remotely grasp the lander’s instruments and carefully place each piece of hardware onto the Martian surface.
Table 1: Specifications of the InSight Lander
Figure 2: An artist's rendition of the InSight lander operating on the surface of Mars (image credit: NASA/JPL-Caltech)
The spacecraft is the protective "spaceship" that protects the lander during its travel between Earth and Mars. The spacecraft is separate from the launch vehicle that carries the spacecraft and the lander outside of Earth's atmosphere and gravitational pull. The spacecraft includes the mechanical units that safely maneuver the lander through the Martian atmosphere to a landing on Mars.
The three major parts that make-up the InSight spacecraft are:
• Cruise Stage: The Cruise Stage encapsulates the lander and its landing system for travel between Earth and Mars. It includes an aeroshell, which consists of a backshell and a heat shield that protects the lander from harsh forces encountered during launch and landing.
• EDL (Entry, Descent, and Landing) System: The EDL system includes the aeroshell, parachute, and descent vehicle that lower the lander to the Martian surface. The final touchdown is enabled by shock-absorbing legs.
• Lander: InSight’s stationary lander is constructed to deploy sensitive instruments on the surface of Mars from where they can directly sense the planets "vital signs."
Lockheed Martin is the InSight prime contractor and is responsible for the complete spacecraft system – cruise stage, aeroshell and the lander itself. Based on a proven spacecraft design from the successful 2007 Phoenix mission, InSight will incorporate the latest avionics technology as well as advanced science instruments. 7) 8)
Figure 3: NASA's InSight Mars lander spacecraft in a Lockheed Martin clean room in Littleton, CO (image credit: NASA/JPL-Caltech/Lockheed Martin)
Figure 4: Illustration of spacecraft and lander components (image credit: NASA/JPL)
Insight Development status
• May 4, 2018: ESA's deep space ground stations in Australia and South America will track the InSight spacecraft on NASA’s behalf as it begins its cruise to the Red Planet. 9)
- Set to be launched from Vandenberg Air Force Base in California on an Atlas V at 1105 UTC on 5 May, InSight will bring a lander to Mars to study its interior, with equipment to measure internal heat and detect ‘marsquakes’. InSight’s 485 million km journey to Mars will take about six months, beginning soon after it separates from its launcher in Earth orbit.
- Five hours after launch, ESA’s deep space ground station at New Norcia in Western Australia, will pick up the signal from InSight. It will maintain contact as a ‘hot backup’ at the same time as NASA’s own Deep Space Network ground station at Canberra, over on the easterly side of the continent.
- Once Canberra loses contact, the 35 m dish antenna at New Norcia will maintain contact with the mission until it vanishes under the horizon. ESA’s second southern-hemisphere deep space ground station at Malargüe in Argentina will pick up the contact two and a half hours after that.
• April 6, 2018: In the early morning hours of May 5, millions of Californians will have an opportunity to witness a sight they have never seen before - the historic first interplanetary launch from America's West Coast. On board the 57.3 m United Launch Alliance Atlas V rocket will be NASA's InSight spacecraft, destined for the Elysium Planitia region located in Mars' northern hemisphere. 10)
Figure 5: NASA's InSight to Mars undergoes final preparations at Vandenberg AFB, CA, ahead of its May 5 launch date Image credit: NASA/JPL-Caltech)
• March 23, 2018: Scientists in Germany are working hard to ensure NASA's next Mars mission, the Insight mission, gets the most accurate data possible. Researchers are currently testing a replica of the probe's SEIS (Seismic Experiment for Interior Structure) instrument package, a combination of six seismometers that will be used to study geologic structures deep beneath the Martian surface. The testing will help scientists back in the United States properly calibrate the real SEIS instrument package. 11) 12)
- The testing is being carried out at the Joint Geoscientific Observatory, or BFO (Black Forest Observatory), in Schiltach, by a team of researchers from KIT (Karlsruhe Institute of Technology) and Stuttgart University. The combination of three short-period seismometers and three broadband seismometers allows the instrument package to target a wide range of frequencies.
- "Ground movement in vertical and two horizontal directions can be measured," BFO researcher Rudolf Widmer-Schnidrig said in a news release.
- The instruments were developed by engineers in France and the United States, and have previously been tested at BFO. Earlier tests focused on a pair of short-period seismometers, while a single broadband seismometer is the focus of the latest round of testing. All the tests will offer a baseline under optimal conditions against which scientists can compare the data returned by the real instrument package.
- "At the BFO, we have excellent measurement conditions. Seismic noise is low. The seismometers supply data with the lowest noise worldwide," Widmer-Schnidrig said.
- Scientists are testing the instruments inside measurement chambers installed in the tunnel system of a former ore mine in the Black Forest. At 150 m beneath Earth's surface, the testing chambers protect instruments from air pressure and temperature fluctuation, as well as interference from communication systems.
Figure 6: Researchers at Germany's BFO (Black Forest Observatory) are calibrating a replica of the SEIS instrument package on NASA's InSight probe(image credit: KIT)
• February 28, 2018: NASA's InSight spacecraft has arrived at VAFB (Vandenberg Air Force Base) in central California to begin final preparations for a launch this May. The spacecraft was shipped from Lockheed Martin Space, Denver, today and arrived at VAFB. InSight will be the first mission to look deep beneath the Martian surface, studying the planet's interior by listening for marsquakes and measuring the planet's heat output. It will also be the first planetary spacecraft to launch from the West Coast. 13)
Figure 7: Personnel supporting NASA's InSight mission to Mars load the crated InSight spacecraft into a C-17 cargo aircraft at Buckley Air Force Base, Denver, for shipment to Vandenberg Air Force Base, California (image credit: NASA/JPL)
• February 22, 2018: NASA's Mars InSight lander team is preparing to ship the spacecraft from Lockheed Martin Space in Denver, where it was built and tested, to Vandenberg Air Force Base in California, where it will become the first interplanetary mission to launch from the West Coast. The project is led by NASA's Jet Propulsion Laboratory in Pasadena, California. 14)
- InSight is the first mission to study the deep interior of Mars. InSight will take the "vital signs" of Mars: its pulse (seismology), temperature (heat flow), and its reflexes (radio science). It will be the first thorough check-up since the planet formed 4.5 billion years ago.
- InSight will teach us about planets like our own. InSight's team hopes that by studying the deep interior of Mars, we can learn how other rocky planets form. Earth and Mars were molded from the same primordial stuff more than 4 billion years ago, but then became quite different. Why didn't they share the same fate?
- InSight will try to detect marsquakes for the first time. One key way InSight will peer into the Martian interior is by studying motion underground — what we know as marsquakes. NASA has not attempted to do this kind of science since the Viking mission. Both Viking landers had their seismometers on top of the spacecraft, where they produced noisy data. InSight's seismometer will be placed directly on the Martian surface, which will provide much cleaner data.
• January 23, 2018: NASA's next mission to Mars passed a key test, extending the solar arrays that will power the InSight spacecraft once it lands on the Red Planet this November. 15)
- The fan-like solar panels are specially designed for Mars' weak sunlight, caused by the planet's distance from the Sun and its dusty, thin atmosphere. The panels will power InSight for at least one Martian year (two Earth years) for the first mission dedicated to studying Mars' deep interior.
Figure 8: This photo shows the completion of one solar panels during the InSight deployment test (image credit: NASA, Lockheed Martin)
Figure 9: The test took place at Lockheed Martin Space just outside of Denver, where InSight was built and has been undergoing testing ahead of its launch (image credit: NASA, Lockheed Martin)
• November 3, 2017: Last month, NASA invited members of the public to send their names to Mars. And the public responded loud and clear. More than 1.6 million people signed up to have their names etched on a microchip that will be carried on NASA's upcoming InSight mission, which launches in May of 2018. 16)
- NASA's Jet Propulsion Laboratory in Pasadena, California, reopened the opportunity after it proved successful in 2015. During that open call, nearly 827,000 names were collected for a microchip that now sits on top of the robotic InSight lander.
- The grand total once a second microchip is added in early 2018 will be 2,429,807 names. Space enthusiasts who signed up this last round shared their downloadable "boarding passes" on social media, complete with the total number of flight miles they've collected by participating in engagement initiatives for other Mars missions.
• September 13, 2017: NASA scientists have found evidence that Mars’ crust is not as dense as previously thought, a clue that could help researchers better understand the Red Planet’s interior structure and evolution. A lower density likely means that at least part of Mars’ crust is relatively porous. At this point, however, the team cannot rule out the possibility of a different mineral composition or perhaps a thinner crust. 17)
- The researchers mapped the density of the Martian crust, estimating the average density is 2,582 kg/m3. That’s comparable to the average density of the lunar crust. Typically, Mars’ crust has been considered at least as dense as Earth’s oceanic crust, which is about 2,900 kg/m3.
- The new value is derived from Mars’ gravity field, a global model that can be extracted from satellite tracking data using sophisticated mathematical tools. The gravity field for Earth is extremely detailed, because the data sets have very high resolution. Recent studies of the Moon by NASA’s GRAIL (Gravity Recovery and Interior Laboratory) mission also yielded a precise gravity map.
- The data sets for Mars don’t have as much resolution, so it’s more difficult to pin down the density of the crust from current gravity maps. As a result, previous estimates relied more heavily on studies of the composition of Mars’ soil and rocks.
Figure 10: A new map of the thickness of Mars’ crust shows less variation between thicker regions (red) and thinner regions (blue), compared to earlier mapping. This view is centered on Valles Marineris, with the Tharsis Montes near the terminator to its west. The map is based on modeling of the Red Planet’s gravity field by scientists at NASA/GSFC in Greenbelt, Maryland. The team found that globally Mars’ crust is less dense, on average, than previously thought, which implies smaller variations in crustal thickness (image credit: NASA/Goddard/UMBC/MIT/E. Mazarico)
• August 26, 2017: Preparation of NASA's next spacecraft to Mars, InSight, has ramped up this summer, on course for launch next May from Vandenberg Air Force Base in central California — the first interplanetary launch in history from America's West Coast. 18)
- Lockheed Martin Space Systems is assembling and testing the InSight spacecraft in a clean room facility near Denver. "Our team resumed system-level integration and test activities last month," said Stu Spath, spacecraft program manager at Lockheed Martin. "The lander is completed and instruments have been integrated onto it so that we can complete the final spacecraft testing including acoustics, instrument deployments and thermal balance tests." InSight is the first mission to focus on examining the deep interior of Mars. Information gathered will boost understanding of how all rocky planets formed, including Earth.
Figure 11: The Mars lander portion of NASA's InSight spacecraft is lifted from the base of a storage container in preparation for testing, in this photo taken June 20, 2017, in a Lockheed Martin clean room facility in Littleton, Colorado (image credit: NASA/JPL-Caltech, Lockheed Martin)
• September 2, 2016: NASA is moving forward with a spring 2018 launch of its InSight mission to study the deep interior of Mars, following final approval this week by the agency’s Science Mission Directorate. 19)
- The InSight mission was originally scheduled to launch in March of this year, but NASA suspended launch preparations in December due to a vacuum leak in its prime science instrument, the Seismic Experiment for Interior Structure (SEIS).
- The new launch period for the mission begins May 5, 2018, with a Mars landing scheduled for Nov. 26, 2018. The next launch opportunity is driven by orbital dynamics, so 2018 is the soonest the lander can be on its way.
Launch: The InSight mission was launched on 5 May 2018 (11:05 UTC), on an Atlas V-401 vehicle of ULA from VAFB, CA. This is the 12th mission of NASA's Discovery Program, managed by the agency's Marshall Space Flight Center in Huntsville, Alabama. InSight is on a 483 million km trip to Mars to study for the first time what lies deep beneath the surface of the Red Planet. 20) 21)
• MarCO (Mars Cube One): The InSight flight will include two experimental 6U CubeSats (MarCO-A and MarCO-B) of NASA/JPL. This will be the first time CubeSats have flown in deep space. If this flyby demonstration is successful, the technology will provide NASA the ability to quickly transmit status information about the main spacecraft after it lands on Mars.
- The two CubeSats will separate from the Atlas V booster after launch and travel along their own trajectories to the Red Planet. After release from the launch vehicle, MarCO's first challenges are to deploy two radio antennas and two solar panels. The high-gain, X-band antenna is a flat panel engineered to direct radio waves the way a parabolic dish antenna does. MarCO will be navigated to Mars independently of the InSight spacecraft, with its own course adjustments on the way.
- NASA's two MarCO CubeSats will be flying past Mars in November 2018 just as NASA's next Mars lander, InSight, is descending through the Martian atmosphere and landing on the surface. MarCO will provide an experimental communications relay to inform Earth quickly about the landing.
- The MarCO mission is described in a separate file on the eoPortal.
Table 2: Aerojet Rocketdyne propulsion throughout the Insight mission 22)
The InSight cruise phase begins soon after separation from the launch vehicle when the spacecraft completes the launch phase. Cruise ends when the spacecraft is about 60 days from entry into the Martian atmosphere, beginning with approach. 23)
During cruise, the InSight lander is tucked inside its protective aeroshell, with the aeroshell attached to the cruise stage. The spacecraft makes several corrections to its trajectory by firing the cruise stage engines, with the first one just 10 days after launch. The purpose of these is to fine-tune the flight path so it hits just the right entry point at the top of the Martian atmosphere on landing day.
Orbit of InSight (Ref. 3):
• Very fast, type-1 trajectory: 6.5-month cruise to Mars
• Landing: November 26, 2018 on the landing site Elysium Planitia, Mars.
• Two-month deployment phase
• Two years (one Mars year) science operations on the surface; repetitive operations
• Nominal end-of-mission: November 24, 2020
Figure 12: Illustration of InSight trajectory to Mars (image credit: NASA/JPL)
Figure 13: Illustration of the InSight spacecraft with deployed solar panels during the cruise phase (image credit: NASA)
Some of the key activities during the cruise phase include:
- Health checks and maintenance of the spacecraft in its cruise configuration.
- Monitoring and calibration of the spacecraft and subsystems.
- Attitude correction turns (adjusts) to maintain the antenna pointing toward Earth for communications and to keep the solar panels pointed toward the Sun for power).
- Navigation activities, including trajectory correction maneuvers, to keep track of InSight’s position and precisely control it prior to approach.
- Preparation for entry, descent, and landing and surface operations, including communication tests used during entry, descent, and landing.
EDL (Entry, Descent, and Landing): EDL begins when the spacecraft reaches the Martian atmosphere, about 128 km above the surface, and ends with the lander safe and sound on the surface of Mars six minutes later. 24)
For InSight, this phase includes a combination of technologies inherited from past NASA Mars missions such as NASA’s Phoenix Mars Lander. This landing system weighs less than the airbags used for the twin rovers or the skycrane used by the Mars Science Laboratory. The lean landing hardware helps InSight place a higher ratio of science instruments to total launch mass on the surface of Mars.
Compared with Phoenix, though, InSight's landing presents four added challenges:
• InSight enters the atmosphere at higher velocity 6.3 km/s vs. 5.6 km/s.
• InSight has more mass entering the atmosphere — about 608 kg vs. 573 kg.
• InSight lands at an elevation of about 1.5 km higher than Phoenix did, so it has less atmosphere to use for deceleration.
• InSight lands during northern hemisphere autumn on Mars, when dust storms are known to have grown to global proportions in some prior years.
InSight will use a combination of parachutes and onboard engines to gently lower itself down to the Martian surface. The entire landing will last just seven minutes, and if it’s successful, the spacecraft will spend the next two years studying Mars and its interior.
Figure 14: Elysium Planitia, a flat-smooth plain just north of the equator makes for the perfect location from which to study the deep Martian interior (image credit: NASA) 25)
The InSight mission will place a stationary lander near Mars' equator (Figures 14 and 15). With two solar panels that unfold like paper fans, the lander spans about 6 meters. Within weeks after the landing — always a dramatic challenge on Mars — InSight will use a robotic arm to place its two main instruments directly and permanently onto the Martian ground, an unprecedented set of activities on Mars.
Figure 16: Mars Lander Deck of NASA's InSight Mission: This view looks upward toward the InSight Mars lander suspended upside down. It shows the top of the lander's science deck with the mission's two main science instruments SEIS and HP3 plus the robotic arm and other subsystems installed. The photo was taken on 9 Aug. 2017, in a Lockheed Martin clean room facility in Littleton, Colorado (image credit: NASA/JPL-Caltech, Lockheed Martin) 26)
Figure 17: NASA Mars InSight Overview (video credit: NASA/JPL)
• April 01, 2021: NASA’s InSight lander has detected two strong, clear quakes originating in a location of Mars called Cerberus Fossae – the same place where two strong quakes were seen earlier in the mission. The new quakes have magnitudes of 3.3 and 3.1; the previous quakes were magnitude 3.6 and 3.5. InSight has recorded over 500 quakes to date, but because of their clear signals, these are four of the best quake records for probing the interior of the planet. 27)
- Studying marsquakes is one way the InSight science team seeks to develop a better understanding of Mars’ mantle and core. The planet doesn’t have tectonic plates like Earth, but it does have volcanically active regions that can cause rumbles. The March 7 and March 18 quakes add weight to the idea that Cerberus Fossae is a center of seismic activity.
- “Over the course of the mission, we’ve seen two different types of marsquakes: one that is more ‘Moon-like’ and the other, more ‘Earth-like,’” said Taichi Kawamura of France’s Institut de Physique du Globe de Paris, which helped provide InSight’s seismometer and distributes its data along with the Swiss research university ETH Zürich. Earthquake waves travel more directly through the planet, while those of moonquakes tend to be very scattered; marsquakes fall somewhere in between. “Interestingly,” Kawamura continued, “all four of these larger quakes, which come from Cerberus Fossae, are ‘Earth-like.’”
- The new quakes have something else in common with InSight’s previous top seismic events, which occurred almost a full Martian year (two Earth years) ago: They occurred in the Martian northern summer. Scientists had predicted this would again be an ideal time to listen for quakes because winds would become calmer. The seismometer, called the Seismic Experiment for Interior Structure (SEIS), is sensitive enough that, even while it is covered by a dome-shaped shield to block it from wind and keep it from getting too cold, wind still causes enough vibration to obscure some marsquakes. During the past northern winter season, InSight couldn’t detect any quakes at all.
- “It’s wonderful to once again observe marsquakes after a long period of recording wind noise,” said John Clinton, a seismologist who leads InSight’s Marsquake Service at ETH Zürich. “One Martian year on, we are now much faster at characterizing seismic activity on the Red Planet.”
- The winds may have quieted down, but scientists are still hoping to improve their “listening” capability even more. Temperatures near the InSight lander may swing from almost minus 148 degrees Fahrenheit (minus 100 degrees Celsius) at night to 32 degrees Fahrenheit (0 degrees Celsius) during the day. These extreme temperature variations may be causing the cable connecting the seismometer to the lander to expand and contract, resulting in popping sounds and spikes in the data.
- So the mission team has begun trying to partially insulate the cable from the weather. They’ve started by using the scoop on the end of InSight’s robotic arm to drop soil on top of the domed Wind and Thermal Shield, allowing it to trickle down onto the cable. That allows the soil to get as close to the shield as possible without interfering with the shield’s seal with the ground. Burying the seismic tether is in fact one of the goals of the next phase of the mission, which NASA recently extended by two years, to December 2022.
- Despite the winds that have been shaking the seismometer, InSight’s solar panels remain covered with dust, and power is running lower as Mars moves away from the Sun. Energy levels are expected to improve after July, when the planet begins to approach the Sun again. Until then, the mission will successively turn off the lander’s instruments so that InSight can hibernate, waking periodically to check its health and communicate with Earth. The team hopes to keep the seismometer on for another month or two before it has to be temporarily turned off.
• February 12, 2021: As dust collects on the solar panels and winter comes to Elysium Planitia, the team is following a plan to reduce science operations in order to keep the lander safe. 28)
- NASA’s InSight lander recently received a mission extension for another two years, giving it time to detect more quakes, dust devils, and other phenomena on the surface of Mars. While the mission team plans to continue collecting data well into 2022, the increasing dustiness of the spacecraft’s solar panels and the onset of the Martian winter led to a decision to conserve power and temporarily limit the operation of its instruments.
- InSight was designed to be long-lasting: The stationary lander is equipped with solar panels, each spanning 7 feet (2 meters) across. InSight’s design was informed by that of the solar-powered Spirit and Opportunity rovers, with the expectation that the panels would gradually reduce their power output as dust settled on them but would have ample output to last through the two-year prime mission (completed in November 2020).
- Additionally, InSight’s team chose a landing site in Elysium Planitia, a windswept plain on the Red Planet’s equator that receives lots of sunlight. It was hoped that passing dust devils might clean off the panels, which happened many times with Spirit and Opportunity, allowing them to last years past their design lifetime.
- But despite InSight detecting hundreds of passing dust devils, none has been close enough to clean off those dinner-table-size panels since they unfurled on Mars in November 2018. Today, InSight’s solar arrays are producing just 27% of their dust-free capacity. That power has to be shared between science instruments, a robotic arm, the spacecraft’s radio, and a variety of heaters that keep everything in working order despite subfreezing temperatures. Since the windiest season of the Martian year has just ended, the team isn’t counting on a cleaning event in the coming months.
- Mars is currently moving toward what’s called aphelion, the point in its orbit when it’s farthest away from the Sun. That means the already-weak sunlight on the Martian surface is growing even fainter, reducing power when InSight most needs its heaters to stay warm. Mars will start approaching the Sun again in July 2021, after which the team will begin to resume full science operations.
- “The amount of power available over the next few months will really be driven by the weather,” said InSight’s project manager, Chuck Scott of NASA’s Jet Propulsion Laboratory in Southern California. “As part of our extended-mission planning, we developed an operations strategy to keep InSight safe through the winter so that we can resume science operations as solar intensity increases.” JPL leads the InSight mission, though the spacecraft and its solar panels were built by Lockheed Martin Space of Denver, Colorado.
- Over the coming weeks and months, InSight scientists will be carefully selecting which instruments need to be switched off each day to preserve power for heaters and energy-intensive activities like radio communication. InSight’s weather sensors are likely to remain off much of the time (resulting in infrequent updates to the mission’s weather page), and all the instruments will have to be powered off for some period around aphelion.
- Currently, power levels look strong enough to take the lander through the winter. But solar power generation on Mars is always a little uncertain. The Opportunity rover was forced to shut down after a series of dust storms darkened the Martian sky in 2019, and Spirit did not survive the Martian winter in 2010. If InSight were to run out of power due to a sudden dust storm, it is designed to be able to reboot itself when the sunlight returns if its electronics survived the extreme cold.
- Later this week, InSight will be commanded to extend its robotic arm over the panels so a camera can take close-up images of the dust coating. Then the team will pulse the motors that unfurled each panel after landing to try to can disturb the dust and see if the wind blows it away. The team considers this to be a long shot but worth the effort.
- “The InSight team has put together a strong plan to safely navigate through winter and emerge on the other side ready to complete our extended science mission through 2022,” said Bruce Banerdt of JPL, InSight’s principal investigator. “We’ve got a great vehicle and a top-notch team; I’m looking forward to many more new discoveries from InSight in the future.”
• January 14, 2021: The heat probe hasn’t been able to gain the friction it needs to dig, but the mission has been granted an extension to carry on with its other science. 29)
- The heat probe developed and built by the German Aerospace Center (DLR) and deployed on Mars by NASA’s InSight lander has ended its portion of the mission. Since Feb. 28, 2019, the probe, called the “mole,” has been attempting to burrow into the Martian surface to take the planet’s internal temperature, providing details about the interior heat engine that drives the Mars’ evolution and geology. But the soil’s unexpected tendency to clump deprived the spike-like mole of the friction it needs to hammer itself to a sufficient depth.
- After getting the top of the mole about 2 or 3 centimeters under the surface, the team tried one last time to use a scoop on InSight’s robotic arm to scrape soil onto the probe and tamp it down to provide added friction. After the probe conducted 500 additional hammer strokes on Saturday, Jan. 9, with no progress, the team called an end to their efforts.
- Part of an instrument called the Heat Flow and Physical Properties Package (HP3), the mole is a 16-inch-long (40-centimeter-long) pile driver connected to the lander by a tether with embedded temperature sensors. These sensors are designed to measure heat flowing from the planet once the mole has dug at least 10 feet (3 meters) deep.
- “We’ve given it everything we’ve got, but Mars and our heroic mole remain incompatible,” said HP3’s principal investigator, Tilman Spohn of DLR (Figure 18). “Fortunately, we’ve learned a lot that will benefit future missions that attempt to dig into the subsurface.”
- While NASA’s Phoenix lander scraped the top layer of the Martian surface, no mission before InSight has tried to burrow into the soil. Doing so is important for a variety of reasons: Future astronauts may need to dig through soil to access water ice, while scientists want to study the subsurface’s potential to support microbial life.
- “We are so proud of our team who worked hard to get InSight’s mole deeper into the planet. It was amazing to see them troubleshoot from millions of miles away,” said Thomas Zurbuchen, associate administrator for science at the agency’s headquarters in Washington. “This is why we take risks at NASA – we have to push the limits of technology to learn what works and what doesn’t. In that sense, we’ve been successful: We’ve learned a lot that will benefit future missions to Mars and elsewhere, and we thank our German partners from DLR for providing this instrument and for their collaboration.”
- The unexpected properties of the soil near the surface next to InSight will be puzzled over by scientists for years to come. The mole’s design was based on soil seen by previous Mars missions – soil that proved very different from what the mole encountered. For two years, the team worked to adapt the unique and innovative instrument to these new circumstances.
- “The mole is a device with no heritage. What we attempted to do – to dig so deep with a device so small – is unprecedented,” said Troy Hudson, a scientist and engineer at NASA’s Jet Propulsion Laboratory in Southern California who has led efforts to get the mole deeper into the Martian crust. “Having had the opportunity to take this all the way to the end is the greatest reward.”
- Besides learning about the soil at this location, engineers have gained invaluable experience operating the robotic arm. In fact, they used the arm and scoop in ways they never intended to at the outset of the mission, including pressing against and down on the mole. Planning the moves and getting them just right with the commands they were sending up to InSight pushed the team to grow.
- They’ll put their hard-earned wisdom to use in the future. The mission intends to employ the robotic arm in burying the tether that conveys data and power between the lander and InSight’s seismometer, which has recorded more than 480 marsquakes. Burying it will help reduce temperature changes that have created cracking and popping sounds in seismic data.
- There’s much more science to come from InSight, short for Interior Exploration using Seismic Investigations, Geodesy, and Heat Transport. NASA recently extended the mission for two more years, to Dec. 2022. Along with hunting for quakes, the lander hosts a radio experiment that is collecting data to reveal whether the planet’s core is liquid or solid. And InSight’s weather sensors are capable of providing some of the most detailed meteorological data ever collected on Mars. Together with weather instruments aboard NASA's Curiosity rover and its new Perseverance rover, which lands on Feb. 18, the three spacecraft will create the first meteorological network on another planet.
• October 16, 2020: NASA's InSight lander continues working to get its "mole" - a 16-inch-long (40 cm long) pile driver and heat probe - deep below the surface of Mars. A camera on InSight's arm recently took images of the now partially filled-in "mole hole," showing only the device's science tether protruding from the ground. 30)
Figure 18: NASA's InSight retracted its robotic arm on Oct. 3, 2020, revealing where the spike-like "mole" is trying to burrow into Mars. The copper-colored ribbon attached to the mole has sensors to measure the planet's heat flow. In the coming months, the arm will scrape and tamp down soil on top of the mole to help it dig (image credit: NASA/JPL-Caltech)
- Sensors embedded in the tether are designed to measure heat flowing from the planet once the mole has dug at least 10 feet (3 m) deep. The mission team has been working to help the mole burrow to at least that depth so that it can take Mars' temperature.
- The mole was designed so that loose soil would flow around it, providing friction against its outer hull so that it can dig deeper; without this friction, the mole just bounces in place as it hammers into the ground. But the soil where InSight landed is different than what previous missions have encountered: During hammering, the soil sticks together, forming a small pit around the device instead of collapsing around it and providing the necessary friction.
- After the mole unexpectedly backed out of the pit while hammering last year, the team placed the small scoop at the end of the lander's robotic arm on top of it to keep it in the ground. Now that the mole is fully embedded in the soil, they will use the scoop to scrape additional soil on top of it, tamping down this soil to help provide more friction. Because it will take months to pack down enough soil, the mole isn't expected to resume hammering until early 2021.
- "I'm very glad we were able to recover from the unexpected 'pop-out' event we experienced and get the mole deeper than it's ever been," said Troy Hudson, the scientist and engineer at NASA's Jet Propulsion Laboratory who led the work to get the mole digging. "But we're not quite done. We want to make sure there's enough soil on top of the mole to enable it to dig on its own without any assistance from the arm."
- The mole is formally called the Heat Flow and Physical Properties Package, or HP3, and was built and provided to NASA by the German Space Agency (DLR). JPL in Southern California leads the InSight mission. Read more about the mole's recent progress at this DLR blog.
• August 24, 2020: An electronics issue is suspected to be preventing the sensors from sharing their data about Mars weather with the spacecraft. 31)
- Weather sensors aboard NASA's InSight Mars lander stopped providing data on Sunday, Aug. 16, 2020, a result of an issue affecting the sensor suite's electronics. Engineers at NASA's Jet Propulsion Laboratory in Southern California are working to understand the cause of the issue.
- Called the Auxiliary Payload Sensor Suite (APSS), the sensors collect data on wind speed and direction, air temperature and pressure, and magnetic fields. Throughout each Martian day, or sol, InSight's main computer retrieves data stored in APSS' control computer for later transmission to orbiting spacecraft, which relay the data to Earth.
- APSS is in safe mode and unlikely to be reset before the end of the month while mission team members work toward a diagnosis. JPL engineers are optimistic that resetting the control computer may address the issue but need to investigate the situation further before returning the sensors to normal.
• August 5, 2020: Using data from NASA’s InSight Lander on Mars, Rice University seismologists of Houston, Texas, have made the first direct measurements of three subsurface boundaries from the crust to the core of the red planet. 32)
- “Ultimately it may help us understand planetary formation,” said Alan Levander, co-author of a study available online this week in Geophysical Research Letters. While the thickness of Mars’ crust and the depth of its core have been calculated with a number of models, Levander said the InSight data allowed for the first direct measurements, which can be used to check models and ultimately to improve them. 33)
Figure 19: An artist’s impression of Mars’ inner structure. The topmost layer is the crust, and beneath it is the mantle, which rests on a solid inner core (image courtesy of NASA/JPL-Caltech)
- “In the absence of plate tectonics on Mars, its early history is mostly preserved compared with Earth,” said study co-author Sizhuang Deng, a Rice graduate student. “The depth estimates of Martian seismic boundaries can provide indications to better understand its past as well as the formation and evolution of terrestrial planets in general.”
- Finding clues about Mars’ interior and the processes that formed it are key goals for InSight, a robotic lander that touched down in November 2018. The probe’s dome-shaped seismometer allows scientists to listen to faint rumblings inside the planet, in much the way that a doctor might listen to a patient’s heartbeat with a stethoscope.
- Seismometers measure vibrations from seismic waves. Like circular ripples that mark the spot where a pebble disturbed the surface of a pond, seismic waves flow through planets, marking the location and size of disturbances like meteor strikes or earthquakes, which are aptly called marsquakes on the red planet. InSight’s seismometer recorded more than 170 of these from February to September 2019.
- Seismic waves are also subtly altered as they pass through different kinds of rock. Seismologists have studied the patterns in seismographic recordings on Earth for more than a century and can use them to map the location of oil and gas deposits and much deeper strata.
- “The traditional way to investigate structures beneath Earth is to analyze earthquake signals using dense networks of seismic stations,” said Deng. “Mars is much less tectonically active, which means it will have far fewer marsquake events compared with Earth. Moreover, with only one seismic station on Mars, we cannot employ methods that rely on seismic networks.”
- Levander, Rice’s Carey Croneis Professor of Earth, Environmental and Planetary Sciences, and Deng analyzed InSight’s 2019 seismology data using a technique called ambient noise autocorrelation. “It uses continuous noise data recorded by the single seismic station on Mars to extract pronounced reflection signals from seismic boundaries,” Deng said.
- The first boundary Deng and Levander measured is the divide between Mars’ crust and mantle almost 35 kilometers beneath the lander.
- The second is a transition zone within the mantle where magnesium iron silicates undergo a geochemical change. Above the zone, the elements form a mineral called olivine, and beneath it, heat and pressure compress them into a new mineral called wadsleyite. Known as the olivine-wadsleyite transition, this zone was found 1,110 - 1,170 km beneath InSight.
- “The temperature at the olivine-wadsleyite transition is an important key to building thermal models of Mars,” Deng said. “From the depth of the transition, we can easily calculate the pressure, and with that, we can derive the temperature.”
- The third boundary he and Levander measured is the border between Mars’ mantle and its iron-rich core, which they found about 1,520 - 1,600 km beneath the lander. Better understanding this boundary “can provide information about the planet’s development from both a chemical and thermal point of view,” Deng said.
- The research was supported by Rice’s Department of Earth, Environmental and Planetary Sciences.
• July 7, 2020: NASA's InSight lander has been using its robotic arm to help the heat probe known as the "mole" burrow into Mars. The mission is providing the first look at the Red Planet's deep interior to reveal details about the formation of Mars and, ultimately, all rocky planets, including Earth. 34)
Figure 20: The movement of sand grains in the scoop on the end of NASA InSight's robotic arm suggests that the spacecraft's self-hammering "mole," which is in the soil beneath the scoop, had begun tapping the bottom of the scoop while hammering on June 20, 2020 (image credit: NASA/JPL-Caltech)
- Akin to a 16-inch-long (40-centimeter-long) pile driver, the self-hammering mole has experienced difficulty getting into the Martian soil since February 2019. It's mostly buried now, thanks to recent efforts to push down on the mole with the scoop on the end of the robotic arm. But whether it will be able to dig deep enough - at least 10 feet (3 meters) - to get an accurate temperature reading of the planet remains to be seen. Images taken by InSight during a Saturday, June 20, hammering session show bits of soil jostling within the scoop - possible evidence that the mole had begun bouncing in place, knocking the bottom of the scoop.
- While the campaign to save the mole continues, the arm will be used to help carry out other science and engineering work. Here's what you can expect in the months ahead from the mission, which is led by NASA's Jet Propulsion Laboratory in Southern California.
What's next for the mole?
- The mole is part of an instrument called the Heat Flow and Physical Properties Package, or HP3, that the German Aerospace Center (DLR) provided NASA. While the scoop on the end of InSight's arm has blocked the mole from backing out of its pit again, it also blocks the arm's camera from seeing the mole and the pit that has formed around it. Over the next few weeks, the team will move the arm out of the way to better assess how the soil and mole are interacting.
- The mole needs friction from soil in order to burrow. Ironically, loose soil provides that friction as it collapses around the mole. But the soil beneath InSight has proven to be cement-like duricrust, with dirt granules that stick together. As a result, recoil from the mole's self-hammering action causes it to bounce in place. So the team's next moves may be to provide that friction by scraping or chopping nearby soil to move it into the pit it's in.
- More thoughts about the mole's recent progress can be found on a blog written by HP3's principal investigator, Tilman Spohn of DLR.
What's next for InSight's arm?
- InSight landed on Mars on Nov. 26, 2018. Its robotic arm subsequently set HP3, a seismometer and the seismometer's Wind and Thermal Shield on to the planet's surface. While the arm has been key to helping the mole, scientists and engineers are eager to use the arm's camera to pan over InSight's solar panels, something they haven't done since July 17, 2019.
- It's the dusty season on Mars, and the panels are likely coated with a fine layer of reddish-brown particles. Estimating how much dust is on the solar panels will let engineers better understand InSight's daily power supply.
- Scientists also want to resume using the arm to spot meteors streaking across the night sky, as they did earlier in the mission. Doing so could help them predict how often meteors strike this part of the planet. They could also cross-check to see whether data from InSight's seismometer reveals a meteor impact on Mars shortly afterward.
What's next for the seismometer?
- InSight's seismometer, called the Seismic Experiment for Interior Structure (SEIS), detected its first marsquake nearly three months after starting its measurements in January 2019. By the fall of 2019, it was detecting a potential quake or two per day. While SEIS has detected more than 480 seismic signals overall, the rate has dropped to less than one per week.
- This rate change is tied to seasonal variations of atmospheric turbulence, which creates noise that covers up the tiny quake signals. Despite the protective Wind and Thermal Shield, SEIS is sensitive enough that shaking from the wind hitting the shield can make quakes harder to isolate.
More About InSight
- JPL manages InSight for NASA's Science Mission Directorate. InSight is part of NASA's Discovery Program, managed by the agency's Marshall Space Flight Center in Huntsville, Alabama. Lockheed Martin Space in Denver built the InSight spacecraft, including its cruise stage and lander, and supports spacecraft operations for the mission.
- A number of European partners, including France's Centre National d'Études Spatiales (CNES) and the German Aerospace Center (DLR), are supporting the InSight mission. CNES provided the Seismic Experiment for Interior Structure (SEIS) instrument to NASA, with the principal investigator at IPGP (Institut de Physique du Globe de Paris). Significant contributions for SEIS came from IPGP; the Max Planck Institute for Solar System Research (MPS) in Germany; the Swiss Federal Institute of Technology (ETH Zurich) in Switzerland; Imperial College London and Oxford University in the United Kingdom; and JPL. DLR provided the Heat Flow and Physical Properties Package (HP3) instrument, with significant contributions from the Space Research Center (CBK) of the Polish Academy of Sciences and Astronika in Poland. Spain's Centro de Astrobiología (CAB) supplied the temperature and wind sensors.
• February 24, 2020: A new understanding of Mars is beginning to emerge, thanks to the first year of NASA's InSight lander mission. Findings described in a set of six papers published today reveal a planet alive with quakes, dust devils and strange magnetic pulses. 35)
- Five of the papers were published in Nature. An additional paper in Nature Geoscience details the InSight spacecraft's landing site, a shallow crater nicknamed "Homestead hollow" in a region called Elysium Planitia.
- InSight is the first mission dedicated to looking deep beneath the Martian surface. Among its science tools are a seismometer for detecting quakes, sensors for gauging wind and air pressure, a magnetometer, and a heat flow probe designed to take the planet's temperature.
Figure 21: A cutaway view of Mars showing the InSight lander studying seismic activity ( image credit: J. T. Keane/Nature Geoscience)
- While the team continues to work on getting the probe into the Martian surface as intended, the ultra-sensitive seismometer, called the Seismic Experiment for Interior Structure (SEIS), has enabled scientists to "hear" multiple trembling events from hundreds to thousands of miles away.
- Seismic waves are affected by the materials they move through, giving scientists a way to study the composition of the planet's inner structure. Mars can help the team better understand how all rocky planets, including Earth, first formed.
- Mars trembles more often - but also more mildly - than expected. SEIS has found more than 450 seismic signals to date, the vast majority of which are probably quakes (as opposed to data noise created by environmental factors, like wind). The largest quake was about magnitude 4.0 in size - not quite large enough to travel down below the crust into the planet's lower mantle and core. Those are "the juiciest parts of the apple" when it comes to studying the planet's inner structure, said Bruce Banerdt, InSight principal investigator at JPL.
- Scientists are ready for more: It took months after InSight's landing in November 2018 before they recorded the first seismic event. By the end of 2019, SEIS was detecting about two seismic signals a day, suggesting that InSight just happened to touch down at a particularly quiet time. Scientists still have their fingers crossed for "the Big One."
- Mars doesn't have tectonic plates like Earth, but it does have volcanically active regions that can cause rumbles. A pair of quakes was strongly linked to one such region, Cerberus Fossae, where scientists see boulders that may have been shaken down cliffsides. Ancient floods there carved channels nearly 800 miles (1,300 km) long. Lava flows then seeped into those channels within the past 10 million years - the blink of an eye in geologic time.
- Some of these young lava flows show signs of having been fractured by quakes less than 2 million years ago. "It's just about the youngest tectonic feature on the planet," said planetary geologist Matt Golombek of JPL. "The fact that we're seeing evidence of shaking in this region isn't a surprise, but it's very cool."
At the Surface
- Billions of years ago, Mars had a magnetic field. It is no longer present, but it left ghosts behind, magnetizing ancient rocks that are now between 200 feet (61 meters) to several miles below ground. InSight is equipped with a magnetometer - the first on the surface of Mars to detect magnetic signals.
- The magnetometer has found that the signals at Homestead hollow are 10 times stronger than what was predicted based on data from orbiting spacecraft that study the area. The measurements of these orbiters are averaged over a couple of hundred miles, whereas InSight's measurements are more local.
- Because most surface rocks at InSight's location are too young to have been magnetized by the planet's former field, "this magnetism must be coming from ancient rocks underground," said Catherine Johnson, a planetary scientist at the University of British Columbia and the Planetary Science Institute. "We're combining these data with what we know from seismology and geology to understand the magnetized layers below InSight. How strong or deep would they have to be for us to detect this field?"
- In addition, scientists are intrigued by how these signals change over time. The measurements vary by day and night; they also tend to pulse around midnight. Theories are still being formed as to what causes such changes, but one possibility is that they're related to the solar wind interacting with the Martian atmosphere.
In the Wind
- InSight measures wind speed, direction and air pressure nearly continuously, offering more data than previous landed missions. The spacecraft's weather sensors have detected thousands of passing whirlwinds, which are called dust devils when they pick up grit and become visible. "This site has more whirlwinds than any other place we've landed on Mars while carrying weather sensors," said Aymeric Spiga, an atmospheric scientist at Sorbonne University in Paris.
- Despite all that activity and frequent imaging, InSight's cameras have yet to see dust devils. But SEIS can feel these whirlwinds pulling on the surface like a giant vacuum cleaner. "Whirlwinds are perfect for subsurface seismic exploration," said Philippe Lognonné of Institut de Physique du Globe de Paris (IPGP), principal investigator of SEIS.
Still to come: The Core
- InSight has two radios: one for regularly sending and receiving data, and a more powerful radio designed to measure the "wobble" of Mars as it spins. This X-band radio, also known as the Rotation and Interior Structure Experiment (RISE), can eventually reveal whether the planet's core is solid or liquid. A solid core would cause Mars to wobble less than a liquid one would.
- This first year of data is just a start. Watching over a full Martian year (two Earth years) will give scientists a much better idea of the size and speed of the planet's wobble.
• October 17, 2019: NASA's InSight spacecraft has used its robotic arm to help its heat probe, known as "the mole," dig nearly 2 cm over the past week. While modest, the movement is significant: Designed to dig as much as 5 meters underground to gauge the heat escaping from the planet's interior, the mole has only managed to partially bury itself since it started hammering in February 2019. 36)
- The recent movement is the result of a new strategy, arrived at after extensive testing on Earth, which found that unexpectedly strong soil is holding up the mole's progress. The mole needs friction from surrounding soil in order to move: Without it, recoil from its self-hammering action will cause it to simply bounce in place. Pressing the scoop on InSight's robotic arm against the mole, a new technique called "pinning," appears to provide the probe with the friction it needs to continue digging.
- Since Oct. 8, 2019, the mole has hammered 220 times over three separate occasions. Images sent down from the spacecraft's cameras have shown the mole gradually progressing into the ground. It will take more time - and hammering - for the team to see how far the mole can go.
- The mole is part of an instrument called the HP3 (Heat Flow and Physical Properties Package), which was provided by the German Aerospace Center (DLR).
- "Seeing the mole's progress seems to indicate that there's no rock blocking our path," said HP3 Principal Investigator Tilman Spohn of DLR. "That's great news! We're rooting for our mole to keep going."
• October 3, 2019: NASA's InSight lander, which is on a mission to explore the deep interior of Mars, positioned its robotic arm this past weekend to assist the spacecraft's self-hammering heat probe. Known as "the mole," the probe has been unable to dig more than about 35 cm since it began burying itself into the ground on Feb. 28, 2019. 37)
- The maneuver is in preparation for a tactic, to be tried over several weeks, called "pinning."
Figure 22: NASA InSight's robotic arm will use its scoop to pin the spacecraft's heat probe, or "mole," against the wall of its hole. The mole is part of an instrument formally called the HP3 (Heat Flow and Physical Properties Package), provided by DLR (image credit: NASA/JPL-Caltech)
- "We're going to try pressing the side of the scoop against the mole, pinning it to the wall of its hole," said InSight Deputy Principal Investigator Sue Smrekar of NASA's Jet Propulsion Laboratory in Pasadena, California. "This might increase friction enough to keep it moving forward when mole hammering resumes."
Figure 23: NASA’s InSight lander on Mars is trying to use its robotic arm to get the mission’s heat flow probe, or mole, digging again. InSight team engineer Ashitey Trebbi-Ollennu, based at NASA’s Jet Propulsion Laboratory in Pasadena, California, explains what has been attempted and the game plan for the coming weeks. The next tactic they'll try will be "pinning" the mole against the hole it's in (video credit: NASA/JPL)
- Whether the extra pressure on the mole will compensate for the unique soil remains an unknown.
- Designed to burrow as much as 5 meters underground to record the amount of heat escaping from the planet's interior, the mole needs friction from surrounding soil in order to dig: Without it, recoil from the self-hammering action causes it to simply bounce in place, which is what the mission team suspects is happening now.
- While JPL manages the InSight mission for NASA, the German Aerospace Center (DLR) provided the heat probe, which is part of an instrument called the Heat Flow and Physical Properties Package (HP3). Back in June, the team devised a plan to help the heat probe. The mole wasn't designed to be picked up and relocated once it begins digging. Instead, the robotic arm removed a support structure intended to hold the mole steady as it digs into the Martian surface.
- Removing the structure allowed the InSight team to get a better look at the hole that formed around the mole as it hammered. It's possible that the mole has hit a rock, but testing by DLR suggested the issue was soil that clumps together rather than falling around the mole as it hammers. Sure enough, the arm's camera discovered that below the surface appears to be 5 to 10 cm of duricrust, a kind of cemented soil thicker than anything encountered on other Mars missions and different from the soil the mole was designed for.
- "All we know about the soil is what we can see in images InSight sends us," said Tilman Spohn, HP3's principal investigator at DLR. "Since we can't bring the soil to the mole, maybe we can bring the mole to the soil by pinning it in the hole."
- Using a scoop on the robotic arm, the team poked and pushed the soil seven times over the summer in an effort to collapse the hole. No such luck. It shouldn't take much force to collapse the hole, but the arm isn't pushing at full strength. The team placed HP3 as far from the lander as possible so that the spacecraft's shadow wouldn't influence the heat probe's temperature readings. As a result, the arm, which wasn't intended to be used this way, has to stretch out and press at an angle, exerting much less force than if the mole were closer.
- "We're asking the arm to punch above its weight," said Ashitey Trebi-Ollennu, the lead arm engineer at JPL. "The arm can't push the soil the way a person can. This would be easier if it could, but that's just not the arm we have."
- Interplanetary rescue operations aren't new to NASA. The Mars Exploration Rover team helped save Spirit and Opportunity on more than one occasion. Coming up with workable solutions requires an extraordinary amount of patience and planning. JPL has a working replica of InSight to practice arm movements, and it has a working model of the heat probe as well.
- Besides pinning, the team is also testing a technique to use the scoop in the way it was originally intended to work: scraping soil into the hole rather than trying to compress it. Both techniques might be visible to the public in raw images that come down from InSight in the near future.
• October 1, 2019: Put an ear to the ground on Mars and you'll be rewarded with a symphony of sounds. Granted, you'll need superhuman hearing, but NASA's InSight lander comes equipped with a very special "ear." 38)
Figure 24: NASA's InSight used its Instrument Context Camera (ICC) beneath the lander's deck to image these drifting clouds at sunset. This series of images was taken on April 25, 2019, the 145th Martian day, or sol, of the mission, starting at around 6:30 p.m. Mars local time (image credit: NASA/JPL-Caltech)
- The spacecraft's exquisitely sensitive seismometer, called the Seismic Experiment for Interior Structure (SEIS), can pick up vibrations as subtle as a breeze. The instrument was provided by the French space agency, Centre National d'Études Spatiales (CNES), and its partners.
- SEIS was designed to listen for marsquakes. Scientists want to study how the seismic waves of these quakes move through the planet's interior, revealing the deep inner structure of Mars for the first time.
- But after the seismometer was set down by InSight's robotic arm, Mars seemed shy. It didn't produce its first rumbling until this past April, and this first quake turned out to be an odd duck. It had a surprisingly high-frequency seismic signal compared to what the science team has heard since then. Out of more than 100 events detected to date, about 21 are strongly considered to be quakes. The remainder could be quakes as well, but the science team hasn't ruled out other causes.
- Put on headphones to listen to two of the more representative quakes SEIS has detected. These occurred on May 22, 2019 (the 173rd Martian day, or sol, of the mission) and July 25, 2019 (Sol 235). Far below the human range of hearing, these sonifications from SEIS had to be speeded up and slightly processed to be audible through headphones. Both were recorded by the "very broad band sensors" on SEIS, which are more sensitive at lower frequencies than its short period sensors.
- The Sol 173 quake is about a magnitude 3.7; the Sol 235 quake is about a magnitude 3.3.
Figure 25: A recording of a magnitude 3.7 marsquake from InSight's seismometer, called SEIS. This quake was recorded on May 22, 2019 (the 173rd Martian day, or sol, of the mission). Far below the human range of hearing, this sonification from SEIS had to be sped up and slightly processed to be audible through headphones (image credit: NASA/JPL-Caltech)
Figure 26: A recording of a magnitude 3.3 marsquake from InSight's seismometer, called SEIS. This quake was recorded on July 25, 2019 (Sol 235). Far below the human range of hearing, this sonification from SEIS had to be sped up and slightly processed to be audible through headphones (image credit: NASA/JPL-Caltech)
- Each quake is a subtle rumble. The Sol 235 quake becomes particularly bass-heavy toward the end of the event. Both suggest that the Martian crust is like a mix of the Earth's crust and the Moon's. Cracks in Earth's crust seal over time as water fills them with new minerals. This enables sound waves to continue uninterrupted as they pass through old fractures. Drier crusts like the Moon's remain fractured after impacts, scattering sound waves for tens of minutes rather than allowing them to travel in a straight line. Mars, with its cratered surface, is slightly more Moon-like, with seismic waves ringing for a minute or so, whereas quakes on Earth can come and go in seconds.
Mechanical Sounds and Wind Gusts
- SEIS has no trouble identifying quiet quakes, but its sensitive ear means scientists have lots of other noises to filter out. Over time, the team has learned to recognize the different sounds. And while some are trickier than others to spot, they all have made InSight's presence on Mars feel more real to those working with the spacecraft.
- "It's been exciting, especially in the beginning, hearing the first vibrations from the lander," said Constantinos Charalambous, an InSight science team member at Imperial College London who works with the SP sensors. "You're imagining what's really happening on Mars as InSight sits on the open landscape."
- Charalambous and Nobuaki Fuji of Institut de Physique du Globe de Parisprovided the audio samples for this story, including the one below, which is also best heard with headphones and captures the array of sounds they're hearing.
Figure 27: Listen to NASA's InSight at Work on Mars. NASA's InSight lander placed a seismometer on the Martian surface to study marsquakes. While it's found many, it has also detected other kinds of seismic signals, including some produced by the spacecraft itself. That includes wind gusts, InSight's robotic arm moving around and "dinks and donks," friction caused by parts inside the seismometer moving against each other as the temperature changes (video credit: NASA/JPL)
• August 23, 2019: The daily chatter between antennas here on Earth and those on NASA spacecraft at Mars is about to get much quieter for a few weeks. 39)
Figure 28: This animation illustrates Mars solar conjunction, a period when Mars is on the opposite side of the Sun from Earth. During this time, the Sun can interrupt radio transmissions to spacecraft on and around the Red Planet (image credit: NASA/JPL-Caltech)
- That's because Mars and Earth will be on opposite sides of the Sun, a period known as Mars solar conjunction. The Sun expels hot, ionized gas from its corona, which extends far into space. During solar conjunction, this gas can interfere with radio signals when engineers try to communicate with spacecraft at Mars, corrupting commands and resulting in unexpected behavior from our deep space explorers.
- To be safe, engineers hold off on sending commands when Mars disappears far enough behind the Sun's corona that there's increased risk of radio interference.
- "It's that time again," said Roy Gladden, manager of the Mars Relay Network at NASA's Jet Propulsion Laboratory in Pasadena, California. "Our engineers have been preparing our spacecraft for conjunction for months. They'll still be collecting science data at Mars, and some will attempt to send that data home. But we won't be commanding the spacecraft out of concern that they could act on a corrupted command."
When is this taking place?
- Solar conjunction occurs every two years. This time, the hold on issuing commands - called a "command moratorium" - will run from Aug. 28 to Sept. 7, 2019. Some missions will have stopped commanding their spacecraft earlier in preparation for the moratorium.
What happens to the spacecraft?
- Although some instruments aboard spacecraft - especially cameras that generate large amounts of data - will be inactive, all of NASA's Mars spacecraft will continue their science; they'll just have much simpler "to-do" lists than they normally would carry out.
- On the surface of Mars, the Curiosity rover will stop driving, while the InSight lander won't move its robotic arm. Above Mars, both the Odyssey orbiter and the Mars Reconnaissance Orbiter will continue collecting data from Curiosity and InSight for return to Earth. However, only Odyssey will attempt to relay that data to Earth before conjunction ends. Meantime, another orbiter, MAVEN, will continue to collect its own science data but won't support any relay operations during this time.
- All of this means that there will be a temporary pause in the stream of raw images available from Curiosity, InSight and the other Mars missions. Mars solar conjunction impacts operations of all spacecraft currently at Mars, not just NASA's.
What happens when solar conjunction ends?
- Once conjunction is over, the spacecraft will beam the data they've collected to NASA's Deep Space Network, a system of massive Earth-based radio antennas managed by JPL. Engineers will spend about a week downloading the information before normal spacecraft operations resume.
- If the teams monitoring these missions determine any of the collected science data are corrupted, they can usually have that data retransmitted after the moratorium ends on Sept. 7.
• July 22, 2019: Southern California got all shook up after a set of recent quakes. But Earth isn't the only place that experiences quakes: Both the Moon and Mars have them as well. NASA sent the first seismometer to the Moon 50 years ago, during the Apollo 11 mission; the agency's InSight lander brought the first seismometer to Mars in late 2018, and it's called the Seismic Experiment for Interior Structure (SEIS). 40)
- Provided by the French space agency, Centre National d'Études Spatiales (CNES), the seismometer detected its first marsquake on April 6, 2019. The InSight mission's Marsquake Service, which monitors the data from SEIS, is led by Swiss research university ETH Zurich.
Figure 29: This artist's concept is a simulation of what seismic waves from a marsquake might look like as they move through different layers of the Martian interior (image credit: NASA/JPL-Caltech/ETH Zurich/ Van Driel)
- Quakes look and feel different depending on the material their seismic waves pass through. In a new video, scientists at ETH demonstrate this by using data from the Apollo-era seismometers on the Moon, two of the first quakes detected on Mars by SEIS and quakes recorded here on Earth.
- By running data from these worlds through a quake simulator, or "shake room," scientists can experience for themselves how different the earthquakes can be. Researchers had to amplify the marsquake signals by a factor of 10 million in order to make the quiet and distant tremors perceptible in comparison to the similarly amplified moonquakes and unamplified earthquakes.
Figure 30: Fifty years after Apollo 11 astronauts deployed the first seismometer on the surface of the Moon, NASA InSight's seismic experiment transmits data giving researchers the opportunity to compare marsquakes to moon and earthquakes. The Marsquake Service (MQS) center at ETH Zurich in Switzerland monitors daily seismic activity on Mars (video credit: ETH Zürich, Published on Jul 19, 2019)
• July 1, 2019: Behold the "mole": The heat-sensing spike that NASA's InSight lander deployed on the Martian surface is now visible. Last week, the spacecraft's robotic arm successfully removed the support structure of the mole, which has been unable to dig, and placed it to the side. Getting the structure out of the way gives the mission team a view of the mole - and maybe a way to help it dig. 41)
Figure 31: On 28 June 2019, NASA's InSight lander used its robotic arm to move the support structure for its digging instrument, informally called the "mole." This view was captured by the fisheye Instrument Context Camera under the lander's deck (image credit: NASA/JPL- Caltech)
Figure 32: Lifting the support structure had been done in three steps, a bit at a time, to ensure the mole wasn't pulled out of the surface. Moving the structure out of the way will give the InSight team a better look at the mole and allow them to try to help it dig (image credit: NASA/JPL- Caltech)
- "We've completed the first step in our plan to save the mole," said Troy Hudson of a scientist and engineer with the InSight mission at NASA's Jet Propulsion Laboratory in Pasadena, California. "We're not done yet. But for the moment, the entire team is elated because we're that much closer to getting the mole moving again."
- Part of an instrument called the Heat Flow and Physical Properties Package (HP3), the self-hammering mole is designed to dig down as much as 16 feet (5 m) and take Mars' temperature. But the mole hasn't been able to dig deeper than about 12 inches (30 cm), so on Feb. 28, 2019 the team commanded the instrument to stop hammering so that they could determine a path forward.
- Scientists and engineers have been conducting tests to save the mole at JPL, which leads the InSight mission, as well as at the German Aerospace Center (DLR), which provided HP3. Based on DLR testing, the soil may not provide the kind of friction the mole was designed for. Without friction to balance the recoil from the self-hammering motion, the mole would simply bounce in place rather than dig.
- One sign of this unexpected soil type is apparent in images taken by a camera on the robotic arm: A small pit has formed around the mole as it's been hammering in place.
- "The images coming back from Mars confirm what we've seen in our testing here on Earth," said HP3 Project Scientist Mattias Grott of DLR. "Our calculations were correct: This cohesive soil is compacting into walls as the mole hammers."
- The team wants to press on the soil near this pit using a small scoop on the end of the robotic arm. The hope is that this might collapse the pit and provide the necessary friction for the mole to dig.
- It's also still possible that the mole has hit a rock. While the mole is designed to push small rocks out of the way or deflect around them, larger ones will prevent the spike's forward progress. That's why the mission carefully selected a landing site that would likely have both fewer rocks in general and smaller ones near the surface.
- The robotic arm's grapple isn't designed to lift the mole once it's out of its support structure, so it won't be able to relocate the mole if a rock is blocking it.
- The team will be discussing what next steps to take based on careful analysis. Later this month, after releasing the arm's grapple from the support structure, they'll bring a camera in for some detailed images of the mole.
• June 5, 2019: Engineers in a Mars-like test area at NASA's Jet Propulsion Laboratory try possible strategies to aid the Heat Flow and Physical Properties Package (HP3) on NASA's InSight lander, using engineering models of the lander, robotic arm and instrument. 42)
Figure 33: In this image, the model's robotic arm is lifting up part of HP3 to expose the self-hammering mole that is partially embedded in the testbed soil. Standing mid-ground are engineers Ashitey Trebi-Ollennu (left) and Troy Lee Hudson (right). Lights in the testbed intended to simulate Mars' lighting conditions give the image an orange tint. Engineers at the German Aerospace Center (DLR), which provided HP3, have also been working on strategies to help the probe (image credit: NASA/JPL, Caltech)
• April 23, 2019: NASA’s Mars InSight lander has measured and recorded for the first time ever a likely “marsquake.” The faint seismic signal, detected by the lander’s Seismic Experiment for Interior Structure (SEIS) instrument, was recorded on April 6, the lander’s 128th Martian day, or sol. This is the first recorded trembling that appears to have come from inside the planet, as opposed to being caused by forces above the surface, such as wind. Scientists still are examining the data to determine the exact cause of the signal. 43)
Figure 34: This video and audio illustrates a seismic event detected by NASA's Mars InSight rover on April 6, 2019, the 128th Martian day, or sol, of the mission. Three distinct kinds of sounds can be heard, all of them detected as ground vibrations by the spacecraft's seismometer, called the Seismic Experiment for Interior Structure (SEIS): noise from Martian wind, the seismic event itself, and the spacecraft's robotic arm as it moves to take pictures (video credit: NASA/JPL-Caltech/CNES/IPGP/Imperial College London)
- “InSight’s first readings carry on the science that began with NASA’s Apollo missions,” said InSight Principal Investigator Bruce Banerdt of NASA’s Jet Propulsion Laboratory (JPL) in Pasadena, California. “We’ve been collecting background noise up until now, but this first event officially kicks off a new field: Martian seismology!”
- The new seismic event was too small to provide solid data on the Martian interior, which is one of InSight’s main objectives. The Martian surface is extremely quiet, allowing SEIS, InSight’s specially designed seismometer, to pick up faint rumbles. In contrast, Earth’s surface is quivering constantly from seismic noise created by oceans and weather. An event of this size in Southern California would be lost among dozens of tiny crackles that occur every day.
- “The Martian Sol 128 event is exciting because its size and longer duration fit the profile of moonquakes detected on the lunar surface during the Apollo missions,” said Lori Glaze, Planetary Science Division director at NASA Headquarters.
- NASA’s Apollo astronauts installed five seismometers that measured thousands of quakes while operating on the Moon between 1969 and 1977, revealing seismic activity on the Moon. Different materials can change the speed of seismic waves or reflect them, allowing scientists to use these waves to learn about the interior of the Moon and model its formation. NASA currently is planning to return astronauts to the Moon by 2024, laying the foundation that will eventually enable human exploration of Mars.
- InSight’s seismometer, which the lander placed on the planet’s surface on Dec. 19, 2018, will enable scientists to gather similar data about Mars. By studying the deep interior of Mars, they hope to learn how other rocky worlds, including Earth and the Moon, formed.
- Three other seismic signals occurred on March 14 (Sol 105), April 10 (Sol 132) and April 11 (Sol 133). Detected by SEIS’ more sensitive Very Broad Band sensors, these signals were even smaller than the Sol 128 event and more ambiguous in origin. The team will continue to study these events to try to determine their cause.
- Regardless of its cause, the Sol 128 signal is an exciting milestone for the team.
- “We’ve been waiting months for a signal like this,” said Philippe Lognonné, SEIS team lead at the Institut de Physique du Globe de Paris (IPGP) in France. “It's so exciting to finally have proof that Mars is still seismically active. We're looking forward to sharing detailed results once we've had a chance to analyze them.”
- Most people are familiar with quakes on Earth, which occur on faults created by the motion of tectonic plates. Mars and the Moon do not have tectonic plates, but they still experience quakes – in their cases, caused by a continual process of cooling and contraction that creates stress. This stress builds over time, until it is strong enough to break the crust, causing a quake.
- Detecting these tiny quakes required a huge feat of engineering. On Earth, high-quality seismometers often are sealed in underground vaults to isolate them from changes in temperature and weather. InSight’s instrument has several ingenious insulating barriers, including a cover built by JPL called the Wind and Thermal Shield, to protect it from the planet's extreme temperature changes and high winds.
- SEIS has surpassed the team’s expectations in terms of its sensitivity. The instrument was provided for InSight by the French space agency, Centre National d’Études Spatiales (CNES), while these first seismic events were identified by InSight's Marsquake Service team, led by the Swiss Federal Institute of Technology.
- “We are delighted about this first achievement and are eager to make many similar measurements with SEIS in the years to come,” said Charles Yana, SEIS mission operations manager at CNES.
• April 11, 2019: InSight's Heat and Physical Properties Package (HP3) instrument completed a new round of diagnostic hammering into the Martian surface on March 26, 2019, while the spacecraft's seismometer listened in. The team working with the heat probe is continuing to analyze seismic data from this test. Based on the time between hammer strikes, scientists may be able to learn something new about what's obstructing the probe from digging farther underground. 44)
- This week, the German Aerospace Center (DLR) is busy wrapping up tests at a facility in Bremen, Germany, to better understand the properties of Martian soil. There are many questions about how the soil around InSight compacts or shifts during hammering. In addition to investigating whether the probe has struck a rock or a layer of gravel, scientists are exploring whether this sand isn't providing enough friction for the probe, also known as "the mole," to dig down.
• April 11, 2019: DLR is simulating the current situation on Mars. After its first hammering operation on 28 February 2019, the DLR HP3 (Heat and Physical Properties Package), the Mars Mole, was only able to drive itself about 30 cm into the Martian subsurface. DLR planetary researchers and engineers are now analyzing how this could have happened and looking into what measures could be taken to remedy the situation. "We are investigating and testing various possible scenarios to find out what led to the 'Mole' stopping," explains Torben Wippermann, Test Leader at the DLR Institute of Space Systems in Bremen. The basis for the scientists' work: some images, temperature data, data from the radiometer and recordings made by the French SEIS (Seismic Experiment for Interior Structure) during a brief hammering test conducted on 26 March 2019. 45)
- When the NASA InSight lander arrived on the Martian surface, everything looked even better than expected. Although the lander's camera showed numerous rocks some distance away, the immediate surroundings were free of rocks and debris. The reason why the 'Mole' hammered its way quickly into the ground after being placed on the surface of Mars and was then unable to continue its progress is now being diagnosed remotely. "There are various possible explanations, to which we will have to react differently," says Matthias Grott, a planetary researcher and the HP³ Project Scientist. A possible explanation is that the 'Mole' has created a cavity around itself and is no longer sufficiently constrained by the friction between its body and the surrounding sand.
Another type of sand
- In Bremen, DLR is now experimenting with a different type of sand: "Until now, our tests have been conducted using a Mars-like sand that is not very cohesive," explains Wippermann. This sand was used during earlier tests in which the 'Mole' hammered its way down a five-meter column in preparation for the mission. Now, the Mole's ground model will be tested in a box of sand that compacts quickly and in which cavities can be created by the hammering process. During some of the test runs, the researchers will also place a rock with a diameter of about 10 cm in the sand. Such an obstacle in the subsurface could also be the reason why the HP3 instrument has stopped penetrating further. In all experiments, a seismometer listens to the activity of the Earth-based 'Mole'. During the short 'diagnostic' hammering on Mars, SEIS recorded vibrations to learn more about the Mole's impact mechanism. Comparisons between the data obtained on Mars and the Earth-based tests help the researchers more closely understand the real-life situation. "Ideally, we will be able to reconstruct the processes on Mars as accurately as possible."
'Moles' on Earth as guinea pigs
- The next steps will follow once the scientists know what caused the progress of the 'Mole' to come to a halt on 28 February 2019. Possible measures to allow the instrument to hammer further into the ground must then be meticulously tested and analyzed on Earth. For this reason, a replica of the HP3 instrument has been shipped to NASA's Jet Propulsion Laboratory in Pasadena, California. There, the DLR researchers' findings can be used to test the interaction of the 'Mole', the support structure and the robotic arm to determine whether, for example, lifting or moving the external structure is the correct solution. "I think that it will be a few weeks before any further actions are carried out on Mars," says Grott. The break in activities for the Mars Mole will only come to an end once a solution has been found for the Earth-based 'Moles'.
• On 28 February 2019, the DLR (German Aerospace Center) 'Mole' (HP3) fully automatically hammered its way into the Martian subsurface for the first time. In a first step, it penetrated to a depth between 18 and 50 cm into the Martian soil with 4000 hammer blows over a period of four hours. "On its way into the depths, the mole seems to have hit a stone, tilted about 15 degrees and pushed it aside or passed it," reports Tilman Spohn, Principal Investigator of the HP3 experiment. "The Mole then worked its way up against another stone at an advanced depth until the planned four-hour operating time of the first sequence expired. Tests on Earth showed that the rod-shaped penetrometer is able to push smaller stones to the side, which is very time-consuming. 46)
- After a cooling-off period, the researchers will command a second four-hour hammering sequence. In the following weeks, with further intervals, they want to reach a target depth of three to five meters on sufficiently porous ground. The Mole will pull a 5 m long tether equipped with temperature sensors into the Martian soil behind it. The cable is equipped with 14 temperature sensors in order to measure the temperature distribution with depth and its change with time after reaching the target depth and thus the heat flow from the interior of Mars.
Figure 35: For the first time since the astronaut mission Apollo 17 in 1972, heat flow measurements will be carried out on another celestial body using a drilling mechanism. The main aim of the experiment is to be able to determine the thermal state of the interior of Mars using thermal flow measurements taken beneath the surface. Models of Mars’ formation, chemical composition and inner structure can be checked and refined on the basis of this data. The measurements from Mars can also be used to draw conclusions about Earth’s early development (video credit: DLR)
- Hammering, cooling, heating, measuring. The probe pauses after each step for about three Mars days (sols). It cools down for about two days after several hours of hammering, which causes friction and generates heat. Then, it measures the thermal conductivity of the soil at a sufficient depth for one day. “For this purpose, a piece of foil in the shell of the Mole is heated for several hours with a known electrical power,” says DLR planetary researcher Matthias Grott. “The simultaneously measured increase in the temperature of the foil then gives us a measure of the thermal conductivity of the soil in its immediate surroundings.” In addition, the radiometer mounted on the InSight lander measures the temperature of the Martian soil on the surface, which fluctuates from some degrees above zero degrees Celsius to almost -100 degrees Celsius. Later on, once the target depth has been reached, the data from the temperature and thermal conductivity measurements, along with the radiometer data, is received at the DLR control center in Cologne, processed and then evaluated by scientists at the DLR Institute of Planetary Research.
• February 19, 2019: No matter how cold your winter has been, it's probably not as chilly as Mars. Check for yourself: Starting today, the public can get a daily weather report from NASA's InSight lander. 47)
Figure 36: This is NASA InSight's first full selfie on Mars. It displays the lander's solar panels and deck. On top of the deck are its science instruments, weather sensor booms and UHF antenna. The selfie was taken on Dec. 6, 2018 (Sol 10). The selfie is made up of 11 images which were taken by its Instrument Deployment Camera, located on the elbow of its robotic arm. Those images are then stitched together into a mosaic (image credit: NASA/JPL-Caltech)
- This public tool includes statistics on temperature, wind and air pressure recorded by InSight. Sunday's weather was typical for the lander's location during late northern winter: a high of 2 degrees Fahrenheit (-17 degrees Celsius) and low of -138 degrees Fahrenheit (-95 degrees Celsius), with a top wind speed of 37.8 mph (16.9 m/s) in a southwest direction. The tool was developed by NASA's Jet Propulsion Laboratory in Pasadena, California, with partners at Cornell University and Spain's Centro de Astrobiología. JPL leads the InSight mission.
- Through a package of sensors called the Auxiliary Payload Subsystem (APSS), InSight will provide more around-the-clock weather information than any previous mission to the Martian surface. The lander records this data during each second of every sol (a Martian day) and sends it to Earth on a daily basis. The spacecraft is designed to continue that operation for at least the next two Earth years, allowing it to study seasonal changes as well.
- The tool will be geeky fun for meteorologists while offering everyone who uses it a chance to be transported to another planet.
- "It gives you the sense of visiting an alien place," said Don Banfield of Cornell University, in Ithaca, New York, who leads InSight's weather science. "Mars has familiar atmospheric phenomena that are still quite different than those on Earth."
- Constantly collecting weather data allows scientists to detect sources of "noise" that could influence readings from the lander's seismometer and heat flow probe, its main instruments. Both are affected by Mars' extreme temperature swings. The seismometer, called the Seismic Experiment for Interior Structure (SEIS), is sensitive to air pressure changes and wind, which create movements that could mask actual marsquakes.
- "APSS will help us filter out environmental noise in the seismic data and know when we're seeing a marsquake and when we aren't," Banfield said. "By operating continuously, we'll also see a more detailed view of the weather than most surface missions, which usually collect data only intermittently throughout a sol."
- APSS includes an air pressure sensor inside the lander and two air temperature and wind sensors on the lander's deck. Under the edge of the deck is a magnetometer, provided by UCLA, which will measure changes in the local magnetic field that could also influence SEIS. It is the first magnetometer ever placed on the surface of another planet.
- InSight will provide a unique data set that will complement the weather measurements of other active missions, including NASA's Curiosity rover and orbiters circling the planet. InSight's air temperature and wind sensors are actually refurbished spares originally built for Curiosity's Rover Environmental Monitoring Station (REMS). These two east- and west-facing booms sit on the lander's deck and are called Temperature and Wind for InSight (TWINS), provided by Spain's Centro de Astrobiología.
- TWINS will be used to tell the team when strong winds could interfere with small seismic signals. But it could also be used, along with InSight's cameras, to study how much dust and sand blow around. Scientists don't know how much wind it takes to lift dust in Mars' thin atmosphere, which affects dune formation and dust storms - including planet-encircling dust storms like the one that occurred last year, effectively ending the Opportunity rover's mission.
- APSS will also help the mission team learn about dust devils that have left streaks on the planet's surface. Dust devils are essentially low-pressure whirlwinds, so InSight's air pressure sensor can detect when one is near. It's highly sensitive - 10 times more so than equipment on the Viking and Pathfinder landers - enabling the team to study dust devils from hundreds of feet (dozens of meters) away.
- "Our data has already shown there are a lot of dust devils at our location," Banfield said. "Having such a sensitive pressure sensor lets us see more of them passing by."
• February 13, 2019: NASA's InSight lander has placed its second instrument on the Martian surface. New images confirm that the HP3 (Heat Flow and Physical Properties Package) was successfully deployed on 12 February about 1 meter from InSight's seismometer, which the lander recently covered with a protective shield. HP3 measures heat moving through Mars' subsurface and can help scientists figure out how much energy it takes to build a rocky world. 48)
- Equipped with a self-hammering spike, mole, the instrument will burrow up to 5 m below the surface, deeper than any previous mission to the Red Planet. For comparison, NASA's Viking 1 lander scooped 22 cm down. The agency's Phoenix lander, a cousin of InSight, scooped 18 cm down.
- "We're looking forward to breaking some records on Mars," said HP3 Principal Investigator Tilman Spohn of the German Aerospace Center (DLR), which provided the heat probe for the InSight mission. "Within a few days, we'll finally break ground using a part of our instrument we call the mole."
- HP3 looks a bit like an automobile jack but with a vertical metal tube up front to hold the 40-centimeter-long) mole. A tether connects HP3's support structure to the lander, while a tether attached to the top of the mole features heat sensors to measure the temperature of the Martian subsurface. Meanwhile, heat sensors in the mole itself will measure the soil's thermal conductivity - how easily heat moves through the subsurface.
- "Our probe is designed to measure heat coming from the inside of Mars," said InSight Deputy Principal Investigator Sue Smrekar of NASA's Jet Propulsion Laboratory in Pasadena, California. "That's why we want to get it belowground. Temperature changes on the surface, both from the seasons and the day-night cycle, could add 'noise' to our data."
- The mole stops about every 51 cm to warm up for roughly four days; the sensors check how rapidly this happens, which tells scientists the conductivity of the soil. Between the careful burrowing action, the pauses and the time required for the science team to send commands to the instrument, more than a month will go by before the mole reaches its maximum depth. If the mole extends as far as it can go, the team will need only a few months of data to figure out Mars' internal temperature.
- If the mole encounters a large rock before reaching at least 3 meters down, the team will need a full Martian year (two Earth years) to filter noise out of their data. This is one reason the team carefully selected a landing site with few rocks and why it spent weeks choosing where to place the instrument.
- "We picked the ideal landing site, with almost no rocks at the surface," said JPL's Troy Hudson, a scientist and engineer who helped design HP3. "That gives us reason to believe there aren't many large rocks in the subsurface. But we have to wait and see what we'll encounter underground."
- However deep it gets, there's no debating that the mole is a feat of engineering.
- "That thing weighs less than a pair of shoes, uses less power than a Wi-Fi router and has to dig at least 3 meters on another planet," Hudson said. "It took so much work to get a version that could make tens of thousands of hammer strokes without tearing itself apart; some early versions failed before making it to 5 meters, but the version we sent to Mars has proven its robustness time and again."
Figure 37: NASA's InSight lander set its heat probe, called the Heat and Physical Properties Package (HP3), on the Martian surface on Feb. 12 (image credit: NASA/JPL-Caltech/DLR)
• February 04, 2019: For the past several weeks, NASA's InSight lander has been making adjustments to the seismometer it set on the Martian surface on Dec. 19. Now it's reached another milestone by placing a domed shield over the seismometer to help the instrument collect accurate data. The seismometer will give scientists their first look at the deep interior of the Red Planet, helping them understand how it and other rocky planets are formed. 49)
- The Wind and Thermal Shield helps protect the supersensitive instrument from being shaken by passing winds, which can add "noise" to its data. The dome's aerodynamic shape causes the wind to press it toward the planet's surface, ensuring it won't flip over. A skirt made of chain mail and thermal blankets rings the bottom, allowing it to settle easily over any rocks, though there are few at InSight's location.
- An even bigger concern for InSight's seismometer - called the Seismic Experiment for Interior Structure (SEIS) - is temperature change, which can expand and contract metal springs and other parts inside the seismometer. Where InSight landed, temperatures fluctuate by about 170 degrees Fahrenheit (94 degrees Celsius) over the course of a Martian day, or sol.
- "Temperature is one of our biggest bugaboos," said InSight Principal Investigator Bruce Banerdt of NASA's Jet Propulsion Laboratory in Pasadena, California. JPL leads the InSight mission and built the Wind and Thermal Shield. "Think of the shield as putting a cozy over your food on a table. It keeps SEIS from warming up too much during the day or cooling off too much at night. In general, we want to keep the temperature as steady as possible."
- On Earth, seismometers are often buried about four feet (1.2 meters) underground in vaults, which helps keep the temperature stable. InSight can't build a vault on Mars, so the mission relies on several measures to protect its seismometer. The shield is the first line of defense.
- A second line of defense is SEIS itself, which is specially engineered to correct for wild temperature swings on the Martian surface. The seismometer was built so that as some parts expand and contract, others do so in the opposite direction to partially cancel those effects. Additionally, the instrument is vacuum-sealed in a titanium sphere that insulates its sensitive insides and reduces the influence of temperature.
- But even that isn't quite enough. The sphere is enclosed within yet another insulating container - a copper-colored hexagonal box visible during SEIS's deployment. The walls of this box are honeycombed with cells that trap air and keep it from moving. Mars provides an excellent gas for this insulation: Its thin atmosphere is primarily composed of carbon dioxide, which at low pressure is especially slow to conduct heat.
- With these three insulating barriers, SEIS is well-protected from thermal "noise" seeping into the data and masking the seismic waves that InSight's team wants to study. Finally, most additional interference from the Martian environment can be detected by InSight's weather sensors, then filtered out by mission scientists.
- With the seismometer on the ground and covered, InSight's team is readying for its next step: deploying the heat flow probe, called the Heat Flow and Physical Properties Package (HP3), onto the Martian surface. That's expected to happen next week.
Figure 38: NASA's InSight lander deployed its Wind and Thermal Shield on Feb. 2, 2019 (sol 66). The shield covers InSight's seismometer, which was set down onto the Martian surface on Dec. 19, 2018. This image was taken by the Instrument Deployment Camera on the lander's robotic arm (image credit: NASA/JPL-Caltech)
• December 19, 2018: NASA's InSight lander has deployed its first instrument onto the surface of Mars, completing a major mission milestone. New images from the lander show the seismometer on the ground, its copper-colored covering faintly illuminated in the Martian dusk. It looks as if all is calm and all is bright for InSight, heading into the end of the year. 50)
- "InSight's timetable of activities on Mars has gone better than we hoped," said InSight Project Manager Tom Hoffman, who is based at NASA's Jet Propulsion Laboratory in Pasadena, California. "Getting the seismometer safely on the ground is an awesome Christmas present."
- The InSight team has been working carefully toward deploying its two dedicated science instruments onto Martian soil since landing on Mars on Nov. 26. Meanwhile, the Rotation and Interior Structure Experiment (RISE), which does not have its own separate instrument, has already begun using InSight's radio connection with Earth to collect preliminary data on the planet's core. Not enough time has elapsed for scientists to deduce what they want to know - scientists estimate they might have some results starting in about a year.
- To deploy the seismometer SEIS (Seismic Experiment for Interior Structure) and the heat probe HP3 (Heat Flow and Physical Properties Probe), engineers first had to verify the robotic arm that picks up and places InSight's instruments onto the Martian surface was working properly. Engineers tested the commands for the lander, making sure a model in the test bed at JPL deployed the instruments exactly as intended. Scientists also had to analyze images of the Martian terrain around the lander to figure out the best places to deploy the instruments.
- On Tuesday, Dec. 18, InSight engineers sent up the commands to the spacecraft. On Wednesday, Dec. 19, the seismometer was gently placed onto the ground directly in front of the lander, about as far away as the arm can reach - 1.636 m away.
- "Seismometer deployment is as important as landing InSight on Mars," said InSight Principal Investigator Bruce Banerdt, also based at JPL. "The seismometer is the highest-priority instrument on InSight: We need it in order to complete about three-quarters of our science objectives."
- The seismometer allows scientists to peer into the Martian interior by studying ground motion - also known as marsquakes. Each marsquake acts as a kind of flashbulb that illuminates the structure of the planet's interior. By analyzing how seismic waves pass through the layers of the planet, scientists can deduce the depth and composition of these layers.
- "Having the seismometer on the ground is like holding a phone up to your ear," said Philippe Lognonné, principal investigator of SEIS from IPGP (Institut de Physique du Globe de Paris) and Paris Diderot University. "We're thrilled that we're now in the best position to listen to all the seismic waves from below Mars' surface and from its deep interior."
- In the coming days, the InSight team will work on leveling the seismometer, which is sitting on ground that is tilted 2 to 3 degrees. The first seismometer science data should begin to flow back to Earth after the seismometer is in the right position.
- But engineers and scientists at JPL, the French national space agency CNES (Centre National d'Études Spatiales) and other institutions affiliated with the SEIS team will need several additional weeks to make sure the returned data are as clear as possible. For one thing, they will check and possibly adjust the seismometer's long, wire-lined tether to minimize noise that could travel along it to the seismometer. Then, in early January, engineers expect to command the robotic arm to place the Wind and Thermal Shield over the seismometer to stabilize the environment around the sensors.
- Assuming that there are no unexpected issues, the InSight team plans to deploy the heat probe onto the Martian surface by late January. HP3 will be on the east side of the lander's work space, roughly the same distance away from the lander as the seismometer.
- For now, though, the team is focusing on getting those first bits of seismic data (however noisy) back from the Martian surface.
- "We look forward to popping some Champagne when we start to get data from InSight's seismometer on the ground," Banerdt added. "I have a bottle ready for the occasion."
Figure 39: NASA's InSight lander placed its seismometer on Mars on Dec. 19, 2018. This was the first time a seismometer had ever been placed onto the surface of another planet (image credit: NASA/JPL-Caltech)
• December 11, 2018: NASA's InSight lander isn't camera-shy. The spacecraft used a camera on its robotic arm to take its first selfie - a mosaic made up of 11 images. This is the same imaging process used by NASA's Curiosity rover mission, in which many overlapping pictures are taken and later stitched together. Visible in the selfie are the lander's solar panel and its entire deck, including its science instruments. 51)
Figure 40: This is NASA InSight's first selfie on Mars. It displays the lander's solar panels and deck. On top of the deck are its science instruments, weather sensor booms and UHF antenna (image credit: NASA/JPL-Caltech)
- Mission team members have also received their first complete look at InSight's "workspace" - the approximately 4 x2 m crescent of terrain directly in front of the spacecraft (Figure 41). This image is also a mosaic composed of 52 individual photos.
Figure 41: This mosaic, composed of 52 individual images from NASA's InSight lander, shows the workspace where the spacecraft will eventually set its science instruments (image credit: NASA/JPL-Caltech)
- In the coming weeks, scientists and engineers will go through the painstaking process of deciding where in this workspace the spacecraft's instruments should be placed. They will then command InSight's robotic arm to carefully set the seismometer SEIS (Seismic Experiment for Interior Structure) and heat-flow probe HP3 (Heat Flow and Physical Properties Package) in the chosen locations. Both work best on level ground, and engineers want to avoid setting them on rocks larger than about 1.5 cm.
- "The near-absence of rocks, hills and holes means it'll be extremely safe for our instruments," said InSight's Principal Investigator Bruce Banerdt of NASA's Jet Propulsion Laboratory in Pasadena, California. "This might seem like a pretty plain piece of ground if it weren't on Mars, but we're glad to see that."
- InSight's landing team deliberately chose a landing region in Elysium Planitia that is relatively free of rocks. Even so, the landing spot turned out even better than they hoped. The spacecraft sits in what appears to be a nearly rock-free "hollow" - a depression created by a meteor impact that later filled with sand. That should make it easier for one of InSight's instruments, the heat-flow probe, to bore down to its goal of 5 meters below the surface.
• December 6, 2018: New images from NASA's Mars InSight lander show its robotic arm is ready to do some lifting. 52)
- With a reach of nearly 2 meters, the arm will be used to pick up science instruments from the lander's deck, gently setting them on the Martian surface at Elysium Planitia, the lava plain where InSight touched down on 26 November.
- But first, the arm will use its Instrument Deployment Camera, located on its elbow, to take photos of the terrain in front of the lander. These images will help mission team members determine where to set InSight's seismometer and heat flow probe - the only instruments ever to be robotically placed on the surface of another planet.
- "Today we can see the first glimpses of our workspace," said Bruce Banerdt, the mission's principal investigator at NASA's Jet Propulsion Laboratory in Pasadena, California. "By early next week, we'll be imaging it in finer detail and creating a full mosaic."
- Another camera, called the Instrument Context Camera, is located under the lander's deck. It will also offer views of the workspace, though the view won't be as pretty.
- "We had a protective cover on the Instrument Context Camera, but somehow dust still managed to get onto the lens," said Tom Hoffman of JPL, InSight's project manager. "While this is unfortunate, it will not affect the role of the camera, which is to take images of the area in front of the lander where our instruments will eventually be placed."
- Placement is critical, and the team is proceeding with caution. Two to three months could go by before the instruments have been situated and calibrated.
- Over the past week and a half, mission engineers have been testing those instruments and spacecraft systems, ensuring they're in working order. A couple instruments are even recording data: a drop in air pressure, possibly caused by a passing dust devil, was detected by the pressure sensor. This, along with a magnetometer and a set of wind and temperature sensors, are part of a package called the Auxiliary Payload Sensor Subsystem, which will collect meteorological data.
- More images from InSight's arm were scheduled to come down this past weekend. However, imaging was momentarily interrupted, resuming the following day. During the first few weeks in its new home, InSight has been instructed to be extra careful, so anything unexpected will trigger what's called a fault. Considered routine, it causes the spacecraft to stop what it is doing and ask for help from operators on the ground.
- "We did extensive testing on Earth. But we know that everything is a little different for the lander on Mars, so faults are not unusual," Hoffman said. "They can delay operations, but we're not in a rush. We want to be sure that each operation that we perform on Mars is safe, so we set our safety monitors to be fairly sensitive initially."
- Spacecraft engineers had already factored extra time into their estimates for instrument deployment to account for likely delays caused by faults. The mission's primary mission is scheduled for two Earth years, or one Mars year - plenty of time to gather data from the Red Planet's surface.
Figure 42: This image from InSight's robotic-arm mounted Instrument Deployment Camera shows the instruments on the spacecraft's deck, with the Martian surface of Elysium Planitia in the background (image credit: NASA/JPL-Caltech)
Legend to Figure 42: The color-calibrated picture was acquired on 4 December 2018 (Sol 8). In the foreground, a copper-colored hexagonal cover protects the Seismic Experiment for Interior Structure instrument (SEIS), a seismometer that will measure marsquakes. The gray dome behind SEIS is the wind and thermal shield, which will be placed over SEIS. To the left is a black cylindrical instrument, the Heat Flow and Physical Properties Probe (HP3). HP3 will drill up to 5 meters below the Martian surface, measuring heat released from the interior of the planet. Above the deck is InSight's robotic arm, with the stowed grapple directly facing the camera. To the right can be seen a small portion of one of the two solar panels that help power InSight and part of the UHF communication antenna.
Figure 43: A partial view of the deck of NASA's InSight lander, where it stands on the Martian plains Elysium Planitia. The color-calibrated image was received on 4 December 2018 (Sol 8). InSight's robotic arm with its stowed grapple can be seen above the deck, and jutting out from the front of the deck is one of the boxy attitude control system thrusters that helped control the spacecraft's landing. The circular silver inset of the propellant tank can also be seen in the middle of the image, as well as one of the connections for the aeroshell and parachute, which looks like a cupholder in the foreground. Next to the propellant tank is the UHF antenna, which helps the lander communicate with Earth. In the background, part of one of InSight's solar panels is visible (image credit: NASA/JPL-Caltech)
• November 29, 2018: After safely landing on Mars following its nearly seven month journey, NASA has released the first pictures taken by its InSight spacecraft, which has opened it solar arrays to charge batteries. 53)
- The $993 million lander, which landed on Monday and appears to be in good shape, will soon begin unfolding its robotic arm and deploying its quake-sensors on the Martian surface.
- NASA engineers are planning to begin work with its robotic arm soon, but are proceeding with caution. The arm has five mechanical fingers to help it lift out and place its two instruments on Martian soil in the coming few months.
- "Slowly releasing all my pent-up tension, starting with loosening my grapple, as these before-and-after pics show," said the NASAInSight Twitter account. "Until I'm ready to stretch my arm out, my camera angles will be the same."
- InSight is equipped with two full-color cameras and has already sent back six shots since touching down. The waist-high spacecraft will stay in place for the two-year duration of its mission.
- NASA has not said anything about the condition of the other instruments on board, which include a French-made seismometer to study Marsquakes and a German self-hammering mole to measure heat's escape from the planet.
- NASA did say its solar arrays have deployed, which is good news since the lander runs on solar energy.
- In Paris, the French CERN said everything seems fine for the moment, and that it is up to NASA to communicate with the SEIS quake-sensing instrument.
• November 26, 2018: Mars has just received its newest robotic resident. NASA's InSight (Interior Exploration using Seismic Investigations, Geodesy and Heat Transport) lander successfully touched down on the Red Planet after an almost seven-month, 300-million-mile (458-million-kilometer) journey from Earth. 54) 55)
- InSight's two-year mission will be to study the deep interior of Mars to learn how all celestial bodies with rocky surfaces, including Earth and the Moon, formed.
Figure 44: Tom Hoffman, InSight Project Manager, NASA JPL, left, and Sue Smrekar, InSight deputy principal investigator, NASA JPL, react after receiving confirmation that the Mars InSight lander successfully touched down on the surface of Mars, Monday, Nov. 26, 2018 inside the Mission Support Area at NASA's Jet Propulsion Laboratory in Pasadena, California (image credit: NASA, Bill Ingalls)
- InSight launched from Vandenberg Air Force Base in California on 5 May 2018. The lander touched down Monday, Nov. 26, near Mars' equator on the western side of a flat, smooth expanse of lava called Elysium Planitia, with a signal affirming a completed landing sequence at 11:52:59 a.m. PST (2:52:59 p.m. EST) or at 19:52:59 UTC.
- "Today, we successfully landed on Mars for the eighth time in human history," said NASA Administrator Jim Bridenstine. "InSight will study the interior of Mars and will teach us valuable science as we prepare to send astronauts to the Moon and later to Mars. This accomplishment represents the ingenuity of America and our international partners, and it serves as a testament to the dedication and perseverance of our team. The best of NASA is yet to come, and it is coming soon."
- The landing signal was relayed to NASA's Jet Propulsion Laboratory (JPL) in Pasadena, California, via NASA's two small experimental MarCO (Mars Cube One) CubeSats, which launched on the same rocket as InSight and followed the lander to Mars. They are the first CubeSats sent into deep space. After successfully carrying out a number of communications and in-flight navigation experiments, the twin MarCOs were set in position to receive transmissions during InSight's entry, descent and landing.
Figure 45: The MarCO-B CubeSat took this image of Mars from about 4,700 miles (6,000 km) away during its flyby of the Red Planet on Nov. 26, 2018. MarCO-B was flying by Mars with its twin, MarCO-A, to attempt to serve as communications relays for NASA’s InSight spacecraft as it landed on Mars (image credit: NASA/JPL-Caltech)
From Fast to Slow
- "We hit the Martian atmosphere at 12,300 mph (19,800 km/hr), and the whole sequence to touching down on the surface took only six-and-a-half minutes," said InSight project manager Tom Hoffman at JPL. "During that short span of time, InSight had to autonomously perform dozens of operations and do them flawlessly - and by all indications that is exactly what our spacecraft did."
- Confirmation of a successful touchdown is not the end of the challenges of landing on the Red Planet. InSight's surface-operations phase began a minute after touchdown. One of its first tasks is to deploy its two decagonal solar arrays, which will provide power. That process begins 16 minutes after landing and takes another 16 minutes to complete.
- The InSight team expects a confirmation later Monday that the spacecraft's solar panels successfully deployed. Verification will come from NASA's Odyssey spacecraft, currently orbiting Mars. That signal is expected to reach InSight's mission control at JPL about five-and-a-half hours after landing.
- "We are solar powered, so getting the arrays out and operating is a big deal," said Tom Hoffman at JPL. "With the arrays providing the energy we need to start the cool science operations, we are well on our way to thoroughly investigate what's inside of Mars for the very first time."
- InSight will begin to collect science data within the first week after landing, though the teams will focus mainly on preparing to set InSight's instruments on the Martian ground. At least two days after touchdown, the engineering team will begin to deploy InSight's 1.8-meter-long robotic arm so that it can take images of the landscape.
- "Landing was thrilling, but I'm looking forward to the drilling," said InSight principal investigator Bruce Banerdt of JPL. "When the first images come down, our engineering and science teams will hit the ground running, beginning to plan where to deploy our science instruments. Within two or three months, the arm will deploy the mission's main science instruments, the Seismic Experiment for Interior Structure (SEIS) and Heat Flow and Physical Properties Package (HP3) instruments."
- InSight will operate on the surface for one Martian year, plus 40 Martian days, or sols, until Nov. 24, 2020. The mission objectives of the two small MarCOs which relayed InSight's telemetry was completed after their Martian flyby.
- "That's one giant leap for our intrepid, briefcase-sized robotic explorers," said Joel Krajewski, MarCO project manager at JPL. "I think CubeSats have a big future beyond Earth's orbit, and the MarCO team is happy to trailblaze the way."
- With InSight's landing at Elysium Planitia, NASA has successfully soft-landed a vehicle on the Red Planet eight times.
- "Every Mars landing is daunting, but now with InSight safely on the surface we get to do a unique kind of science on Mars," said JPL director Michael Watkins. "The experimental MarCO CubeSats have also opened a new door to smaller planetary spacecraft. The success of these two unique missions is a tribute to the hundreds of talented engineers and scientists who put their genius and labor into making this a great day."
Figure 46: NASA's InSight Mars lander acquired this image of the area in front of the lander using its lander-mounted, Instrument Context Camera (ICC). This image was acquired on Nov. 26, 2018, Sol 0 of the InSight mission where the local mean solar time for the image exposures was 13:34:21. Each ICC image has a field of view of 124 x 124 degrees (image credit: NASA/JPL-CalTech)
• November 21,2018: A European antenna in Australia will soon be tracking a US mission currently preparing to land on Mars. ESA’s New Norcia antenna is situated in the red and dusty desert of Western Australia, seen here under the twinkling lights of the Milky Way. From here, it will provide support to NASA’s InSight lander, which is scheduled to touch down on the similarly dry and dusty landscape of the Red Planet, at 20:00 UTC (21:00 CET) on Monday 26 November. 56)
- About 12 hours before the landing, and during the very last ‘Target Correction Maneuver’ before Insight enters the martian atmosphere to land, this 35 m deep space antenna will make contact with the lander.
- A crucial part of ESA’s Estrack network, the New Norcia antenna routinely supports ESA missions voyaging throughout the Solar System, including Mars Express, ExoMars Trace Gas Orbiter (TGO), Gaia and BepiColombo.
- ESA’s TGO will join with NASA orbiters to pick up data signals from InSight once it has landed, and relay these back to Earth, providing the first-ever routine data relay support between missions of different agencies at Mars.
• November 21, 2018: NASA's InSight spacecraft is on track for a soft touchdown on the surface of the Red Planet on Nov. 26, the Monday after Thanksgiving. But it's not going to be a relaxing weekend of turkey leftovers, football and shopping for the InSight mission team. Engineers will be keeping a close eye on the stream of data indicating InSight's health and trajectory, and monitoring Martian weather reports to figure out if the team needs to make any final adjustments in preparation for landing, only five days away. 57)
Legend to Figure 47: EDL begins when the spacecraft reaches the Martian atmosphere, about 80 miles (about 128 km) above the surface, and ends with the lander safe and sound on the surface of Mars six minutes later.
- "Landing on Mars is hard. It takes skill, focus and years of preparation," said Thomas Zurbuchen, associate administrator for the Science Mission Directorate at NASA Headquarters in Washington. "Keeping in mind our ambitious goal to eventually send humans to the surface of the Moon and then Mars, I know that our incredible science and engineering team - the only in the world to have successfully landed spacecraft on the Martian surface - will do everything they can to successfully land InSight on the Red Planet."
- InSight, the first mission to study the deep interior of Mars, blasted off from Vandenberg Air Force Base in Central California on May 5, 2018. It has been an uneventful flight to Mars, and engineers like it that way. They will get plenty of excitement when InSight hits the top of the Martian atmosphere at 12,300 mph (19,800 km/h) and slows down to 5 mph (8 km/h) - about human jogging speed - before its three legs touch down on Martian soil. That extreme deceleration has to happen in just under seven minutes.
- ”There's a reason engineers call landing on Mars 'seven minutes of terror,'" said Rob Grover, InSight's EDL lead, based at NASA's Jet Propulsion Laboratory in Pasadena, California. "We can't joystick the landing, so we have to rely on the commands we pre-program into the spacecraft. We've spent years testing our plans, learning from other Mars landings and studying all the conditions Mars can throw at us. And we're going to stay vigilant till InSight settles into its home in the Elysium Planitia region."
- One way engineers may be able to confirm quickly what activities InSight has completed during those seven minutes of terror is if the experimental CubeSat mission known as Mars Cube One (MarCO) relays InSight data back to Earth in near-real time during their flyby on Nov. 26. The two MarCO spacecraft (A and B) are making good progress toward their rendezvous point, and their radios have already passed their first deep-space tests.
- "Just by surviving the trip so far, the two MarCO satellites have made a giant leap for CubeSats," said Anne Marinan, a MarCO systems engineer based at JPL. "And now we are gearing up for the MarCOs' next test - serving as a possible model for a new kind of interplanetary communications relay."
- If all goes well, the MarCOs may take a few seconds to receive and format the data before sending it back to Earth at the speed of light. This would mean engineers at JPL and another team at Lockheed Martin Space in Denver would be able to tell what the lander did during EDL approximately eight minutes after InSight completes its activities. Without MarCO, InSight's team would need to wait several hours for engineering data to return via the primary communications pathways - relays through NASA's Mars Reconnaissance Orbiter and Mars Odyssey orbiter.
- Once engineers know that the spacecraft has touched down safely in one of several ways they have to confirm this milestone and that InSight's solar arrays have deployed properly, the team can settle into the careful, three-month-long process of deploying science instruments.
- "Landing on Mars is exciting, but scientists are looking forward to the time after InSight lands," said Lori Glaze, acting director of the Planetary Science Division at NASA Headquarters. "Once InSight is settled on the Red Planet and its instruments are deployed, it will start collecting valuable information about the structure of Mars' deep interior - information that will help us understand the formation and evolution of all rocky planets, including the one we call home."
- "Previous missions haven't gone more than skin-deep at Mars," added Sue Smrekar, the InSight mission's deputy principal investigator at JPL. "InSight scientists can't wait to explore the heart of Mars."
• November 5, 2018: No doubt about it, NASA explores some of the most awe-inspiring locations in our solar system and beyond. Once seen, who can forget the majesty of astronaut Jim Irwin standing before the stark beauty of the Moon's Hadley Apennine mountain range, of the Hubble Space Telescope's gorgeous "Pillars of Creation" or Cassini's magnificent mosaic of Saturn? 58)
- Mars also plays a part in this visually compelling equation, with the high-definition imagery from the Curiosity rover of the ridges and rounded buttes at the base of Mount Sharp bringing to mind the majesty of the American Southwest. That said, Elysium Planitia – the site chosen for the 26 November landing of NASA's InSight mission to Mars – will more than likely never be mentioned with those above because it is, well, plain.
- "If Elysium Planitia were a salad, it would consist of romaine lettuce and kale – no dressing," said InSight principal investigator Bruce Banerdt at NASA's Jet Propulsion Laboratory in Pasadena, California. "If it were an ice cream, it would be vanilla."
- The landing site of NASA's next Mars mission may very well look like a stadium parking lot, but that is the way the Interior Exploration using Seismic Investigations, Geodesy and Heat Transport (InSight) project likes it.
- "Previous missions to the Red Planet have investigated its surface by studying its canyons, volcanoes, rocks and soil," said Banerdt. "But the signatures of the planet's formation processes can be found only by sensing and studying evidence buried far below the surface. It is InSight's job to study the deep interior of Mars, taking the planet's vital signs – its pulse, temperature and reflexes."
- Taking those vital signs will help the InSight science team look back to a time when the rocky planets of the solar system formed. The investigations will depend on three instruments:
- A six-sensor seismometer called the Seismic Experiment for Interior Structure (SEIS) will record seismic waves traveling through the interior structure of the planet. Studying seismic waves will tell scientists what might be creating the waves. (On Mars, scientists suspect that the culprits may be marsquakes or meteorites striking the surface.)
- The mission's Heat Flow and Physical Properties Package (HP3) will burrow deeper than any other scoop, drill or probe on Mars before to gauge how much heat is flowing out of the planet. Its observations will shed light on whether Earth and Mars are made of the same stuff.
- Finally, InSight's Rotation and Interior Structure Experiment (RISE) experiment will use the lander's radios to assess the wobble of Mars' rotation axis, providing information about the planet's core.
- For InSight to do its work, the team needed a landing site that checked off several boxes, because as a three-legged lander – not a rover – InSight will remain wherever it touches down.
- "Picking a good landing site on Mars is a lot like picking a good home: It's all about location, location, location," said Tom Hoffman, InSight project manager at JPL. "And for the first time ever, the evaluation for a Mars landing site had to consider what lay below the surface of Mars. We needed not just a safe place to land, but also a workspace that's penetrable by our 5 meter heat-flow probe."
- The site also needs to be bright enough and warm enough to power the solar cells while keeping its electronics within temperature limits for an entire Martian year (26 Earth months).
- So the team focused on a band around the equator, where the lander's solar array would have adequate sunlight to power its systems year-round. Finding an area that would be safe enough for InSight to land and then deploy its solar panels and instruments without obstructions took a little longer.
- "The site has to be a low-enough elevation to have sufficient atmosphere above it for a safe landing, because the spacecraft will rely first on atmospheric friction with its heat shield and then on a parachute digging into Mars' tenuous atmosphere for a large portion of its deceleration," said Hoffman. "And after the chute has fallen away and the braking rockets have kicked in for final descent, there needs to be a flat expanse to land on – not too undulating and relatively free of rocks that could tip the tri-legged Mars lander."
- Of 22 sites considered, only Elysium Planitia, Isidis Planitia and Valles Marineris met the basic engineering constraints. To grade the three remaining contenders, reconnaissance images from NASA's Mars orbiters were scoured and weather records searched. Eventually, Isidis Planitia and Valles Marineris were ruled out for being too rocky and windy.
- That left the 81 mile long, 17mile wide (130 km long, 27 km wide) landing ellipse on the western edge of a flat, smooth expanse of lava plain.
Figure 48: The landing site for InSight, in relation to landing sites for seven previous missions, is shown on a topographic map of Mars ( image credit: NASA/JPL-Caltech)
- "If you were a Martian coming to explore Earth's interior like we are exploring Mars' interior, it wouldn't matter if you put down in the middle of Kansas or the beaches of Oahu," said Banerdt. "While I'm looking forward to those first images from the surface, I am even more eager to see the first data sets revealing what is happening deep below our landing pads. The beauty of this mission is happening below the surface. Elysium Planitia is perfect."
- After a 205-day journey that began on 5 May 2018, NASA's InSight mission will touch down on Mars on 26 November a little before 3 p.m. EST (12 p.m. PST). Its solar panels will unfurl within a few hours of touchdown. Mission engineers and scientists will take their time assessing their "workspace" prior to deploying SEIS and HP3 on the surface – about three months after landing – and begin the science in earnest.
- InSight was the 12th selection in NASA's series of Discovery-class missions. Created in 1992, the Discovery Program sponsors frequent, cost-capped solar system exploration missions with highly focused scientific goals.
Figure 49: This map shows the single area under continuing evaluation as the InSight mission's Mars landing site, as of a year before the mission's May 2016 launch. The finalist ellipse marked is within the northern portion of flat-lying Elysium Planitia about four degrees north of Mars' equator (image credit: NASA/JPL-Caltech)
- JPL manages InSight for NASA's Science Mission Directorate. InSight is part of NASA's Discovery Program, managed by the agency's Marshall Space Flight Center in Huntsville, Alabama. Lockheed Martin Space in Denver built the InSight spacecraft, including its cruise stage and lander, and supports spacecraft operations for the mission.
- A number of European partners, including France's Centre National d'Études Spatiales (CNES) and the German Aerospace Center (DLR), support the InSight mission. CNES provided the SEIS instrument, with significant contributions from the Max Planck Institute for Solar System Research (MPS) in Germany, the Swiss Institute of Technology (ETH) in Switzerland, Imperial College and Oxford University in the United Kingdom, and JPL. DLR provided the HP3 instrument.
• October 24, 2018: After touching down in November, NASA's InSight spacecraft will spread its solar panels, unfold a robotic arm ... and stay put. Unlike the space agency's rovers, InSight is a lander designed to study an entire planet from just one spot. This sedentary science allows InSight to detect geophysical signals deep below the Martian surface, including marsquakes and heat. Scientists will also be able to track radio signals from the stationary spacecraft, which vary based on the wobble in Mars' rotation. Understanding this wobble could help solve the mystery of whether the planet's core is solid. 59)
- Here are five things to know about how InSight conducts its science.
1) InSight Can Measure Quakes Anywhere on the Planet
Quakes on Earth are usually detected using networks of seismometers. InSight has only one - called SEIS (Seismic Experiment for Interior Structure) - so its science team will use some creative measurements to analyze seismic waves as they occur anywhere on the planet.
SEIS will measure seismic waves from marsquakes and meteorite strikes as they move through Mars. The speed of those waves changes depending on the material they're traveling through, helping scientists deduce what the planet's interior is made of.
Seismic waves come in a surprising number of flavors. Some vibrate across a planet's surface, while others ricochet off its center. They also move at different speeds. Seismologists can use each type as a tool to triangulate where and when a seismic event has happened. — This means InSight could have landed anywhere on Mars and, without moving, gathered the same kind of science.
2) InSight's Seismometer Needs Peace and Quiet
Seismometers are touchy by nature. They need to be isolated from "noise" in order to measure seismic waves accurately. SEIS is sensitive enough to detect vibrations smaller than the width of a hydrogen atom. It will be the first seismometer ever set on the Martian surface, where it will be thousands of times more accurate than seismometers that sat atop the Viking landers.
To take advantage of this exquisite sensitivity, engineers have given SEIS a shell: a wind-and-thermal shield that InSight's arm will place over the seismometer. This protective dome presses down when wind blows over it; a Mylar-and-chainmail skirt keeps wind from blowing in. It also gives SEIS a cozy place to hide away from Mars' intense temperature swings, which can create minute changes in the instrument's springs and electronics.
3) InSight Has a Self-Hammering Nail
Have you ever tried to hammer a nail? Then you know holding it steady is key. InSight carries a nail that also needs to be held steady. This unique instrument, called HP3 (Heat Flow and Physical Properties Package), holds a spike attached to a long tether. A mechanism inside the spike will hammer it up to 5 meters underground, dragging out the tether, which is embedded with heat sensors.
At that depth, it can detect heat trapped inside Mars since the planet first formed. That heat shaped the surface with volcanoes, mountain ranges and valleys. It may even have determined where rivers ran early in Mars' history.
4) InSight Can Land in a Safe Spot
Because InSight needs stillness - and because it can collect seismic and heat data from anywhere on the planet - the spacecraft is free to land in the safest location possible.
InSight's team selected a location on Mars' equator called Elysium Planitia - as flat and boring a spot as any on Mars. That makes landing just a bit easier, as there's less to crash into, fewer rocks to land on and lots of sunlight to power the spacecraft. The fact that InSight doesn't use much power and should have plenty of sunlight at Mars' equator means it can provide lots of data for scientists to study.
5) InSight Can Measure Mars' Wobble
InSight has two X-band antennas on its deck that make up a third instrument, called RISE (Rotation and Interior Structure Experiment). Radio signals from RISE will be measured over months, maybe even years, to study the tiny "wobble" in the rotation of the planet. That wobble is a sign of whether Mars' core is liquid or solid - a trait that could also shed light on the planet's thin magnetic field.
Collecting detailed data on this wobble hasn't happened since Mars Pathfinder's three-month mission in 1997 (although the Opportunity rover made a few measurements in 2011 while it remained still, waiting out the winter). Every time a stationary spacecraft sends radio signals from Mars, it can help scientists improve their measurements.
• October 16, 2018: If you've ever played the claw machine at an arcade, you know how hard it can be to maneuver the metal "hand" to pick up a prize. Imagine trying to play that game when the claw is on Mars, the objects you're trying to grasp are far more fragile than a stuffed bear and all you have is a stitched-together panorama of the environment you're working in. Oh, and there might be a dust storm. 60)
- NASA's InSight lander, slated to arrive on Mars Nov. 26, 2018, will be the first mission to use a robotic arm to grasp instruments from the spacecraft and release them into place on another planet. These instruments will help scientists study the deep interior of Mars for the first time.
- "We have a lot riding on InSight's robotic arm, so we've been practicing our version of the claw game dozens of times," said Tom Hoffman, InSight's project manager at NASA's Jet Propulsion Laboratory in Pasadena, California. "The difference, of course, is that, unlike the claw machine designers, our robotic arm team works hard to allow us to win every time."
- InSight's robotic arm (called the Instrument Deployment Arm) will pick up two sensitive science packages from the spacecraft deck and gently lower them to the ground: the Heat Flow and Physical Properties Package, which will assess Mars' interior energy, and the Seismic Experiment for Interior Structure, which will study vibrations of the ground set off by marsquakes and meteorite impacts. InSight also needs to place a Wind and Thermal Shield over the seismometer, like a cloche — or rounded dish cover — at a fancy dinner service.
- ”The robotic arm has to place everything perfectly," said Ashitey Trebi-Ollennu, team lead for InSight's instrument deployment system operations at JPL. "But we like a challenge."
- Luckily, engineers didn't have to start from scratch. The JPL engineering team had in storage a leftover robotic arm — made for the Mars Surveyor 2001 lander mission that never flew. The arm wasn't as beefy as ones built for missions like the Mars Curiosity Rover, which carries more weight at the end of its arm. But the 2001 arm was designed for lifting, making it appropriate for InSight's mission. And it was long (5.9 feet, or 1.8 meters, to be exact). InSight needs to put the seismometer and heat probe a significant distance away from itself for the sensitive instruments to function optimally.
- As with any vintage machine, engineers had to refurbish the arm and customize it for InSight. They pulled it apart, replaced some pieces, relubricated it and repainted it. Engineers also added a color camera and a grapple (the claw).
- The original grapple design had two stiff "toes" emanating from a central base, which Trebi-Ollennu likens to a crow's foot. Each instrument was outfitted with a knob, or "grapple point," that resembled a lollipop with a long stem for the stiff foot to grab. In tests on sloped surfaces, the lollipop often got stuck in the toes. Given the possibility of slight slopes at the InSight landing site, engineers didn't want to take that chance.
- The second proposed design was an idea familiar to those who have seen junkyard operators maneuver crushed cars. Engineers hung a magnet on an umbilical cord from the robotic arm and put steel plates on the instruments. Tests showed, however, that dust collected on both the magnet's surface and the instruments' steel plate, decreasing the ability of the two parts to stick together. Given that InSight's landing date falls within the typical dust storm season on Mars, engineers decided against this magnet design.
- The third idea was the charm: a clawlike grapple with five metal fingers about the length of human fingers (about 2.5 inches, or 63 millimeters, long) hanging off the end of an umbilical cord to compensate for any slopes. The grapple point on each instrument resembled the original spherical lollipop, but with the top half of the sphere cut off and a shorter stem.
- An especially clever feature of this robotic hand, Trebi-Ollennu explained, is that melting of paraffin wax — a common constituent of candles and crayons — controls the opening of InSight's fingers.
- To begin the process, an actuator heats a very pure paraffin wax to 84°F (29°C), which takes about 15 minutes in the average ambient Mars temperature of about minus 60°F (minus 50°C). The wax expands as it melts and pushes out a rod that pushes on a spring that opens the fingers. When the fingers open, a microswitch turns off the heater, and the cooling, contracting wax allows the rod — and therefore the fingers — to retract. At rest, the fingers are closed so that if the hand happens to lose power, it won't drop an instrument.
- A few days after landing, InSight engineers will put the robotic arm into action. The arm will move so the camera attached to it can take images of the area around the lander site. Back on Earth, engineers will use those images to figure out where the instruments can be safely set down. They will also practice deploying the instruments in a Mars-like test bed at JPL. Once the team is confident that they have a robust plan — which could take weeks — the arm with its grapple will slowly begin to deploy those instruments for real on Mars.
- "We're looking forward to the demanding work of getting InSight's claw machine in motion," said Bruce Banerdt, InSight's principal investigator at JPL. "But the prize for the InSight team won't be a fuzzy bear. It'll be the stream of science data flowing in from precisely placed instruments — telling us what Mars is really like on the inside."
Figure 50: NASA's InSight mission tests an engineering version of the spacecraft's robotic arm in a Mars-like environment at NASA's Jet Propulsion Laboratory. The five-fingered grapple on the end of the robotic arm is lifting up the Wind and Thermal Shield, a protective covering for InSight's seismometer. The test is being conducted under reddish "Mars lighting" to simulate activities on the Red Planet (image credit: NASA/JPL-Caltech)
• August 20, 2018: NASA's InSight spacecraft, en route to a 26 November landing on Mars, passed the halfway mark on 6 August. All of its instruments have been tested and are working well. 61)
- As of 20 August, the spacecraft had covered 172 million miles (277 million kilometers) since its launch 107 days ago. In another 98 days, it will travel another 129 million miles (208 million kilometers) and touch down in Mars' Elysium Planitia region, where it will be the first mission to study the Red Planet's deep interior. InSight stands for Interior Exploration using Seismic Investigations, Geodesy and Heat Transport.
- The InSight team is using the time before the spacecraft's arrival at Mars to not only plan and practice for that critical day, but also to activate and check spacecraft subsystems vital to cruise, landing and surface operations, including the highly sensitive science instruments.
- InSight's seismometer, which will be used to detect quakes on Mars, received a clean bill of health on July 19. The SEIS (Seismic Experiment for Interior Structure) instrument is a six-sensor seismometer combining two types of sensors to measure ground motions over a wide range of frequencies. It will give scientists a window into Mars' internal activity.
- "We did our final performance checks on 19 July, which were successful," said Bruce Banerdt, principal investigator of InSight from NASA's Jet Propulsion Laboratory, Pasadena, California.
- The team also checked an instrument that will measure the amount of heat escaping from Mars. After being placed on the surface, InSight's HP3 (Heat Flow and Physical Properties Package) instrument will use a self-hammering mechanical mole burrowing to a depth of 3 to 5 meters. Measurements by sensors on the mole and on a science tether from the mole to the surface will yield the first precise determination of the amount of heat escaping from the planet's interior. The checkout consisted of powering on the main electronics for the instrument, performing checks of its instrument sensor elements, exercising some of the instrument's internal heaters, and reading out the stored settings in the electronics module.
- The third of InSight's three main investigations — RISE (Rotation and Interior Structure Experiment) — uses the spacecraft's radio connection with Earth to assess perturbations of Mars' rotation axis. These measurements can provide information about the planet's core.
- "We have been using the spacecraft's radio since launch day, and our conversations with InSight have been very cordial, so we are good to go with RISE as well," said Banerdt.
- The lander's cameras checked out fine as well, taking a spacecraft selfie of the inside of the spacecraft's backshell. InSight Project Manager Tom Hoffman from JPL said that, "If you are an engineer on InSight, that first glimpse of the heat shield blanket, harness tie-downs and cover bolts is a very reassuring sight as it tells us our Instrument Context Camera is operating perfectly. The next picture we plan to take with this camera will be of the surface of Mars."
- If all goes as planned, the camera will take the first image of Elysium Planitia minutes after InSight touches down on Mars.
- JPL manages InSight for NASA's Science Mission Directorate. InSight is part of NASA's Discovery Program, managed by the agency's Marshall Space Flight Center in Huntsville, Alabama. The InSight spacecraft, including cruise stage and lander, was built and tested by Lockheed Martin Space in Denver.
- A number of European partners, including France's Centre National d'Études Spatiales (CNES) and the German Aerospace Center (DLR), are supporting the InSight mission. CNES provided the Seismic Experiment for Interior Structure (SEIS) instrument, with significant contributions from the Max Planck Institute for Solar System Research (MPS) in Germany, the Swiss Institute of Technology (ETH) in Switzerland, Imperial College and Oxford University in the United Kingdom, and JPL. DLR provided the Heat Flow and Physical Properties Package (HP3) instrument.
• May 23, 2018: NASA's InSight lander has made its first course correction toward Mars. The lander is currently encapsulated in a protective aeroshell, which launched on top of an Atlas V 401 rocket on May 5 from Vandenberg Air Force Base in Central California. Yesterday, the spacecraft fired its thrusters for the first time to change its flight path. This activity, called a trajectory correction maneuver, will happen a maximum of six times to guide the lander to Mars. 62)
- "This first maneuver is the largest we'll conduct," said Fernando Abilleira of JPL, InSight's Deputy Mission Design and Navigation Manager. "The thrusters will fire for about 40 seconds to impart a velocity change of 3.8 m/s to the spacecraft. That will put us in the right ballpark as we aim for Mars."
- Especially at the beginning of that cruise, navigators rely on NASA's DSN (Deep Space Network ) to track the spacecraft. The DSN is a system of antennas located at three sites around the Earth. As the planet rotates, each of these sites comes into range of NASA's spacecraft, pinging them with radio signals to track their positions. The antennas also send and receive data this way.
• On 5 May 2018, ESA's 35 m-diameter deep-space radio dish at New Norcia, Western Australia, monitored NASA’s InSight spacecraft providing critical tracking support during launch and early operations on its journey to Mars. 63)
- ESA’s New Norcia station maintained contact with InSight and its two MarCOs CubeSats as backup to NASA’s own Deep Space Network ground station at Canberra, on the easterly side of the continent.
- “NASA requested our support because, at this time of year, the southern hemisphere has very good visibility of the trajectory to Mars,” explained Daniel Firre, the Agency’s ESA-NASA cross-support service manager. “This meant our Australia station was ideally located to provide back-up support to their DSN station at Canberra.”
InSight sensor/experiment complement: (SEIS, HP3, RISE, IDS, APSS)
InSight is equipped with three principal instruments designed to probe the interior of Mars–none of which will take pictures, analyze minerals, or dig up soil samples as other Mars landing missions have done. The only cameras on board InSight will be used primarily to aid in the deployment of the main science instruments.
In addition to its principal instruments, InSight will carry wind, temperature and pressure sensors to monitor atmospheric conditions at the landing sight, as well as a magnetometer to measure disturbances produced in Mars’ ionosphere.
InSight’s cameras, which are primarily for guiding the placement of the SEIS and HP3 instruments on the ground, will also serve in taking pictures of the surrounding landscape—something we have come to expect from our Mars landers and rovers, even if InSight’s main mission is to look where cameras cannot see.
SEIS (Seismic Experiment for Interior Structure) instrument
SEIS is a seismometer, supplied by France's space agency, CNES, with collaboration from the United States (JPL), the United Kingdom (Imperial College), 64) Switzerland (ETH -Swiss Federal Institute of Technology, Zürich ) and Germany (MPS- Max Planck Institute for Solar System Research). 65) Shielded from wind and with sensitivity fine enough to detect ground movements half the diameter of a hydrogen atom, it will record seismic waves from "marsquakes" or meteor impacts that reveal information about the planet's interior layers.
The objective of SEIS is to measure the pulse of Mars by studying waves created by marsquakes, thumps of meteorite impacts, and even surface vibrations generated by activity in Mars' atmosphere and by weather phenomena such as dust storms.
The SEIS instrument will be placed onto the surface of Mars. The instrument has a mass of 29.5 kg, a power consumption of up to 8.5 W, a vacuum chamber volume of 3 liters, and a data volume of ~38 Mbit/day. The PI (Principal Investigator) of SEIS is Philippe Lognonné of IPGP (Institut de Physique du Globe de Paris, or Institute of Earth Physics) of Paris, University Paris Diderot, Paris, France. 66) 67) 68) 69)
The SEIS seismometer is based on a six-axis hybrid instrument composed of: 70)
- a sphere including three VBB (Very Broad Band) seismic probes and their temperature sensors,
- three SP (Short Period) seismic probes and their temperature sensors,
- an acquisition electronics box (e-box: SEIS AC, SEIS DC/DC, ASICS) and the feedback boards for the VBB, SP probes and the MDE deployment system,
- a deployment system (DPL),
- a software (S/W).
Its mass is about 3 kg.
Its power consumption varies around 1W depending on the modes.
SEIS seismometer main performances are:
• VBB: -9 m s-2 Hz-½ from 10-3 up to 10 Hz
• SP: < 5 x 10-8 m s-2 Hz-½ from 10-2 up to 100 Hz.
Figure 51: A VBB pendulum beside the evacuated sphere that houses it (image credit: IPGP/Sodern/CNES)
Figure 52: The sphere (image credit: CNES)
The sphere harbors the VBB probes (long period seismometers). It is the "noble part" of the instrument. It has House Keeping for the best functioning of the VBB probes.
• It has a thermal screen and torlon plots to reduce the temperature variations of the seismometers as much as possible
• It keeps the probes in vacuum
• It contains temperature sensors (House Keeping - HK) and inclinometers for the exploitation of the data measured by the VBB.
How does it work? -The spring and the pendulum mass are perfectly balanced. When the ground moves, the pendulum begins to move. This movement is registered by the DCS sensor. The balance mechanism can adjust the pendulum balance in real use conditions (poorly known gravity, levelling flaw, influence of the temperature on the pendulum balance). The pivot should enable the rotation of the mobile part around its axis without any friction.
The proximity electronics transforms these characteristics in easily measured tension. It is transmitted to the acquisition electronics. The feedback coil allows the servitude of the pendulum to improve the performances (increase of the bandwidth). The intensity that runs in the coil is delivered by the feedback board "SEIS-FB" located in the e-box. This intensity is generated depending on the measurement of the pendulum displacement.
Figure 53: The VBBs are oblique pendulums. The displacement sensor is constituted of electrodes placed on the fixed and mobile parts. The electrical characteristics thus constituted form an image of the position of the sensor's mobile part (image credit: CNES)
• In May 2017, the flight model sphere, the seismometer’s primary subsystem, has passed its first validation tests. The flight model sphere is the primary subsystem for the SEIS instrument. It was designed by Sodern under the supervision of the Institut de Physique du Globe de Paris (IPGP) and delivered to CNES on 27th April. Tests were performed by Sodern and completed on 30 April 2017. 71)
- Initial tests were successful, and further testing on the fully-assembled instrument were authorised. It was transferred to Intespace facilities in Toulouse for vibration tests, completed on 19th May. All requirements were met, and SEIS will be delivered to Lockheed Martin at the end of July so it can be integrated to the InSight lander.
• August 28, 2017: A bench checkout of InSight's Seismometer Instrument was also conducted in a Lockheed Martin clean room facility in Littleton, Colorado. 72)
Figure 54: The SEIS instrument undergoes a checkout for the spacecraft's ATLO (Assembly, Test and Launch Operations) in this photo taken July 20, 2017, in a Lockheed Martin clean room facility in Littleton, Colorado (image credit: NASA/JPL-Caltech, Lockheed Martin)
HP3 (Heat-Flow and Physical Properties Probe)
HP3 is a heat probe, designed to hammer itself to a depth of 3 to 5 meters and measure the amount of energy coming from the planet's deep interior. The heat probe is supplied by the German Aerospace Center, DLR, with the self-hammering mechanism from Poland. The PI of the HP3 instrument is Tilman Spohn of DLR.
• Heat flow provides InSight into the thermal and chemical evolution of the planet by constraining the concentration of radiogenic elements, the thermal history of the planet and the level of its geologic activity.
• Surface heat flow is measured by determining the regolith thermal conductivity, k, and the thermal gradient dT/dz.
• Measuring the thermal gradient undisturbed by the annual thermal wave
• Accurately measuring the thermal conductivity in an extremely low conductivity environment.
HP3 is a self-penetrating temperature and thermal conductivity probe to determine heat flow. HP3 consists of a so-called “Mole”, which will hammer itself into the subsurface. The mole pulls an instrumented tether behind it, which is equipped with temperature sensors to determine the thermal gradient in the ground. The mole is targeted for a depth of 5 m below the surface. In addition to the temperature sensors, the mole is equipped with heating foils, which will be used to determine the thermal conductivity of the regolith by operating the mole as a modified line heat source. 73) 74) 75) 76)
Figure 55: System assembly overview of the HP3 elements (image credit: DLR)
Figure 56: Photo of the HP3 penetrating mole mechanism (image credit: DLR)
Table 3: Subsystem development of the penetrating mole
Figure 57: Illustration of HP3 mole subsystems developed by the various institutions (image credit: DLR)
Figure 58: Designation of HP3 mole elements (image credit: DLR)
Deep penetration tests were conducted to verify the operation of the instrument.
• Stroke rate: 1 stroke per 4 seconds
• Penetration rate: 5m in ~27 hrs
• Rates primarily determined by available power/voltage from lander.
The instrument package will be placed near the lander, and a self-hammering spike will pound itself as deep as 5 meters into the ground, like a meat thermometer stuck into a turkey. Trailing behind this “spearhead” will be a tether with temperature sensors strung along its length, spaced 10 cm apart.
Variations in temperature measured at different depths underground will show how much and how fast heat is flowing upward through the crust. From these data, the temperature of Mars’ core and the history of its cooling off over time can be estimated.
Mars–like Earth–once had a magnetic field that shielded the planet from the effects of the “solar wind” flowing from the sun. It is now mostly vanished and researchers hope that understanding Mars’ thermal history will reveal what happened.
Earth’s magnetic field shields our planet from the solar wind, and without that protection our atmosphere would experience direct exposure, and slowly be “eroded” away into space.
The HP3 instrument has a mass of ~3 kg, a maximum power consumption of 2 W while burrowing underneath the surface, a total volume of 20 liters and a data volume of ~ 350 Mbit over the course of the mission.
Figure 59: Photo of the development team and the HP3 flight unit which is ready for delivery after extensive tests and reviews (image credit: DLR)
HP3 Operations on the Martian Surface
The operations of HP3 on Mars will start shortly after landing. Instrument checkouts and RAD (Radiometer) scientific measurements will be performed during the early portion of the InSight surface mission, which is dominated by the selection of the instrument deployment sites followed by the deployment of SEIS (Seismometer) and HP3 SSA (Support System Assembly) onto the surface using the lander robotic arm. 77)
The deployment phase will start with a health check of the subsystems STATIL (Static Tiltmeter), TLM (Tether Length Monitor) and TEM (Thermal Excitation and Measurement). The launch locks of the SSA will then be fired by lander commands and the IDS (Instrument Deployment System) will deploy the SSA onto the Martian surface. HP3 will be switched-off during this activity. After positioning of the HP3 SSA onto the Martian surface and before grapple release HP3 will be switched on and the subsystem STATIL will measure the tilt of the deployed SSA. The correct positioning of HP3 will be verified by evaluating camera pictures, models, and the measured inclination data. After HP3 deployment is confirmed, the mole frangibolt is fired, releasing the mole from its launch lock. After releasing the mole, the SSA cannot re-grappled and moved as the risk of uncontrolled mole movement would be too big.
RISE (Rotation and Interior Structure Experiment)
RISE tracks Mars' reflexes as the Sun pushes and pulls it in its orbit. RISE is an X-band Doppler tracking experiment to measure rotational variations of the planet. These observations will provide detailed information Mars' deep inner core. They will help determine on the depth at which Mars' core becomes solid, and which other elements, besides iron, may be present. By measuring the Doppler shift of InSight’s radio transmissions to Earth, precision measurements of Mars’ rotation can be made—in much the same way that the speed of a car can be measured by a police radar gun. Aspects of a planet’s rotation–not just speed of spin, but also cyclic wobbles, the precession and nutation, of its axis–can tell us what’s going on inside, in terms of internal structure.
The RISE instrument has two directional antennas designed with a central axis pointing 28º above the horizon, with one antenna pointing nearly east and the other pointing due west. LaRa (Lander Radioscience) antennas are omnidirectional in azimuth approximately covering the Earth elevation range between 30º and 55º.
The goals of RISE are to deduce the size and density of the martian core through estimation of the precession and nutation of the spin axis. The precession and nutation estimates will be based on measurements of the relative velocity of the InSight lander and tracking stations on Earth. The velocity is related to the Doppler shift of radio signals transmitted from the tracking stations to the lander where they are detected and re-transmitted back to Earth. Doppler measurements are crucially important for navigation of the spacecraft from launch to arrival on Mars. The RISE measurement requirements can be met without any additional equipment but do place constraints on the locations of antennas on the lander. 78)
RISE will use very precise tracking from onboard radio communication devices to look for small variations in planetary rotation. That can give us information about the deep, internal structure of Mars. For example, not much is known right now about the density and size of Mars’s core. The RISE experiment should decrease this uncertainty by a factor of 10 or so. This will help answer questions like why Mars had no magnetic field for most of its history, yet continues to be volcanically active. We will also get a good idea of the thickness of Mars’s crust at the landing site and the current tectonic activity level on Mars, which is impossible to do from orbital observations.
Figure 60: Illustration of possible models for the interiors of Earth, Mars, and the Moon. One model suggests that Mars’ core may have a radius equal to half of the planet’s (image credit: NASA/JPL-Caltech)
Data from the RISE experiment will add to similar measurements made years ago on the Viking and Pathfinder missions, and should give scientists what they need to calculate the size and density of Mars’ core and mantle, furthering our understanding of how rocky planets like Mars and Earth formed.
The RISE instrument consists of two Medium-Gain ‘horn’ Antennas (MGAs) on the lander deck, and an X-band radio transponder and transmitter in the lander's equipment bay, where electronics can be shielded from the harsh, cold conditions of space. The instrument has a total mass of 7.3 kg (2.8 kg for antennas, 4.4 kg for transponder and transmitter), the power consumption is 78 W (operated up to one hour per day), volume of 19.8 liters total.
IDS (Instrument Deployment System)
IDS is a robotic arm to deploy the SEIS and HP3 to the surface, and two cameras to support a variety of operations. IDS is comprised of IDA (Instrument Deployment Arm), an arm-mounted IDC (Instrument Deployment Camera), a lander-mounted ICC (Instrument Context Camera), and control software. IDS is responsible for precision instrument placement on a planetary surface that will enable scientist to perform the first comprehensive surface-based geophysical investigation of Mars. 79)
IDA has 1.9 m reach with four degrees of freedom: yaw (shoulder azimuth) and three pitch joints (shoulder elevation, elbow, and wrist). Each joint has a temperature sensor and heater with a dust seal to prevent contamination of the motor and gearbox. IDC allows visual confirmation of deployment steps, as well as acquisition of the stereo image pairs used to create a 3D map of the workspace. IDC also provides engineering images of solar arrays, payload deck, and instruments. ICC provides context images and redundant worksite imagery.
SNC (Sierra Nevada Corporation) of Sparks, Nevada supplied actuators in the grapple mechanism on the 2.4 m long IDA (Instrument Deployment Arm), which will be used to place the seismometer and heat probe instruments on the Martian surface. The grapple on the robotic arm helps secure each piece of hardware the arm lifts with its five mechanical fingers. The IDA will place a seismometer on the Red Planet’s surface to detect Marsquakes and also will release a probe that digs five meters down into Mars’ interior, deeper than any previous mission. 80)
Figure 61: A view of the mockup arm, end effector, and lander top deck of Insight (left), and a sequence of three graphics representing instrument deployment (right), image credit: NASA/JPL
APSS (Auxiliary Payload Sensor Suite)
APSS is a complement of sensitive environmental sensors to measure wind velocity, atmospheric temperature and pressure, and the magnetic field.
The atmospheric pressure fluctuations on Mars will induce an elastic response in the ground that will create a ground tilt, detectable as a seismic signal on SEIS. This ground tilt due to atmospheric pressure variations is anticipated to be a major seismic signal on the SEIS instrument . It is planned to reduce the atmospheric seismic signal by making use of a pressure sensor that will be part of the InSight APSS (Auxiliary Payload Sensor Suite). Decorrelation techniques will be used to remove the pressure signal from the seismic signal. The pressure sensor will be on the InSight lander and, thus, almost collocated with the seismometer. 81)
APPS will allow the identification of non-seismic signals and the removal of such noise through de-correlation.
- Pressure Sensor – Measures pressure variations from 0.01-1 Hz (10 mPa barometer; JPL)
- TWINS (Temperature and Wind for InSight) – Measures wind speed and direction, air temperature (based on the Curiosity Rover Environmental Monitoring Station (REMS) anemometer and thermal sensors; developed by the Centro de Astrobiologia (CAB), Spain)
- IFG (Insight Flux Gate) – Measures magnetic field variations from DC-10 Hz (0.1 nT vectormagnetometer; UCLA)
- PAE (Payload Auxiliary Electronics) – Control and data acquisition electronics for the APSS sensors.
Figure 62: Location of the instruments/payloads on the InSight Payload deck (image credit: NASA, Ref. 5)
Ground segment - Communications with Earth
NASA's InSight mission uses the NASA's DSN (Deep Space Network), an international network of antennas that provides communication links between planetary exploration spacecraft and their mission teams on Earth. 82)
The Deep Space Network consists of three deep-space communications complexes placed approximately 120 degrees apart around the world: at Goldstone, in California's Mojave Desert; near Madrid, Spain; and near Canberra, Australia. This strategic placement permits constant links to distant spacecraft even as the Earth rotates on its own axis.
As with previous Mars landers and rovers, the InSight mission relies on Mars-orbiting spacecraft to relay data from the spacecraft to the antennas of the Deep Space Network.
Figure 63: Photo of the Goldstone 70 m antenna (image credit: NASA)
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31) ”NASA Engineers Checking InSight's Weather Sensors,” NASA Feature, 24 August 2020, URL: https://www.nasa.gov/feature/jpl/nasa-engineers-checking-insights-weather-sensors
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The information compiled and edited in this article was provided by Herbert J. Kramer from his documentation of: ”Observation of the Earth and Its Environment: Survey of Missions and Sensors” (Springer Verlag) as well as many other sources after the publication of the 4th edition in 2002. - Comments and corrections to this article are always welcome for further updates (email@example.com