Psyche Mission of NASA to the Asteroid Belt
Psyche is both the name of an asteroid orbiting the Sun between Mars and Jupiter — and the name of an ASU (Arizona State University) mission to visit that asteroid. The mission was chosen by NASA on January 4, 2017 as one of two missions for the agency's Discovery Program, a series of low-cost missions to solar system targets. The Psyche spacecraft is targeted to launch in the summer 2022 and travel to the asteroid using solar-electric (low-thrust) propulsion, arriving in 2026, following a Mars flyby and gravity-assist in 2023. After arrival, the mission plan calls for 21 months spent at the asteroid, mapping it and studying its properties. 1)
As NASA looks to explore deeper into our solar system, one of the key areas of interest is studying worlds that can help researchers better understand our solar system and the universe around us. One of the next destinations in this knowledge-gathering campaign is a rare world called Psyche, located in the asteroid belt. 2)
Psyche is different from millions of other asteroids because it appears to have an exposed nickel-iron surface. Researchers at Arizona State University, Tempe, in partnership with NASA's Jet Propulsion Laboratory in Pasadena, California, believe the asteroid could actually be the leftover core of an early planet. And, since we can't directly explore any planet's core, including our own, Psyche offers a rare look into the violent history of our solar system.
"Psyche is a unique body because it is, by far, the largest metal asteroid out there; it's about the size of Massachusetts," said David Oh, the mission's lead project systems engineer at JPL. "By exploring Psyche, we'll learn about the formation of the planets, how planetary cores are formed and, just as important, we'll be exploring a new type of world. We've looked at worlds made of rock, ice and of gas, but we've never had an opportunity to look at a metal world, so this is brand new exploration in the classic style of NASA."
ASU leads the mission. NASA's Jet Propulsion Laboratory in Pasadena, California, is responsible for the mission's overall management, system engineering, integration and test, and mission operations. Maxar Space Solutions, formerly Space Systems Loral, in Palo Alto, California, is providing a high-power solar electric propulsion spacecraft chassis.
Science goals 3)
• Understand a previously unexplored building block of planet formation: iron cores.
• Look inside terrestrial planets, including Earth, by directly examining the interior of a differentiated body, which otherwise could not be seen.
• Explore a new type of world. For the first time, examine a world made not of rock and ice, but metal.
• Determine whether Psyche is a core, or if it is unmelted material.
• Determine the relative ages of regions of Psyche's surface.
• Determine whether small metal bodies incorporate the same light elements as are expected in the Earth's high-pressure core.
• Determine whether Psyche was formed under conditions more oxidizing or more reducing than Earth's core.
• Characterize Psyche's topography.
Figure 1: This artist's concept depicts the 140-mile-wide (226 km wide) asteroid Psyche, which lies in the main asteroid belt between Mars and Jupiter. Psyche is the focal point of NASA's mission of the same name. The Psyche spacecraft is set to launch in August 2022 and arrive at the asteroid in 2026, where it will orbit for 21 months and investigate its composition (image credit: NASA/JPL-Caltech, Peter Rubin) 4)
Figure 2: Artist's concept of the Psyche spacecraft, which will conduct a direct exploration of a metal asteroid Psyche, thought to be a stripped planetary core (image credit: SSL/ASU/P. Rubin/NASA/JPL-Caltech)
But getting to Psyche won't be easy. It requires a cutting-edge propulsion system with exceptional performance, which is also safe, reliable and cost-effective. That's why the mission team has turned to NASA/GRC ( Glenn Research Center) in Cleveland, which has been advancing SEP (Solar Electric Propulsion) for decades.
• October 4, 2021: Set to launch next year, NASA’s Psyche mission marks the first time the agency has set out to explore an asteroid richer in metal than rock or ice. 5)
- More than 150 years have passed since novelist Jules Verne wrote “Journey to the Center of the Earth,” but reality has yet to catch up with that science fiction adventure. While humans can’t bore a path to our planet’s metallic core, NASA has its sights set on visiting a giant asteroid that may be the frozen remains of the molten core of a bygone world.
Figure 3: Engineers at NASA's Jet Propulsion Laboratory in Southern California integrate the gamma ray and neutron spectrometer instrument into the agency's Psyche spacecraft on Aug. 23, 2021 (image credit: NASA/JPL-Caltech)
- Called Psyche, this asteroid orbits the Sun in the main asteroid belt, between Mars and Jupiter. Using data gathered from Earth-based radar and optical telescopes, scientists believe that Psyche is made largely of metal. It could be part or all of the iron-rich interior of an early planetary building block that was stripped of its outer rocky shell as it repeatedly collided with other large bodies during the early formation of the solar system.
- The asteroid, which is about 173 miles (280 km) at its widest point, could also be something else. It could be the leftover piece of a completely different kind of iron-rich body that formed from metal-rich material somewhere in the solar system.
- NASA’s Psyche mission hopes to find out. Set for an August 2022 launch, the spacecraft will for two years orbit the asteroid it was named after, taking pictures, mapping the surface, and looking for evidence of an ancient magnetic field. Psyche also will study the neutrons and gamma rays coming from the asteroid’s surface to help determine its elemental composition.
- The first mission to explore an asteroid with a surface that contains substantial amounts of metal rather than rock or ice, Psyche seeks to better understand iron cores, an unexplored building block of planet formation. The mission also potentially provides the first opportunity to directly examine the inside of a rocky planet by offering a look at the interior of a previously layered planetary body that otherwise could never be seen. What scientists learn could shed additional light on how Earth and other rocky planets formed.
- “There are a lot of basic questions about Psyche that are unanswered,” said the mission’s principal investigator, Lindy Elkins-Tanton of Arizona State University. “And with every detail that gets added from data we can collect from Earth, it just becomes harder to make a sensible story. We really don’t know what we’re going to see until we visit, and we’re going to be surprised.”
- For instance, previous ground-based observations led scientists to believe that the asteroid was as much as 90% metal. Recent research led by Elkins-Tanton used updated density measurements to estimate that the asteroid is more likely between 30% and 60% metal.
- And scientists are puzzled why Psyche appears to be low in iron oxides, which are chemical compounds made of iron and oxygen. Mars, Mercury, Venus, and Earth all have them. “So if we’re correct that Psyche is a mixture of metal and rock, and the rock has very little iron oxide, then there’s got to be a strange story about how it was created – because it doesn’t fit the standard stories of planetary creations,” Elkins-Tanton said.
Mystery of Psyche
- Scientists also don’t know where Psyche formed. It might have originated inside the main asteroid belt, but it’s also possible that it was born in the same zone as the inner planets like Earth – or in outer solar system, where giant planets like Jupiter now reside. Neither origin story follows a simple path to where Psyche lives now, 280 million miles (450 million km) from the Sun.
- Asteroids in general can offer insight into planet formation and how the early solar system worked 4.6 billion years ago. But Psyche is particularly interesting to scientists because of how unusual it is, with its metal content, high density, and low concentration of iron oxides.
- “The fact that it’s so unusual is telling us a new story that we haven’t seen before about how asteroids evolved,” said Bill Bottke, Psyche mission scientist of the Southwest Research Institute in Boulder, Colorado. “That’s a piece of the story we don’t have right now. By getting that piece together with all the others we have, we continue to refine our story of how the solar system formed and evolved early on.”
Tools of the Trade
- To help figure out the asteroid’s origins, the mission’s science investigation will rely on a magnetometer, a gamma ray and neutron spectrometer, and a multispectral imager. Scientists know that the asteroid doesn’t generate a magnetic field the way Earth does, but if Psyche had a magnetic field in the past, it could still be recorded in the asteroid’s material today. With sensors mounted onto a 6-foot (2-meter) boom, the magnetometer can determine whether Psyche is still magnetized. If so, that would confirm that the asteroid is part of the core of an early planetesimal, the building block of an early planet.
- The orbiter’s gamma ray and neutron spectrometer instrument will help scientists determine the asteroid’s chemical elements. As cosmic rays and high-energy particles impact Psyche’s surface, the elements that make up the surface material absorb the energy. The neutrons and gamma rays they emit in response can be detected by the spectrometer, allowing scientists to match their properties to those emitted by known elements to determine what Psyche is made of.
- Meanwhile, a pair of color cameras make up the multispectral imager. The imager is sensitive to light just beyond what humans can see, using filters in the ultraviolet and near-infrared wavelengths. The light reflected in these filters could help determine the mineralogy of any rocky material that may exist on Psyche’s surface.
- The spacecraft’s telecommunications system will help with the science as well. The X-band radio system is primarily used to send commands to the spacecraft and receive engineering and science data from it. But scientists can also analyze subtle changes in these radio waves to measure the body’s rotation, wobble, mass, and gravity field, providing additional clues about the composition and structure of Psyche’s interior.
Figure 4: At NASA's Jet Propulsion Laboratory, an engineer inspects the gamma ray and neutron spectrometer as it is integrated into the agency's Psyche spacecraft. The instrument will help determine the elements that make up its target (image credit: NASA/JPL-Caltech)
Eyes on Psyche
- But before any of this science analysis gets underway, there will be pictures. By late 2025, three years after launch, Psyche will be within sight of the asteroid, and the imager team will be on high alert.
- “Even before we get into orbit, we’ll start getting much better pictures than we can from telescopes on Earth. We’ll start to resolve features, see big craters, crater basins – maybe mountain ranges. Who knows what we’ll see?” said Jim Bell of Arizona State University, deputy principal investigator of Psyche and imager team lead. “All we know is that the reality of Psyche is going to be even weirder and more beautiful than we can imagine.”
• September 20, 2021: When it comes time for NASA’s Psyche spacecraft to power itself through deep space, it’ll be more brain than brawn that does the work. Once the stuff of science fiction, the efficient and quiet power of electric propulsion will provide the force that propels the Psyche spacecraft all the way to the main asteroid belt between Mars and Jupiter. The orbiter’s target: a metal-rich asteroid also called Psyche. 6)
Figure 5: NASA's Psyche spacecraft is photographed in July 2021 during the mission's assembly, test, and launch operations phase at the agency's Jet Propulsion Laboratory in Southern California. The spacecraft will use four Hall thrusters to propel itself to the metal-rich asteroid Psyche, using solar electric propulsion. Two thrusters are visible beneath red round protective covers, after being integrated into the spacecraft. This will be the first use of Hall thrusters beyond lunar orbit, demonstrating that they could play a role in supporting future deep space missions (image credit: NASA/JPL-Caltech)
- The spacecraft will launch in August 2022 and travel about 1.5 billion miles (2.4 billion km) over three and a half years to get to the asteroid, which scientists believe may be part of the core of a planetesimal, the building block of an early rocky planet. Once in orbit, the mission team will use the payload of science instruments to investigate what this unique target can reveal about the formation of rocky planets like Earth.
- The spacecraft will rely on the large chemical rocket engines of the Falcon Heavy launch vehicle to blast off the launchpad and to escape Earth’s gravity. But the rest of the journey, once Psyche separates from the launch vehicle, will rely on solar electric propulsion. This form of propulsion starts with large solar arrays that convert sunlight into electricity, providing the power source for the spacecraft’s thrusters. They’re known as Hall thrusters, and the Psyche spacecraft will be the first to use them beyond the orbit of our Moon.
Figure 6: At left, xenon plasma emits a blue glow from an electric Hall thruster identical to those that will propel NASA's Psyche spacecraft to the main asteroid belt. On the right is a similar non-operating thruster (image credit: NASA/JPL-Caltech)
- For propellant, Psyche will carry tanks full of xenon, the same neutral gas used in car headlights and plasma TVs. The spacecraft’s four thrusters will use electromagnetic fields to accelerate and expel charged atoms, or ions, of that xenon. As those ions are expelled, they create thrust that gently propels Psyche through space, emitting blue beams of ionized xenon.
- In fact, the thrust is so gentle, it exerts about the same amount of pressure you’d feel holding three quarters in your hand. But it’s enough to accelerate Psyche through deep space. With no atmospheric drag to hold it back, the spacecraft eventually will accelerate to speeds of up to 200,000 miles/hour (320,000 km/hour).
- Because they’re so efficient, Psyche’s Hall thrusters could operate nearly nonstop for years without running out of fuel. Psyche will carry 922 kg of xenon in its tanks; engineers estimate that the mission would burn through about five times that amount of propellant if it had to use traditional chemical thrusters.
- “Even in the beginning, when we were first designing the mission in 2012, we were talking about solar electric propulsion as part of the plan. Without it, we wouldn’t have the Psyche mission,” said Arizona State University’s Lindy Elkins-Tanton, who as principal investigator leads the mission. “And it’s become part of the character of the mission. It takes a specialized team to calculate trajectories and orbits using solar electric propulsion.”
Figure 7: Engineers at NASA/JPL, prepare to integrate four Hall thrusters (beneath red protective covers) into the agency's Psyche spacecraft in July 2021 (image credit: NASA/JPL-Caltech)
• August 24, 2021: As part of NASA’s Discovery Program, the mission to explore a metal-rich asteroid is well on its way to an August 2022 launch. 7)
Figure 8: NASA's Psyche spacecraft is in the midst of system integration and test at JPL. This image was taken on August 18, 2021, less than a year from launch in August 2022 (image credit: NASA/JPL-Caltech)
- With NASA’s Psyche mission now less than a year from launch, anticipation is building. By next spring, the fully assembled spacecraft will ship from the agency’s Jet Propulsion Laboratory in Southern California to NASA’s Kennedy Space Center in Florida for a launch period that opens Aug. 1, 2022.
- In early 2026, the Psyche spacecraft will arrive at its target, an asteroid of the same name in the main asteroid belt between Mars and Jupiter. Scientists believe asteroid Psyche, which is about 226 km wide, is made largely of iron and nickel and could be the core of an early planet.
- The spacecraft will spend 21 months orbiting the asteroid and gathering science data with a magnetometer, a multispectral imager, and a gamma ray and neutron spectrometer. The information the instruments gather won’t just help scientists understand this particular object; it will lend valuable insight into how Earth and other planets formed.
- “It’s incredible to be at this point now, with a big spacecraft coming together and one year until launch,” said Arizona State University’s Lindy Elkins-Tanton, who as principal investigator leads the Psyche mission. “Like everyone in the world, our team has faced many challenges of the COVID pandemic, and we are putting in maximum effort to make it to the finish line. I’m so proud of this incredible group of people!”
- In March, Maxar Technologies delivered to JPL the spacecraft’s Solar Electric Propulsion Chassis, with most of the engineering hardware needed for the electrical system, the propulsion systems, the thermal system, and the guidance and navigation system. Psyche will use Maxar’s superefficient electric propulsion system to travel through deep space. The spacecraft’s delivery coincided with the kickoff of the mission phase known as assembly, test, and launch operations.
- The mission also will test a sophisticated new laser communications technology, recently completed by JPL, called Deep Space Optical Communications (DSOC). The technology demonstration will focus on using lasers to enhance communications speeds and prepare for data-intensive transmissions, which could potentially include livestream videos for future missions.
- Engineers already have completed the successful integration of the magnetometer and DSOC with the Psyche spacecraft. The Psyche spectrometer will be integrated over the next few months, along with the imager.
- When the spacecraft is fully assembled, it will move into JPL’s huge thermal vacuum chamber for testing that simulates the environment of deep space. The entire spacecraft then will be attached to a large shaker table in an acoustic chamber to simulate the environment of launch.
- “We have all been watching the spacecraft come together on the floor of the clean room. It’s tremendously exciting after all the years of hard work designing the system, and building and testing its myriad of components,” said JPL’s Henry Stone, the Psyche project manager. “The pressure is now on to complete assembly and test of the vehicle prior to shipment to Cape Canaveral in less than a year. It’s both exhilarating and stressful for all involved, but I have total confidence in this team’s ability to get the job done in time for our launch. Go, Psyche!”
• August 5, 2021: A close examination of the millimeter-wavelength emissions from the asteroid Psyche, which NASA intends to visit in 2026, has produced the first temperature map of the object, providing new insight into its surface properties. The findings, described in a paper published in Planetary Science Journal (PSJ) on August 5, are a step toward resolving the mystery of the origin of this unusual object, which has been thought by some to be a chunk of the core of an ill-fated protoplanet. 8)
- Psyche orbits the sun in the asteroid belt, a donut-shaped region of space between Earth and Jupiter that contains more than a million rocky bodies that range in size from 10 meters to 946 km in diameter.
- With a diameter of more than 200 km, Psyche is the largest of the M-Type asteroids, an enigmatic class of asteroids that are thought to be metal rich and therefore potentially may be fragments of the cores of proto-planets that broke up as the solar system formed.
- "The early solar system was a violent place, as planetary bodies coalesced and then collided with one another while settling into orbits around the sun," says Caltech's Katherine de Kleer, assistant professor of planetary science and astronomy and lead author of the PSJ article. "We think that fragments of the cores, mantles, and crusts of these objects remain today in the form of asteroids. If that's true, it gives us our only real opportunity to directly study the cores of planet-like objects." 9)
- Studying such relatively tiny objects that are so far away from Earth (Psyche drifts at a distance that ranges between 179.5 and 329 million km from Earth) poses a significant challenge to planetary scientists, which is why NASA plans to send a probe to Psyche to examine it up close. Typically, thermal observations from Earth—which measure the light emitted by an object itself rather than light from the sun reflected off of that object—are in infrared wavelengths and can produce only 1-pixel images of asteroids. That one pixel does, however, reveal a lot of information; for example, it can be used to study the asteroid's thermal inertia, or how fast it heats up in sunlight and cools down in darkness.
- "Low thermal inertia is typically associated with layers of dust, while high thermal inertia may indicate rocks on the surface," says Caltech's Saverio Cambioni, postdoctoral scholar in planetary science and co-author of the PSJ article. "However, discerning one type of landscape from the other is difficult." Data from viewing each surface location at many times of day provide much more detail, leading to an interpretation that is subject to less ambiguity, and which provide a more reliable prediction of landscape type prior to a spacecraft's arrival.
- De Kleer and Cambioni, together with co-author Michael Shepard of Bloomsburg University in Pennsylvania, took advantage of the Atacama Large Millimeter/submillimeter Array (ALMA) in Chile, which became fully operational in 2013, to obtain such data. The array of 66 radio telescopes enabled the team to map the thermal emissions from Psyche's entire surface at a resolution of 30 km (where each pixel is 30 km by 30 km) and generate an image of the asteroid composed of about 50 pixels.
Figure 9: Millimeter-wavelength emissions reveal the temperature of the asteroid Psyche as it rotates through space (image credit: NASA/JPL-Caltech)
- This was possible because ALMA observed Psyche at millimeter wavelengths, which are longer (ranging from 1 to 10 mm) than the infrared wavelengths (typically between 5 and 30 µm). The use of longer wavelengths allowed the researchers to combine the data collected from the 66 telescopes to create a much larger effective telescope; the larger a telescope, the higher the resolution of the images it produces.
- The study confirmed that Psyche's thermal inertia is high compared to that of a typical asteroid, indicating that Psyche has an unusually dense or conductive surface. When de Kleer, Cambioni, and Shepard analyzed the data, they also found that Psyche's thermal emission—the amount of heat it radiates—is just 60 percent of what would be expected from a typical surface with that thermal inertia. Because surface emission is affected by the presence of metal on the surface, their finding indicates that Psyche's surface is no less than 30 percent metal. An analysis of the polarization of the emission helped the researchers to roughly determine what form that metal takes. A smooth solid surface emits well-organized polarized light; the light emitted by Psyche, however, was scattered, suggesting that rocks on the surface are peppered with metallic grains.
- "We've known for many years that objects in this class are not, in fact, solid metal, but what they are and how they formed is still an enigma," de Kleer says. The findings reinforce alternative proposals for Psyche's surface composition, including that Psyche could be a primitive asteroid that formed closer to the sun than it is today instead of a core of a fragmented protoplanet.
- The techniques described in this study provide a new perspective on asteroid surface compositions. The team is now expanding its scope to apply these techniques to other large objects in the asteroid belt.
- The study was enabled by a related project by the team led by Michael Shepard at Bloomsburg University that utilized de Kleer's data in combination with data from other telescopes, including Arecibo Observatory in Puerto Rico, to pin down the size, shape, and orientation of Psyche. That in turn allowed the researchers to determine which pixels that had been captured actually represented the asteroid's surface. Shepard's team was scheduled to observe Psyche again at the end of 2020, but damage from cable failures shut the telescope down before the observations could be made.
• March 29, 2021: Set to launch next year, the agency’s Psyche spacecraft will explore a metal-rich asteroid in the main asteroid belt between Mars and Jupiter. 10)
Figure 10: A major component of NASA's Psyche spacecraft has been delivered to the agency's Jet Propulsion Laboratory in Southern California, where the phase known as assembly, test, and launch operations (ATLO) is now underway. Taken on March 28, 2021, this photo shows the Solar Electric Propulsion (SEP) Chassis just after it was delivered to JPL by Maxar Technologies. Here, the chassis is about to be attached to the dolly in High Bay 1 of JPL's Spacecraft Assembly Facility (image credit: NASA/JPL-Caltech)
- The SEP (Solar Electric Propulsion) Chassis, crafted by Maxar Technologies’ team in Palo Alto, California, is the size of a van and represents more than 80% (by mass) of the hardware that will ultimately make up the Psyche spacecraft. The large, box-shaped structure made a dramatic entrance as it rolled into the white-walled clean room of JPL’s storied High Bay 1 of the Spacecraft Assembly Facility. Some of the chassis’ most visible features include the 6.5-foot-wide (2-meter-wide) high-gain antenna, the frame that will hold the science instruments, and bright red protective covers to safeguard delicate hardware.
- “Seeing this big spacecraft chassis arrive at JPL from Maxar is among the most thrilling of the milestones we’ve experienced on what has already been a 10-year journey,” said Arizona State University’s Lindy Elkins-Tanton, who as principal investigator leads the Psyche mission. “Building this complex, precision piece of engineering during the year of COVID is absolutely a triumph of human determination and excellence.”
- Over the next 12 months, the project team will be working against the clock to meet deadlines in the runup to launch.
- “It’s exciting watching it all come together, and it’s the part of the project life cycle that I love the most,” said Psyche Project Manager Henry Stone of JPL. “But it’s a really intense phase as well. It’s intricate choreography, and if one activity runs into a problem, it can impact the whole process. Staying on schedule at this phase of the mission is absolutely critical.”
- The SEP Chassis comes to JPL with most of the engineering hardware systems already integrated. The Maxar team built the entire structure and integrated the hardware needed for the high-power electrical system, the propulsion systems, the thermal system, and the guidance and navigation system. The Psyche mission will take advantage of Maxar’s superefficient electric propulsion system to push Psyche through deep space. Maxar will also deliver the large, twin five-panel solar arrays that provide the power for the spacecraft systems.
- “Delivering the SEP Chassis to NASA’s JPL is an incredible accomplishment for us at Maxar,” said Steven Scott, Maxar’s Psyche program manager. “I am so proud of our team. We’ve managed to design and build an SEP spacecraft for a billion-mile journey through a low-power environment, all while prioritizing the health and safety of our team during a global pandemic. The collaboration between Maxar, Arizona State University, and NASA’s JPL is a model for success, and we’re honored to be part of the Psyche Mission."
Building and Testing
- The assembly, test, and launch operations phase kicked off March 16, when engineers gathered in High Bay 1 to begin checking out the JPL-supplied subsystems, the flight computer, the communications system, and the low-power distribution system to be sure they work together. Now that the chassis has arrived, JPL and Maxar engineers will begin installing the remaining hardware, testing as they go.
- The mission’s three science instruments will arrive at JPL over the next few months. The magnetometer will investigate the asteroid’s potential magnetic field. The multispectral imager will capture images of its surface. And the spectrometer will analyze the neutrons and gamma rays coming from the surface to determine the elements that make up the asteroid. JPL is also providing a technology demonstration instrument that will test high data-rate laser communications that could be used by future NASA missions.
Figure 11: Arrival of the SEP component of NASA's Psyche spacecraft at JPL. Over the next year, the spacecraft will finish assembly and undergo rigorous checkout and testing before it’s shipped to Cape Canaveral, Florida, for an August 2022 launch to the main asteroid belt (video credit: NASA-JPL/Caltech)
- Once the full spacecraft is assembled, the orbiter will move from the Spacecraft Assembly Facility to JPL’s large thermal vacuum chamber – a massive undertaking in itself – to simulate the harsh environment of deep space. The chamber is where JPL engineers will begin the heavy-duty testing to ensure the entire machine can survive deep space, thrust with the electric propulsion system, take science measurements, and communicate with Earth.
- By next spring, the fully assembled Psyche will be shipped to NASA’s Kennedy Space Center in advance of its August 2022 target launch date. The spacecraft will fly by Mars for a gravity assist in May 2023 and in early 2026, will go into orbit around the asteroid, where it will spend 21 months gathering science data.
• February 2, 2021: Now just a year and a half from launch, the mission to explore a metal-rich asteroid will soon begin assembling and testing the spacecraft. 11)
- NASA’s Psyche mission has passed a critical milestone that moves it a step closer to launch. After an intense review of the mission’s progress in building its science instruments and engineering systems, Psyche won clearance to progress into what NASA calls Phase D of its life cycle – the final phase of operations prior to its scheduled launch in August 2022.
Figure 12: Technicians power on the main body of NASA's Psyche spacecraft, called the SEP (Solar Electric Propulsion) Chassis, at Maxar Technologies in Palo Alto, CA, in November 20202 (image credit: Maxar Technologies)
- Until now, the mission has focused on planning, designing, and building the body of the spacecraft, its solar-electric propulsion system, the three science instruments, electronics, the power subsystem, and the like. The successful review of those elements means the mission can now begin delivering components to NASA’s Jet Propulsion Laboratory, which manages the mission and will test, assemble, and integrate each piece.
- “It’s really the final phase, when all of the puzzle pieces are coming together and we’re getting on the rocket. This is the most intense part of everything that happens on the ground,” said Arizona State University’s Lindy Elkins-Tanton, who as principal investigator for Psyche leads the mission.
- Psyche’s target is an intriguing, metal-rich asteroid of the same name, which orbits the Sun in the main asteroid belt between Mars and Jupiter. Scientists think that, unlike rocky or icy asteroids, Psyche is largely iron and nickel and could be the heart of an early planet that lost its outer layers. Exploring the asteroid Psyche (about 140 miles, or 226 kilometers, wide) could lend valuable insight into how Earth and other planets formed.
- The Psyche spacecraft will use a magnetometer to detect a potential magnetic field; if the asteroid has one, it’s a strong indicator that it once was the core of an early planet. A multispectral imager will capture images of the surface, as well as gather information about the asteroid’s composition and topography. Spectrometers will analyze the neutrons and gamma rays coming from the surface to reveal the elements that make up the object.
- The main structure of the spacecraft, called the Solar Electric Propulsion (SEP) Chassis, was designed and built by Maxar Technologies and is nearly complete. The Maxar team in Palo Alto, California, is preparing to ship it to JPL’s main clean room in March, when assembly, test, and launch operations begin.
- Each instrument will then undergo further testing. That includes a laser technology demonstration called Deep Space Optical Communications, led by JPL, which uses a super-efficient method of transmitting data with photons, or fundamental particles of visible light. Also undergoing testing will be the thermal, telecommunications, propulsion, power, avionics, and other engineering subsystems, along with the flight computer.
- “The project has made tremendous progress, particularly given the world around us and COVID-19 and dealing with the constraints that imposes,” said JPL’s Henry Stone, the Psyche project manager. “We’re in very good shape. We’re on track and have a plan to go forward to make launch.”
- Although engineers and technicians have had to deal with shutdowns forced by the pandemic and to adhere to additional safety protocols for those doing hands-on work on the spacecraft, the project remains on schedule.
- “The fact that we can still make this happen and we’re overcoming our challenges feels near-miraculous,” Elkins-Tanton said. “And it’s also an incredible gift to keep us all focused and moving forward in a difficult time. So reaching this milestone has special meaning – not just for this project that we’ve been working on for a decade, but also because of what’s been happening more recently in all of our lives.”
- By spring of 2022, the spacecraft will be fully assembled and ready to ship to NASA’s Kennedy Space Center in Cape Canaveral, Florida, where it will launch in August 2022. Psyche will fly by Mars for a gravity assist in May 2023. And in early 2026, it will slip into orbit around the asteroid, where it will spend 21 months gathering data for analysis.
• October 26, 2020: A new study authored by SwRI ( Southwest Research Institute) planetary scientist Dr. Tracy Becker discusses several new views of the asteroid 16 Psyche, including the first ultraviolet observations. The study, which was published today in The Planetary Science Journal and presented at the virtual meeting of the American Astronomical Society’s Division for Planetary Sciences, paints a clearer view of the asteroid than was previously available. 12) 13)
- At about 140 miles in diameter, Psyche is one of the most massive objects in the main asteroid belt orbiting between Mars and Jupiter. Previous observations indicate that Psyche is a dense, largely metallic object thought to be the leftover core of a planet that failed in formation.
- “We’ve seen meteorites that are mostly metal, but Psyche could be unique in that it might be an asteroid that is totally made of iron and nickel,” Becker said. “Earth has a metal core, a mantle and crust. It’s possible that as a Psyche protoplanet was forming, it was struck by another object in our solar system and lost its mantle and crust.”
- Becker observed the asteroid at two specific points in its rotation to view both sides of Psyche completely and delineate as much as possible from observing the surface at ultraviolet (UV) wavelengths.
- “We were able to identify for the first time on any asteroid what we think are iron oxide ultraviolet absorption bands,” she said. “This is an indication that oxidation is happening on the asteroid, which could be a result of the solar wind hitting the surface.”
- Becker’s study comes as NASA is preparing to launch the spacecraft Psyche, which will travel to the asteroid as part of an effort to understand the origin of planetary cores. The mission is set to launch in 2022. Metal asteroids are relatively rare in the solar system, and scientists believe Psyche could offer a unique opportunity to see inside a planet.
- “What makes Psyche and the other asteroids so interesting is that they’re considered to be the building blocks of the solar system,” Becker said. “To understand what really makes up a planet and to potentially see the inside of a planet is fascinating. Once we get to Psyche, we’re really going to understand if that’s the case, even if it doesn’t turn out as we expect. Any time there’s a surprise, it’s always exciting.”
- Becker also observed that the asteroid’s surface could be mostly iron, but she noted that the presence of even a small amount of iron could dominate UV observations. However, while observing Psyche, the asteroid appeared increasingly reflective at deeper UV wavelengths.
- “This is something that we need to study further,” she said. “This could be indicative of it being exposed in space for so long. This type of UV brightening is often attributed to space weathering.”
• July 7, 2020: Psyche, the NASA mission to explore a metal-rock asteroid of the same name, recently passed a crucial milestone that brings it closer to its August 2022 launch date. Now the mission is moving from planning and designing to high-gear manufacturing of the spacecraft hardware that will fly to its target in the main asteroid belt between Mars and Jupiter. 14)
- Like all NASA missions, early work on Psyche started with drawing up digital blueprints. Then came the building of engineering models, which were tested and retested to confirm that the systems would do their job in deep space - by operating the spacecraft, taking science data and communicating it back to Earth.
- And the team just sailed through a key stage in that process, the CDR (Critical Design Review). That's when NASA examines the designs for all of the project systems, including the three science instruments and all of the spacecraft engineering subsystems, from telecommunications, propulsion, and power to avionics and the flight computer.
- "It's one of the most intense reviews a mission goes through in its entire life cycle," said Lindy Elkins-Tanton, who as principal investigator for Psyche leads the overall mission. "And we passed with flying colors. The challenges are not over, and we're not at the finish line, but we're running strong."
Studying a Metal-Rock World
- Mission scientists and engineers worked together to plan the investigations that will determine what makes up the asteroid Psyche, one of the most intriguing targets in the main asteroid belt. Scientists think that, unlike most other asteroids that are rocky or icy bodies, Psyche is largely metallic iron and nickel - similar to Earth's core - and could be the heart of an early planet that lost its outer layers.
- Since we can't examine Earth's core up-close, exploring the asteroid Psyche (about 140 miles, or 226 km, wide) could give valuable insight into how our own planet and others formed.
- To that end, the Psyche spacecraft will use a magnetometer to measure the asteroid's magnetic field. A multispectral imager will capture images of the surface, as well as data about the composition and topography. Spectrometers will analyze the neutrons and gamma rays coming from the surface to reveal the elements that make up the asteroid itself.
- The mission team made prototypes and engineering models of the science instruments and many of the spacecraft's engineering subsystems. These models are manufactured with less expensive materials than those that will fly on the mission; that way they can be thoroughly tested before actual flight hardware is built.
- "This is planning on steroids" said Elkins-Tanton, who also is managing director and co-chair of the Interplanetary Initiative at Arizona State University in Tempe. "And it includes trying to understand down to seven or eight levels of detail exactly how everything on the spacecraft has to work together to ensure we can measure our science, gather our data and send all the data back to Earth. The complexity is mind-boggling."
Figure 13: An electric Hall thruster, identical to those that will be used to propel NASA's Psyche spacecraft, undergoes testing at NASA's Jet Propulsion Laboratory. The blue glow is produced by the xenon propellant, a neutral gas used in car headlights and plasma TVs (image credit: NASA/JPL-Caltech)
• June 11, 2019: Designed to explore a metal asteroid that could be the heart of a planet, the Psyche mission is readying for a 2022 launch. After extensive review, NASA Headquarters in Washington has approved the mission to begin the final design and fabrication phase, otherwise known as Phase C. This is when the Psyche team finalizes the system design, develops detailed plans and procedures for the spacecraft and science mission, and completes both assembly and testing of the spacecraft and its subsystems. 15)
- "The Psyche team is not only elated that we have the go-ahead for Phase C, more importantly we are ready," said Principal Investigator Lindy Elkins-Tanton of Arizona State University in Tempe. "With the transition into this new mission phase, we are one big step closer to uncovering the secrets of Psyche, a giant mysterious metallic asteroid, and that means the world to us."
- The mission still has three more phases to clear. Phase D, which will begin sometime in early 2021, includes final spacecraft assembly and testing, along with the August 2022 launch. Phase E, which begins soon after Psyche hits the vacuum of space, covers the mission's deep-space operations and science collection. Finally, Phase F occurs after the mission has completed its science operations; it includes both decommissioning the spacecraft and archiving engineering and science data.
- Asteroid Psyche is one of the most intriguing targets in the main asteroid belt. While most asteroids are rocky or icy bodies, scientists think Psyche is composed mostly of iron and nickel, similar to Earth's core. They wonder whether Psyche could be the nickel-iron heart, or exposed core, of an early planet maybe as large as Mars that lost its rocky outer layers through violent collisions billions of years ago. If so, it would provide a unique look into the solar system's distant past, when the kind of high-speed protoplanet encounters that created Earth and the other terrestrial planets were common.
- The Psyche mission aims to understand the building blocks of planet formation by exploring firsthand a wholly new and uncharted type of world. Along with determining whether Psyche is the core of an early planet, the team wants to determine how old it is, whether it formed in similar ways to Earth's core and what its surface is like.
Building the Spacecraft (Ref. 14): Now that Psyche is full-speed ahead on building hardware, there's no time to lose. Assembly and testing of the full spacecraft begins in February 2021, and every instrument - including a laser technology demonstration called DSOC (Deep Space Optical Communications), led by NASA's Jet Propulsion Laboratory - has a deadline of April 2021 to be delivered to JPL's main clean room.
Maxar Technologies in Palo Alto, California, is building the main body of the spacecraft, called the Solar Electric Propulsion (SEP) Chassis. Maxar also will deliver the five-panel solar arrays, shown here, that will provide the power for the spacecraft systems.
Figure 14: This artist's concept, updated as of June 2020, depicts NASA's Psyche spacecraft. Set to launch in August 2022, the Psyche mission will explore a metal-rich asteroid of the same name that lies in the main asteroid belt between Mars and Jupiter. The spacecraft will arrive in early 2026 and orbit the asteroid for nearly two years to investigate its composition (image credit: NASA/JPL-Caltech, Peter Rubin)
The main body of the spacecraft, called the SEP Chassis, is already being built at Maxar Technologies in Palo Alto, California. While observing social-distancing requirements for COVID-19 prevention, engineers there are working to attach the propulsion tanks. In February 2021, Maxar will deliver the SEP Chassis to JPL in Southern California and then deliver the solar arrays that provide all of the power for the spacecraft systems a few months later.
Meanwhile, Psyche work is also buzzing at JPL, which manages the mission. Engineers who are essential to perform hands-on work are building and testing electronic components while following COVID-19 safety requirements. The rest of the JPL team is working remotely.
JPL provides the avionics subsystem, which includes Psyche's flight computer - the brain of the spacecraft. With equipment spread out on racks in a clean room, engineers test each piece before integrating it with the next. Once everything is connected, they test the full system with the software, operating the electronics exactly as they will be used in flight.
"One of the things we pride ourselves on in these deep-space missions is the reliability of the hardware," said Psyche Project Manager Henry Stone of JPL. "The integrated system is so sophisticated that comprehensive testing is critical. You do robustness tests, stress tests, as much testing as you can - over and above.
Next up for Psyche: that February 2021 deadline to start ATLO (Assembly, Test and Launch Operations).
DSOC (Deep Space Optical Communication): The Psyche mission will test a sophisticated new laser communication technology that encodes data in photons (rather than radio waves) to communicate between a probe in deep space and Earth. Using light instead of radio allows the spacecraft to communicate more data in a given amount of time. The DSOC team is based at the Jet Propulsion Laboratory.
The Psyche mission will use the X-band radio telecommunications system to measure Psyche’s gravity field to high precision. When combined with topography derived from onboard imagery, this will provide information on the interior structure of Psyche. The team is based at Massachusetts Institute of Technology and the Jet Propulsion Laboratory.
Figure 15: The Psyche mission will test a sophisticated new laser communication technology that encodes data in photons (rather than radio waves) to communicate between a probe in deep space and Earth. Using light instead of radio allows the spacecraft to communicate more data in a given amount of time. The DSOC team is based at the Jet Propulsion Laboratory (image credit: ASU)
The Psyche spacecraft has a mass of ~2800 kg (dry mass of ~1650 kg), a payload mass of 30kg and a power generation of 4.5 kW. The cruise phase is 3.5 years, the planned science mission is 21 months. The solar array performance is 20 kW in Earth orbit and diminishes to 2.3 kW at Psyche.
This mission will use the model SPT-140 (Stationary Plasma Thruster-140) engine, a Hall-effect thruster utilizing solar electric propulsion, where electricity generated from solar panels is transmitted to an electric, rather than chemically powered, rocket engine. The thruster is nominally rated at 4.5 kW operating power, but it will also operate for long durations at about 900 W. Psyche will be the first mission to use Hall-effect thrusters beyond lunar orbit.
Launch: The launch of the Psyche mission is planned for July-August 2022 on a Falcon Heavy vehicle from Launch Complex 39A at the Kennedy Space Center. Psyche will be launched on a trajectory that will perform a gravity assist maneuver past Mars in May 2023, toward the asteroid belt, and intercept the asteroid Psyche. Arrival of Psyche at the asteroid in 2026. 16)
Figure 16: Trajectory of the Psyche satellite mission (image credit: ASU) 17)
Sensor complement (MSI, GRNS, Magnetometer)
The spacecraft's instrument payload includes three science instruments. The mission's magnetometer is designed to detect and measure the remnant magnetic field of the asteroid. The multispectral imager will provide high-resolution images using filters to discriminate between Psyche's metallic and silicate constituents. Its gamma ray and neutron spectrometer will detect, measure and map Psyche's elemental composition. The mission also will test a sophisticated new laser communications technology, called Deep Space Optical Communications. 18)
MSI (Multispectral Imager)
The MSI provides high-resolution images using filters to discriminate between Psyche’s metallic and silicate constituents. The instrument consists of a pair of identical cameras designed to acquire geologic, compositional, and topographic data. The purpose of the second camera is to provide redundancy for mission-critical optical navigation. The team is based at Arizona State University.
The MSI will provide high-resolution images using filters to discriminate between metallic and silicate constituents.
GRNS (Gamma Ray and Neutron Spectrometer)
The GRNS will detect, measure, and map Psyche’s elemental composition. The instrument is mounted on a 6-foot (2-meter) boom to distance the sensors from background radiation created by energetic particles interacting with the spacecraft and to provide an unobstructed field of view. The team is based at the Applied Physics Laboratory at Johns Hopkins University.
Figure 17: Meet the team designing and building the Psyche mission’s gamma ray and neutron spectrometer. This instrument on the spacecraft will detect, measure, and map Psyche’s elemental composition. It is mounted on a 6-foot (2-meter) boom to distance the sensors from background radiation created by energetic particles interacting with the spacecraft and to provide an unobstructed field of view. The team is based at the Applied Physics Laboratory at Johns Hopkins University and is led by Principal Investigator David Lawrence (video credit: JHU/APL, ASU)
The Psyche Magnetometer is designed to detect and measure the remnant magnetic field of the asteroid. It is composed of two identical high-sensitivity magnetic field sensors located at the middle and outer end of a 6-foot (2-meter) boom. The team is based at Massachusetts Institute of Technology and Technical University of Denmark (DTU).
2) ”NASA Glenn Tests Thruster Bound for Metal World,” NASA/JPL, Sept. 28, 2017, URL: https://www.jpl.nasa.gov/news/news.php?release=2017-253
3) ”Psyche Overview,” NASA, 5 May 2020, URL: https://www.nasa.gov/mission_pages/psyche/overview/index.html
4) ”A Metal-Rich World (Artist's Concept),” NASA/JPL, 7 July 2020, URL: https://www.jpl.nasa.gov/spaceimages/details.php?id=PIA23876
5) ”Science of Psyche: Unique Asteroid Holds Clues to Early Solar System,” NASA/JPL, 04 October 2021, URL: https://www.jpl.nasa.gov/news/science-of-psyche-unique-asteroid-holds-clues-to-early-solar-system?utm_source=iContact&utm_medium=email&utm_campaign=nasajpl&utm_content=daily20211004-1
6) ”Solar Electric Propulsion Makes NASA’s Psyche Spacecraft Go,” NASA/JPL, 20 September 20 2021, URL:
7) ”One Year Out: NASA’s Psyche Mission Moves Closer to Launch,” NASA/JPL News, 24 August 2021, URL: https://www.jpl.nasa.gov/news/one-year-out-nasas-psyche-mission-moves-closer-to-launch?
Robert Perkins, ”Observatory in Chile Takes Highest-Resolution
Measurements of Asteroid Surface Temperatures Ever Obtained from
Earth,” Caltech News, 5 August 2021, URL: https://www.caltech.edu/about/news/observatory-in-chile-takes-highest-resolution-
9) Katherine de Kleer, Saverio Cambioni and Michael Shepard, ”The Surface of (16) Psyche from Thermal Emission and Polarization Mapping,” The Planetary Science Journal, Volume 2, Number 4, Published: 5 August 2021, https://doi.org/10.3847/PSJ/ac01ec, URL: https://iopscience.iop.org/article/10.3847/PSJ/ac01ec/pdf
10) ”NASA Begins Final Assembly of Spacecraft Destined for Asteroid Psyche,” NASA/JPL, 29 March, 2021, URL: https://www.jpl.nasa.gov/news/
11) ”NASA’s Psyche Mission Moves Forward, Passing Key Milestone,” NASA/JPL, 2 February 2021, URL: https://www.jpl.nasa.gov/news/nasas-psyche-mission-moves-forward-passing-key-milestone?
12) ”SwRI study offers more complete view of massive asteroid Psyche,” SwRI Press Release, 26 October 2020, URL: https://www.swri.org/press-release/
13) Tracy M. Becker, Nathaniel Cunningham, Philippa Molyneux, Lorenz Roth, Lori M. Feaga, Kurt D. Retherford, Zoe A. Landsman, Emma Peavler, Linda T. Elkins-Tanton and Jan-Erik Walhund, ”HST UV Observations of Asteroid (16) Psyche,” The Planetary Science Journal, Volume 1, Number 3, Published: 26 October 2020, https://doi.org/10.3847/PSJ/abb67e, URL: https://iopscience.iop.org/article/10.3847/PSJ/abb67e/pdf
14) ”Building NASA's Psyche: Design Done, Now Full Speed Ahead on Hardware,” NASA/JPL News, 7 July 2020, URL: https://www.jpl.nasa.gov/news/news.php?release=2020-125
15) ”NASA's Psyche Mission Has a Metal World in Its Sights,” NASA/JPL, Caltech, 11 June 2019, URL: https://www.jpl.nasa.gov/news/news.php?feature=7419&utm_source=iContact&
16) Jeff Foust, ”Falcon Heavy to launch NASA Psyche asteroid mission,” SpaceNews, 28 February 2020, URL: https://spacenews.com/falcon-heavy-to-launch-nasa-psyche-asteroid-mission/
18) ”Instruments & Science Investigations,” ASU, 18 June 2020, URL: https://psyche.asu.edu/mission/instruments-science-investigations/
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).