SCaN (Space Communications and Navigation) — the 'ground' infrastructure of NASA
Space Communications and Navigation (SCaN) serves as the Program Office for all of NASA's space communications activities. SCaN manages and directs the ground-based facilities and services provided by the Deep Space Network (DSN), Near Earth Network (NEN) and Space Network (SN), and the SN's space segment, the Tracking and Data Relay Satellites (TDRS).
Space Communications and Navigation: Exploration Enabled, Then and Now 1)
Fifty years ago, NASA captured the world's imagination and inspired generations with the Apollo 11 Moon landing. Back then, NASA's communications networks were crucial to mission success. Today, they provide critical service as America moves forward to the Moon in 2024.
NASA's SCaN (Space Communications and Navigation) Program manages and directs the three prime NASA space communications networks, namely DSN (Deep Space Network), NEN (Near Earth Network) and SN (Space Network), into a global communications infrastructure for space exploration. SCAN was established in 2006, it was previously known as the Space Communications & Data Systems (SCDS) Program.
The agency's new lunar exploration program is called Artemis. NASA's SLS (Space Launch System) rocket will send astronauts aboard the Orion spacecraft to the Gateway in lunar orbit. Crew will take expeditions to the surface of the Moon in a human landing system, go back to the Gateway and return to Earth aboard Orion.
SCaN will support Artemis missions each step of the way. We're modernizing technologies like optical communications to ensure better data rates and improve astronaut communications at the Moon, and ultimately, Mars.
Today, SCaN supports over 100 NASA and non-NASA missions. Some missions look down at the Earth and observe changes; others observe the Sun's influence on the Earth; some study the Moon and the planets, while others study the origins of the universe.
SCaN: Enabling Exploration - from Apollo to Artemis and beyond.
Apollo 11: Seeing is Believing: On July 20, 1969, NASA astronauts Neil Armstrong and Buzz Aldrin, with Michael Collins orbiting above, became the first humans to land on another world, our Moon.
Affixed to the inside of the Eagle lander's door was a small, unconventional TV camera. The extraordinary images it captured showed Armstrong and Aldrin amid the "magnificent desolation" of the lunar surface.
Getting this incredible video to hundreds of millions of people back on Earth, gathered around countless television sets in rural homes, on city streets, and in remote villages around the globe, was up to the flexibility and resourcefulness of NASA's Manned Space Flight Network (MSFN) and DSN.
During lunar landing and liftoff, NASA "dishes" in Madrid, Spain, would provide tracking support for Apollo 11. But, at the time of the moonwalk, Madrid was facing away from the Moon and, thus, couldn't "see" it. So, the job of getting those first historic pictures down to the world fell to tracking stations in Australia and here in the United States.
When Armstrong finally started descending the Lunar Module ladder three hours after the Eagle had landed at Tranquility Base, a 64-meter antenna in Goldstone, California received the first downlink, and two-way communication from the surface of the Moon.
However, by the time Armstrong reached the foot of the ladder, Mission Control in Houston, Texas switched the transmission to Honeysuckle Creek's 26-meter antenna located outside of Canberra, Australia. The improvement in picture quality was extraordinary.
But, responsibility for voice communications remained at Goldstone.
These iconic words in history, "That's one small step for (a) man, one giant leap for mankind" ended their 240,000-mile journey to Earth at one location, while the pictures of Neil Armstrong speaking them came to be seen through another.
After almost nine minutes into the broadcast, a 64-meter dish at Parkes Observatory located in Parkes, New South Wales, Australia provided an even better picture. Television transmission would continue through July 23, 1969.
Behind these tracking stations were real people spending countless hours to make human exploration on the Moon possible.
"People everywhere appreciate the fact that the U.S. was willing to share its program so effectively with them by means of modern communications. People of many countries have told me personally that they certainly appreciate not only our technology but also our intebuild a better world through our space experiences. To those of you out there on the network who made all of the electrons go to the right places, at the right time — and not only during Apollo 11.... I would like to say, ‘Thank you.'" - Neil Armstrong to tracking network personnel, March 18, 1972.
Figure 1: This video commemorates the technological innovations that made possible the first live TV broadcast from the moon by the Apollo 11 crew on July 20, 1969 (video credit: NASA)
This video was aired when NASA Television was honored with a Primetime Emmy Award by the Academy of Television Arts & Sciences. The 2009 Philo T. Farnsworth Award recognizes the agency for engineering excellence and commemorates the 40th anniversary of the technological innovations that made possible the first live TV broadcast from the moon by the Apollo 11 crew on July 20, 1969.
Figure 2: SCaN Network Functional Responsibility (image credit: NASA) 2)
The SCaN Networks
SCaN: The SCaN networks—comprised of the Near Earth Network (NEN), the Space Network (SN), and the DSN—provide communications and navigation services over the full operational life cycle of a mission from launch to end of life and/or deorbit. While missions may have a desire to use specific resources in accordance with NPD 8074.1 Management and Utilization of NASA's Space Communication and Navigation Infrastructure, the SCaN network swill make the final decision on the provision of its assets.
DSN: The DSN, consisting of ground stations utilizing 34- and 70-meter antennas, is focused on providing support to missions operating beyond Geosynchronous Earth Orbit (GEO). Historically, the DSN has supported High Earth Orbit (HEO), Lunar, Lagrangian, and planetary missions. The DSN operations are the responsibility of the Jet Propulsion Laboratory (JPL) in Pasadena, California.
NEN: The NEN, consisting primarily of a combination of NASA, partner, and commercial ground stations with antennas up to 18 meters in diameter, is focused on supporting launch and operational activities in the Low Earth Orbit (LEO) range as well as GEO, Lunar, and Earth-Sun Lagrange points. Most NEN antennas slew very quickly, enabling the NEN to track Launch vehicles during ascent and high-speed low altitude missions with brief visibility windows. The NEN operations are the responsibility of Goddard Space Flight Center (GSFC) in Greenbelt, Maryland.
SN: The SN, consisting of a constellation of relay satellites in GEO pointing towards the Earth and the ground segment that operates the constellation, enables continuous communications services to missions operating in Medium Earth Orbit (MEO) and below with support provided to Highly Elliptical Orbit (HEO) when the orbit brings the spacecraft within range. The SN has continuous visibility to missions from Launch through LEO operations. NASA's SN is the responsibility of the GSFC.
Each of NASA's three DSN (Deep Space Network) sites has multiple large antennas and is designed to enable continuous radio communication between several spacecraft and Earth. All three complexes consist of at least four antenna stations, each equipped with large, parabolic dish antennas and ultra-sensitive receiving systems capable of detecting incredibly faint radio signals from distant spacecraft. 3)
The DSN's large antennas are focusing mechanisms that concentrate power when receiving data and when transmitting commands. The antennas must point very accurately towards the spacecraft, because an antenna can "see" only a tiny portion of the sky – not unlike looking at the sky through a soda straw.
To hear the spacecraft's faint signal, the antennas are equipped with amplifiers, but there are two problems. First, the signal becomes degraded by background radio noise, or static, emitted naturally by nearly all objects in the universe, including the sun and earth. The background noise gets amplified along with the signal. Second, the powerful electronic equipment amplifying the signal adds noise of its own. The DSN uses highly sophisticated technology, including cooling the amplifiers to a few degrees above absolute zero, and special techniques to encode signals so the receiving system can distinguish the signal from the unwanted noise.
Antenna stations are remotely operated from a signal processing center at each complex. The centers house electronic systems that point and control the antennas, receive and process data, transmit commands and generate spacecraft navigation data.
Once the data is processed at the complexes, it is transmitted to NASA's JPL (Jet Propulsion Laboratory) for further processing and distribution to science teams over a ground communications network.
The Australian complex is located 40 kilometers (25 miles) southwest of Canberra near the Tidbinbilla Nature Reserve. The Spanish complex is located 60 kilometers (37 miles) west of Madrid at Robledo de Chavela. The Goldstone complex is located on the U.S. Army's Fort Irwin Military Reservation, approximately 72 kilometers (45 miles) northeast of the desert city of Barstow, California. Each complex is situated in semi-mountainous, bowl-shaped terrains to shield against external radio frequency interference.
Figure 3: NASA has robotic explorers all over our solar system – and beyond! How do we communicate with these faraway spacecraft? With the big antennas of the Deep Space Network, or DSN! The DSN has three antenna complexes evenly spaced around the world in the United States, Spain, and Australia. Watch this virtual tour of each complex to learn more about each one! (video credit: NASA)
Figure 4: Deep Space Station-14 (DSS-14) located at Goldstone Deep Space Communications Complex (GDSCC), image credit: Goldstone Deep Space Communications Complex)
Status of the DSN
• January 22, 2021: A powerful new antenna has been added to the NASA Space Communications and Navigation's Deep Space Network (DSN), which connects us to the space robots exploring our solar system. Called Deep Space Station 56, or DSS-56, the dish is now online and ready to communicate with a variety of missions, including NASA's Perseverance rover when it lands on the Red Planet next month. 4)
DSN radio antennas communicate with spacecraft throughout the solar system. Previous antennas have been limited in the frequency bands they can receive and transmit, often being restricted to communicating only with specific spacecraft. DSS-56 is the first to use the DSN's full range of communication frequencies. This means DSS-56 is an "all-in-one" antenna that can communicate with all the missions that the DSN supports and can be used as a backup for any of the Madrid complex's other antennas.
With the addition of DSS-56 and other 34-meter antennas to all three DSN complexes, the network is preparing to play a critical role in ensuring communication and navigation support for upcoming Moon and Mars missions and the crewed Artemis missions.
The Deep Space Network is managed by NASA's Jet Propulsion Laboratory for the agency's Human Exploration and Operations' Space Communication and Navigation program.
The new 34-meter-wide dish has been under construction at the Madrid Deep Space Communications Complex in Spain since 2017. Existing antennas are limited in the frequency bands they can receive and transmit, often restricting them to communicating only with specific spacecraft. DSS-56 is the first to use the Deep Space Network's full range of communication frequencies as soon as it went online. This means DSS-56 is an "all-in-one" antenna that can communicate with all the missions that the DSN supports and can be used as a backup for any of the Madrid complex's other antennas.
"DSS-56 offers the Deep Space Network additional real-time flexibility and reliability," said Badri Younes, deputy associate administrator and program manager of NASA's Space Communications and Navigation (SCaN). "This new asset symbolizes and underscores our ongoing support for more than 30 deep space missions who count on our services to enable their success."
Figure 5: DSS-56 (Deep Space Station 56) is a powerful 34-meter-wide antenna that was added to the Deep Space Network's Madrid Deep Space Communications Complex in Spain in early 2021 (image credit: NASA/JPL-Caltech)
"The Deep Space Network is vital to so much of what we do – and to what we plan to do – throughout the solar system. It's what connects us here on Earth to our distant robotic explorers, and, with the improvements that we're making to the network, it connects us to the future as well, expanding our capabilities as we prepare human missions for the Moon and beyond," said Thomas Zurbuchen, associate administrator of the Science Mission Directorate at NASA's headquarters in Washington. "This latest antenna was built as an international partnership and will ultimately benefit all of humanity as we continue to explore deep space."
With DSS-56's increased flexibility came a more complex start-up phase, which included testing and calibration of a larger suite of systems, before the antenna could go online. On Friday, Jan. 22, the international partners who oversaw the antenna's construction attended a virtual ribbon-cutting event to officially mark the occasion – an event that had been delayed due to historic snowfall blanketing much of Spain.
"After the lengthy process of commissioning, the DSN's most capable 34-meter antenna is now talking with our spacecraft," said Bradford Arnold, DSN project manager at NASA's Jet Propulsion Laboratory in Southern California. "Even though pandemic restrictions and the recent weather conditions in Spain have been significant challenges, the staff in Madrid persevered, and I am proud to welcome DSS-56 to the global DSN family."
More About the Deep Space Network
In addition to Spain, the Deep Space Network has ground stations in California (Goldstone) and Australia (Canberra). This configuration allows mission controllers to communicate with spacecraft throughout the solar system at all times during Earth's rotation.
The forerunner to the DSN was established in January 1958 when JPL was contracted by the U.S. Army to deploy portable radio tracking stations in California, Nigeria, and Singapore to receive telemetry of the first successful U.S. satellite, Explorer 1. Shortly after JPL was transferred to NASA on Dec. 3, 1958, the newly-formed U.S. civilian space program established the Deep Space Network to communicate with all deep space missions. It has been in continuous operation since 1963 and remains the backbone of deep space communications for NASA and international missions, supporting historic events such as the Apollo Moon landings and checking in on our interstellar explorers, Voyager 1 and 2.
The Deep Space Network is managed by JPL for SCaN, which is located at NASA's headquarters within the Human Exploration and Operations Mission Directorate. The Madrid station is managed on NASA's behalf by Spain's national research organization, Instituto Nacional de Técnica Aeroespacial (National Institute of Aerospace Technology).
• March 4, 2020: Starting in early March, NASA's Voyager 2 will quietly coast through interstellar space without receiving commands from Earth. That's because the Voyager's primary means of communication, the Deep Space Network's 70-meter-wide radio antenna in Canberra, Australia, will be undergoing critical upgrades for about 11 months. During this time, the Voyager team will still be able to receive science data from Voyager 2 on its mission to explore the outermost edge of the Sun's domain and beyond. 5)
About the size of a 20-story office building, the dish has been in service for 48 years. Some parts of the 70-meter antenna, including the transmitters that send commands to various spacecraft, are 40 years old and increasingly unreliable. The Deep Space Network (DSN) upgrades are planned to start now that Voyager 2 has returned to normal operations, after accidentally overdrawing its power supply and automatically turning off its science instruments in January.
The network operates 24 hours a day, 365 days a year and is spread over three sites around the world, in California, Spain and Australia. This allows navigators to communicate with spacecraft at the Moon and beyond at all times during Earth's rotation. Voyager 2, which launched in 1977, is currently more than 11 billion miles (17 billion kilometers) from Earth. It is flying in a downward direction relative to Earth's orbital plane, where it can be seen only from the southern hemisphere and thus can communicate only with the Australian site.
Moreover, a special S-band transmitter is required to send commands to Voyager 2 - one both powerful enough to reach interstellar space and on a frequency that can communicate with Voyager's dated technology. The Canberra 70-meter antenna (called "DSS43") is the only such antenna in the southern hemisphere. As the equipment in the antenna ages, the risk of unplanned outages will increase, which adds more risk to the Voyager mission. The planned upgrades will not only reduce that risk, but will also add state-of-the art technology upgrades that will benefit future missions.
"Obviously, the 11 months of repairs puts more constraints on the other DSN sites," said Jeff Berner, Deep Space Network's chief engineer. "But the advantage is that when we come back, the Canberra antenna will be much more reliable."
The repairs will benefit far more than Voyager 2, including future missions like the Mars 2020 rover and Moon to Mars exploration efforts. The network will play a critical role in ensuring communication and navigation support for both the precursor Moon and Mars missions and the crewed Artemis missions. "The maintenance is needed to support the missions that NASA is developing and launching in the future, as well as supporting the missions that are operating right now," said Suzanne Dodd, Voyager project manager and JPL Director for the Interplanetary Network.
Figure 6: DSS-43 is a 70-meter-wide radio antenna at the Deep Space Network's Canberra facility in Australia. It is the only antenna that can send commands to the Voyager 2 spacecraft (image credit: NASA/Canberra Deep Space Communication Complex)
The three Canberra 34-meter antennas can be configured to listen to Voyager 2's signal; they just won't be able to transmit commands. In the meantime, said Dodd, the Voyager team will put the spacecraft into a quiescent state, which will still allow it to send back science data during the 11-month downtime.
"We put the spacecraft back into a state where it will be just fine, assuming that everything goes normally with it during the time that the antenna is down," said Dodd. "If things don't go normally - which is always a possibility, especially with an aging spacecraft - then the onboard fault protection that's there can handle the situation."
Berner says the work on the 70-meter antenna is like bringing an old car into the shop: There's never a good time to do it, but it will make the car much more dependable if you do.
The work on the Canberra DSN station is expected to be completed by January 2021. The DSN is managed by NASA's Jet Propulsion Laboratory for the agency's Human Exploration and Operations' Space Communication and Navigation program.
• October 1, 2014: NASA's newest Deep Space Network antenna, Deep Space Station 35 (DSS-35) in Canberra, Australia is now operational. DSS-35 is the first in a series of 34 meter Beam Waveguide (BWG) antennas to be built as part of the Deep Space Network Aperture Enhancement Project (DAEP). The ribbon-cutting ceremony will take place sometime in early 2015. 6)
Figure 7: Deep Space Station 35 before and after. The image on the left was taken at the groundbreaking ceremony in February 2010 and the image on the right is the completed antenna in September 2014 (image credit: NASA)
The BWG antenna is different than its predecessors because the antenna allows for multiple frequencies to be transmitted and received by the turning of the mirror in the pedestal room below the antenna. The antenna is much easier to maintain and signals can be translated on the spot to information that we can understand.
The Deep Space Network (DSN), which turned 50 on December 24, 2013, provides communication and tracking services to about 35 NASA and non-NASA missions beyond geosynchronous orbit (GEO). The DSN consists of three ground stations located approximately 120 degrees apart on Earth. This is to ensure that any satellite in deep space is able to communicate with at least one station at all times. The stations are located in Goldstone, California; Madrid, Spain; and Canberra, Australia.
CSIRO (Commonwealth Scientific and Industrial Research Organisation) performs the day-to-day operations at the Canberra Deep Space Communications Complex. NASA's Space Communication and Navigation (SCaN) Office has assigned operations and maintenance to the Jet Propulsion Laboratory (JPL).
• October 1, 2014: The Deep Space Network (DSN) consists of three complexes located approximately 120 degrees apart on Earth. The three complexes located in Goldstone, California; Madrid, Spain; and Canberra, Australia currently have a 70 meter antenna, one 34 meter High Efficiency (HEF) antenna and one or more 34 meter Beam Wave Guide (BWG) antennas. 7)
The 70 meter antennas were originally built as 64 meter antennas in the late 1960's to capture signals from the satellites exploring Venus and Mars. The antennas were upgraded to 70 meters in the mid 1980's when Voyager missions were exploring Uranus and Neptune.
The 34 meter High Efficiency (HEF) antennas were built in the 1980's and were the first to support X-band uplink, which was needed for missions exploring the outer planets. The 34 meter Beam Wave Guide (BWG) antennas, the newest of the group, were built in the 1990's. The BWG antenna routes energy between the reflector at the top of the dish and the pedestal room below ground. This allows for multiple feeds and amplifiers at multiple frequencies to be illuminated selectively by a single mirror and remove sensitive electronics from the tipping structure.
Starting in 2002, multiple studies were conducted to determine the most cost effective and technically feasible solution for retiring the 70 meter antennas. These antennas were built over 40 years ago and have begun showing their age. Parts have become difficult to find and maintenance costs are high and continue to increase. These antennas present both physical and technological limitations to potential upgrades needed to support future mission needs.
Figure 8: Four 34 meter antennas will not only have the same signal power as one 70 meter antenna, but will have the same landmass area (image credit: NASA)
The Space Communications and Navigation (SCaN) office decided to decommission the 70 meter antennas and replace them with arrays of four 34 meter antennas by 2025. An array of four antennas is easier to maintain and can provide the same/better performance as the 70 meter antenna. The array would consist of four antennas for the receiver function and one 34 meter antenna equipped with an 80 kW for the transmitter function. This plan is called the Deep Space Network (DSN) Aperture Enhancement Project (DAEP).
The first step in the DAEP is to have in three more 34 meter BWG antennas built in Canberra, Australia by 2018. Groundbreaking occurred in February 2010 with US and Australian government officials present.
By 2025, the 70 meter antennas at all three locations will be decommissioned for communications and replaced with the 34 meter BWG antennas arrays. All systems will be upgraded to have X-band uplink capabilities and both X- and Ka-band downlink capabilities.
1) Megan Wallace, "Space Communications and Navigation: Exploration Enabled, Then and Now," NASA, 1 July 2019, URL: https://www.nasa.gov/directorates/heo/scan/apollo50
2) "Space Communications and Navigation (SCaN)Mission Operations and Communications Services(MOCS)," NASA HQ, SCaN-MOCS-0001, Revision 2, March 15, 2019, URL: https://explorers.larc.nasa.gov/HPMIDEX/pdf_files/08a_SCaN-MOCS-0001_Rev%202_final.pdf
3) "DSN Complexes," NASA, 30 March 2020, URL: https://www.nasa.gov/directorates/heo/scan/services/networks/deep_space_network/complexes
4) "NASA's Deep Space Network Welcomes a New Dish to the Family," NASA/JPL, 22 January 2021, URL: https://www.jpl.nasa.gov/news/nasas-deep-space-network-welcomes-a-new-dish-to-the-family/?utm_source=iContact&utm_medium=email&utm_campaign=nasajpl&utm_content=weekly20210122-3
5) "NASA's Deep Space Antenna Upgrades to Affect Voyager Communications," NASA/JPL News, 4 March 2020, URL: https://www.jpl.nasa.gov/news/nasas-deep-space-antenna-upgrades-to-affect-voyager-communications/
6) "New Deep Space Network Antenna is Operational," NASA, 1 October 2014, URL: https://www.nasa.gov/directorates/heo/scan/news_dsn_dss35_operational.html
7) "Deep Space Network Aperture Enhancement Project (DAEP)," NASA, 1 October 2014, URL: https://www.nasa.gov/directorates/heo/scan/services/networks/txt_daep.html
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 (firstname.lastname@example.org).