GPS World

Tag: Space Communications and Navigation

  • NASA moon mission set to break record in navigation signal test

    NASA moon mission set to break record in navigation signal test

    Collaboration powers GPS and Galileo navigation experiment

    By Danny Baird
    ​NASA’s Goddard Space Flight Center

    As the Artemis missions journey to the Moon and NASA plans for the long voyage to Mars, new navigation capabilities will be key to science, discovery and human exploration.

    Through NASA’s Commercial Lunar Payload Services initiative, Firefly Aerospace of Cedar Park, Texas, will deliver an experimental payload to the Moon’s Mare Crisium basin. NASA’s Lunar GNSS Receiver Experiment (LuGRE) payload will test a powerful new lunar navigation capability using Earth’s GNSS signals at the Moon for the first time.

    “In this case, we are pushing the envelope of what GNSS was intended to do — that is, expanding the reach of systems built to provide services to terrestrial, aviation, and maritime users to also include the fast growing space sector,” said J.J. Miller, deputy director of Policy and Strategic Communications for NASA’s Space Communications and Navigation (SCaN) program. “This will vastly improve the precision and resilience of what was available during the Apollo missions, and allow for more flexible equipage and operational scenarios.”

    LuGRE — developed in partnership with the Italian Space Agency (ASI) – will receive signals from both GPS and Galileo, and use them to calculate the first-ever GNSS location fixes in transit to the Moon and on the lunar surface.

    “Space missions close to Earth have long relied on GNSS for their navigation and timekeeping,” said Joel Parker, LuGRE principal investigator at NASA’s Goddard Space Flight Center in Greenbelt, Maryland. “In recent years, NASA and the international community have pushed the boundaries of what was considered possible by using these techniques in the Space Service Volume and beyond.”

    This graphic details the different areas of GNSS coverage. (Image: NASA/Danny Baird)
    This graphic details the different areas of GNSS coverage. (Image: NASA/Danny Baird)

    Missions in the GNSS Space Service Volume — from about 1,800 miles to 22,000 miles in altitude — receive signals that spill past Earth’s edge from GNSS satellites on the opposite side of the planet. The first Space Service Volume experiments occurred around the dawn of the new millennium. Since then, numerous missions in the Space Service Volume have reliably used GNSS to navigate.

    In 2016, the NASA’s Magnetospheric Multiscale Mission (MMS) employed GPS operationally at a record-breaking 43,500 miles from Earth. Then, in 2019, MMS broke its own record by fixing its location with GPS at 116,300 miles from Earth — nearly halfway to the Moon.

    At these extreme altitudes, missions need extremely sensitive GNSS receivers. The LuGRE mission will use a specialized weak-signal receiver developed by Qascom, an Italian company specializing in space cybersecurity and satellite navigation security solutions, and funded by ASI.

    LuGRE teams are now testing the payload in preparation to deliver it for integration onto the Firefly “Blue Ghost” lander in November of this year. Launch is slated for no earlier than 2024 from Cape Canaveral, Florida, aboard a SpaceX Falcon 9 rocket.

    During the multi-week flight to the Moon, LuGRE will collect GNSS signals and perform navigation experiments at different altitudes and in lunar orbit. After landing, LuGRE will deploy its antenna and begin 12 days of data collection, with the potential for extended mission operations. NASA and ASI will process and analyze data downlinked to Earth, and then share results publicly.

    “LuGRE is the latest effort in a long line of missions designed to expand high-altitude GNSS capabilities,” said Fabio Dovis, LuGRE co-principal investigator, ASI. “We’ve developed a cutting-edge experiment that will serve as the foundation for operational GNSS systems at the Moon.”

    The LuGRE mission seeks to spark further development of GNSS-based navigation capabilities near and on the Moon, even as NASA plans to begin using high-altitude GNSS operationally for future lunar missions. NASA and ASI will bring the results of this work forward to the space community through the International Committee on GNSS, a United Nations forum focused on ensuring the interoperability of GNSS signals. These capabilities are also a key stepping stone towards building LunaNet, an architecture that will unify cooperative networks into seamless lunar communications and navigation services.

    Artistic rendering of LuGRE and the GNSS constellations. In reality, the Earth-based GNSS constellations take up less than 10 degrees in the sky, as seen from the Moon. (Image: NASA/Dave Ryan)
    Artistic rendering of LuGRE and the GNSS constellations. In reality, the Earth-based GNSS constellations take up less than 10 degrees in the sky, as seen from the Moon. (Image: NASA/Dave Ryan)

    “The lunar deliveries we’re sourcing from commercial vendors are providing a number of innovative new technologies and opportunities to conduct experiments with affordable access to the lunar surface,” said Jay Jenkins, Commercial Lunar Payload Services Program executive. “LuGRE is one example of the progress that government and industry can make when united in their exploration objectives.”

    Developing new uses of GNSS for emerging space operations is a priority for the SCaN program at NASA headquarters, as the lead organization responsible for implementing guidance from Space Policy Directive-7, which directs NASA to develop requirements for GPS support of space operations and science in higher orbits and beyond into cislunar space.

  • NASA advancing GNSS capabilities for spacecraft

    NASA advancing GNSS capabilities for spacecraft

    NASA’s Space Communications and Navigation (SCaN) program is developing capabilities that will allow missions at high altitudes to take advantage of GNSS signals for timing and navigation, including the Artemis missions to the Moon.

    Interoperability of the GNSS constellations will be key for spacecraft at higher altitudes where GNSS signals are less plentiful. The program will rely on the four global constellations (GPS, Galileo, GLONASS and BeiDou) and the two regional systems operated by India and Japan.

    SCaN is supporting flight experiments that will help develop multi-GNSS capabilities for spacecraft, such as Bobcat-1, developed by NASA’s Glenn Research Center in Cleveland and Ohio University.

    Bobcat on the Prowl

    Bobcat-1, shown with its deployable antenna stowed, will experiment with the GNSS inter-constellation time offset from low-Earth orbit. (Photo: NASA)
    Bobcat-1, shown with its deployable antenna stowed, will experiment with the GNSS inter-constellation time offset from low-Earth orbit. (Photo: NASA)

    Bobcat-1 was selected by the CubeSat Launch Initiative in 2018 to study GNSS signals from 250 miles overhead. The small satellite launched to the International Space Station aboard a Northrop Grumman Cygnus spacecraft on Oct. 2, 2020.

    On Nov. 5, the space station released the CubeSat to begin its mission. The spacecraft will orbit for about nine months, measuring signals from different GNSS constellations. Engineers will use these measurements to better understand GNSS performance, specifically focusing on timekeeping variations between the constellations.

    “GNSS users at high altitudes see fewer satellites,” said Bobcat Co-Principal Investigator Frank Van Grass of Ohio University. “Time offsets between the constellations can be measured by the CubeSat and provided to these users to improve their positioning performance,”

    SCaN Testbed

    Bobcat-1 builds on the legacy of the SCaN Testbed, which demonstrated multi-GNSS capabilities on the space station from 2012 to 2019. The GPS and Galileo Receiver for the International Space Station (GARISS) — an instrument developed in collaboration between NASA and ESA (European Space Agency) — received signals from both GPS and Galileo, the GNSS constellation operated by the European Union.

    The SCaN Testbed prior to launch to the International Space Station. (Photo: NASA)
    The SCaN Testbed prior to launch to the International Space Station. (Photo: NASA)

    The SCaN TestBed also laid the foundation for the Lunar GNSS Receiver Experiment (LuGRE), a Commercial Lunar Payload Services payload being developed in partnership with the Italian Space Agency. The payload will receive signals from both GPS and Galileo and is expected to obtain the first-ever GNSS fix on the lunar surface.

    GNSS PNT Policy and Advocacy

    While NASA engineers develop the technologies necessary for multi-GNSS navigation at ever-higher altitudes, the SCaN team works with stakeholders in the U.S. government and internationally to advance GNSS interoperability in the policy sphere. They consult on the United Nations International Committee on GNSS, helping develop additional capabilities in the Space Service Volume and beyond.

    NASA recently worked to publish GPS antenna patterns from GPS satellites that launched between 1997 and 2000, collaborating with the U.S. Space Force, the U.S. Coast Guard and Lockheed Martin, who built the satellites. The PNT team is also working to facilitate publication of antenna patterns for more recent GPS satellites.

    With this data, mission planners can better assess the performance of GNSS in high-Earth orbit and lunar space. This forthrightness also encourages other GNSS providers to be similarly transparent.

    The Goddard PNT policy team received a 2019 Agency Honor Award for their advocacy of NASA’s interests in GNSS. From let are Frank Bauer, Jenny Donaldson, J.J. Miller, Ben Ashman and Joel Parker. Not pictured, Lauren Schlenker. (Photo: NASA)
    The Goddard PNT policy team received a 2019 Agency Honor Award for their advocacy of NASA’s interests in GNSS. From let are Frank Bauer, Jenny Donaldson, J.J. Miller, Ben Ashman and Joel Parker. Not pictured, Lauren Schlenker. (Photo: NASA)

    “GNSS capabilities continue to revolutionize the ways spacecraft navigate in near-Earth space and beyond,” said NASA navigation engineer Joel Parker. “NASA’s longstanding relationships with the GNSS providers have advanced these capabilities to new heights and support the Artemis missions on and around the Moon.”