NASA has demonstrated a new way for satellites to navigate without GPS by using the objects around them as landmarks in space.
NASA’s Starling mission has reached another milestone in spacecraft autonomy with a new system that can determine a satellite’s position by using other objects in space as reference points rather than depending on a traditional navigation network.
The FALCON (Fast Autonomous Lost-in-space Catalog-based Optical Navigation) technology demonstration represents another step toward spacecraft that can operate with greater independence. As NASA prepares for more missions beyond Earth’s orbit, systems such as FALCON could support lunar satellite swarms, distributed science missions, and future human exploration.
Navigating Space Without GPS
Most satellites rely on GPS for navigation, but those signals can become unreliable or unavailable around the Moon and in deep space. FALCON is a joint flight experiment developed by NASA and EraDrive, a startup spun out from Stanford University.
The system combines EraDrive’s Era-Core flight software and embedded algorithms with Starling’s cameras and an onboard catalog of known satellites. Together, these tools allow the spacecraft to navigate independently of GPS while also improving its awareness of nearby objects in space.
“FALCON is yet another success for the Starling demonstration mission. The results from FALCON can have far-reaching implications for on-orbit space-traffic monitoring, collision avoidance, and alternative navigation,” said Roger Hunter, program manager for NASA’s Small Spacecraft and Distributed Systems program at NASA’s Ames Research Center in California’s Silicon Valley. “The number of ‘firsts’ from Starling just keeps growing.”
Using Other Space Objects as Reference Points
The FALCON demonstration tested two complementary capabilities by making new use of Starling’s onboard star-tracker cameras. These standard spacecraft instruments normally identify bright objects in space to help determine a spacecraft’s orientation and position.
During position, navigation, and timing experiments, FALCON compared objects seen by Starling’s cameras, including other spacecraft and orbital debris, with a catalog of known space objects maintained and made publicly available by the U.S. Department of War. Once those objects were identified and verified, FALCON used them as reference points to calculate Starling’s orbit.
In separate tests, the system also improved estimates of the orbits of objects observed by Starling’s cameras. The mission team loaded a complete catalog of approximately 20,000 space objects and their predicted orbits onto the spacecraft.
FALCON then compared those catalog predictions with observations made by Starling’s cameras. Using both sources of information, it estimated Starling’s position and the positions of other objects with greater precision than the existing catalog data. Over a three-day period, FALCON improved the known orbits of more than 200 objects without any intervention from ground operators.
A First for Autonomous Optical Navigation
FALCON’s self-orbit determination capability marks a first for spacecraft using optical cameras to navigate according to their position relative to other objects in space. In a separate achievement, the onboard catalog-update experiments generated more accurate object position predictions aboard Starling than those supplied by ground stations.
Networks of GPS-free satellites could become especially important for future human missions to the Moon or Mars, where coordinated spacecraft may be needed to support operations on the surface.
Precise spacecraft positioning is also essential for many science missions because researchers need to correctly align measurements collected from multiple locations in space. For space traffic management, autonomous navigation and onboard catalog updates could reduce dependence on ground networks while improving collision avoidance.
Building More Independent Spacecraft
The FALCON experiment also demonstrates NASA’s role in supporting commercial space technology. The work began as a University SmallSat Technology Partnerships project and later developed into EraDrive, which is now commercializing its Era-Core software and related hardware for wider use.
Starling provided a real-world testing platform for the technology, demonstrating how advanced flight software can help turn satellites into autonomous navigators.
Later this year, Starling, which launched in 2023, will expand the FALCON experiment using Era-Core. Its four-spacecraft swarm will share tracking information and work together to refine their positions.
NASA’s Ames Research Center in California’s Silicon Valley leads the Starling mission. NASA’s Small Spacecraft and Distributed Systems program, based at Ames and within the Research and Technology Mission Directorate, funds and manages the Starling mission.
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