NASA's Starling Satellites Prove They Can Navigate Without GPS

NASA's Starling mission, a swarm of four cubesats in low Earth orbit, has demonstrated a way for spacecraft to navigate by using other satellites as landmarks instead of GPS. The three-year-old technology demonstration has been extended until at least 2028, NASA announced on Aug. 17, to get more out of the onboard experiment, called FALCON — Fast Autonomous Lost-in-space Catalog-based Optical Navigation — developed with industry partner EraDrive, a company that grew out of a Stanford University group.

FALCON uses Starling's cameras to observe nearby satellites and other objects, matching them against an onboard catalog of roughly 20,000 objects drawn from publicly available Department of Defense records, and uses the verified objects as reference points to determine the spacecraft's own orbit. NASA said this self-orbit determination is a first for a spacecraft using optical cameras alone, and the work was completed autonomously, without ground operators, in just three days. The experiment also produced better position estimates for 200 individual objects than those in the existing DoD catalog.

GPS works well in Earth orbit but becomes far less useful for missions travelling farther out, such as to the Moon, where NASA aims to land astronauts again as soon as 2028 on the Artemis IV mission as part of a plan to build a lunar base. Lunar orbits carry their own hazards: in 2025, Canada's Outer Space Institute reported that uneven concentrations of mass inside the Moon, called mascons, can pull on orbiting spacecraft and in some cases cause them to crash into the surface.

Starling's four spacecraft fly at an altitude of about 350 miles (565 km), roughly 6 miles higher than originally planned, after SpaceX warned that the original plan risked bringing Starling close to its own Starlink satellites orbiting at 340 miles. "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.