In 2019, SpaceX launched the first 60 of its Starlink satellites in an effort to begin creating a constellation of satellites capable of providing low latency, wide bandwidth global Internet services from low Earth orbit (LEO). With more than 700 satellites already launched, and a goal for thousands to eventually be in orbit, the growing constellation has led researchers at the Radionavigation Laboratory at the University of Texas at Austin to the discovery of a side benefit: an enhanced Global Positioning System (GPS).
In their recently published study, which was funded by the U.S. Army, lead researchers Todd Humphreys and Peter Iannucci have developed a software solution that would allow altered GPS signals to be amplified by Starlink satellites. The result could potentially mean unjammable, precise location data at much lower costs.
Current GPS features a much smaller constellation—only about 30 satellites—orbiting 20,000 kilometers above Earth. The satellites constantly send back radio signals with their exact position and time. The receivers use that data to calculate positioning, which is usually within a few meters. The downside is that the signals are greatly weakened once they arrive and can be easily interfered with. From a military standpoint, that could be detrimental during warfare.
LEO satellites orbit around 1,100 kilometers from Earth, creating signals 1,000 times stronger. Since their constellations are expected have approximately 12,000 satellites, interfering with them would be much more difficult. The satellites are also like space routers providing 100 megabits per second.
“There are so few bits per second available for GPS transmissions that they can’t afford to include fresh, highly accurate data about where the satellites actually are,” Iannucci said. “If you have a million times more opportunity to send information down from your satellite, the data can be much closer to the truth.”
The research team’s “fused LEO navigation” solution would benefit both the military and civilians, as well as eliminate the high costs that would be associated with having to develop a new network of LEO satellites. It would involve giving satellites a software upgrade to allow for positioning and navigations services. According to the researchers, satellites upgraded with GPS receivers would use algorithms capable of pinpointing locations within centimeters instead of meters. In essence, instead of the computing being done on the ground, it would be done in orbit.
Another benefit would be the reach of the LEO navigation system. The research states that this solution could provide continuous navigation service to 99.8 percent of the world’s population while using less than 1 percent of Starlink’s downlink capacity and less than 0.5 percent of its energy capacity.
While the research is exciting, it does come with some downsides. The software itself may be inexpensive, but using SpaceX satellites would likely come at a steep price, as would the development of new microprocessors for smart devices. Another limitation is the satellites themselves. Currently, Starlink doesn’t operate at latitudes above 60 degrees, which means places like Alaska, Canada, Finland and others would be left out.
Interested in learning more about satellite constellations? Check out The Era of Satellite Constellations Has Arrived and The Space-Based Internet Battle Is Heating Up.