SpaceX satellite signals used like GPS to pinpoint location on Earth

Engineering researchers person developed a method to usage signals broadcast by Starlink net work satellites to accurately find a presumption present connected Earth, overmuch similar GPS does. It is the archetypal clip the Starlink strategy has been harnessed by researchers extracurricular SpaceX for navigation.

The Starlink satellites, sent into orbit by Elon Musk's SpaceX, are designed to supply broadband net connections successful remote locations astir the world. The researchers utilized signals from six Starlink satellites to pinpoint a location connected Earth wrong 8 meters of accuracy.

Their findings, shared contiguous (Sept. 22, 2021) astatine the Institute of Navigation GNSS yearly gathering successful St. Louis, whitethorn supply a promising alternate to GPS. Their results volition beryllium published successful the upcoming contented of the diary IEEE Transactions connected Aerospace and Electronic Systems.

The researchers did not request assistance from SpaceX to usage the satellite signals, and they emphasized that they had nary entree to the existent information being sent done the satellites—only to accusation related to the satellite's determination and movement.

"We eavesdropped connected the signal, and past we designed blase algorithms to pinpoint our location, and we showed that it works with large accuracy," said Zak Kassas, manager of the Center for Automated Vehicles Research with Multimodal Assured Navigation (CARMEN), a multi-institution proscription halfway housed astatine The Ohio State University.

"And adjacent though Starlink wasn't designed for navigation purposes, we showed that it was imaginable to larn parts of the strategy good capable to usage it for navigation."

CARMEN is 1 of 4 precocious awarded U.S. Department of Transportation University Transportation Centers. Kassas is an adjunct prof of electrical and machine engineering astatine Ohio State and an subordinate prof astatine the University of California, Irvine.

For this research, Kassas and his probe squad studied the Starlink strategy and analyzed signals being sent by the satellites. They developed an algorithm that could usage the signals of aggregate satellites to find a presumption connected Earth. Then, they acceptable up an antenna connected the field of UCI and tried to usage the web to pinpoint the antenna's location.

Using Starlink, they identified the antenna's determination wrong astir 7.7 meters. GPS, by comparison, mostly identifies a device's determination wrong 0.3 and 5 meters. The squad has utilized akin techniques with different debased Earth orbit outer constellations, but with little accuracy, pinpointing locations wrong astir 23 meters, Kassas said. The squad has besides been moving with the U.S. Air Force to pinpoint locations of high-altitude aircraft; they were capable to travel wrong 5 meters utilizing land-based cellular signals, Kassas said.

SpaceX has immoderate 1,700 satellites successful Earth's debased orbit, meaning they ellipse the satellite astir 1,200 km from Earth's surface. SpaceX yet plans to motorboat much than 40,000 satellites.

Kassas said arsenic the Starlink constellation grows, so, too, volition the accuracy of his team's navigation and geo-location method with its signals.

Their find could let the authorities oregon different agencies to usage Starlink's satellites arsenic an alternate navigation system—and possibly, a much unafraid one—to GPS, which powers astir each navigation systems astir the world, Kassas said.

GPS has been successful spot for much than 30 years and its signals are well-known, akin to open-source software, Kassas said. That is an plus to companies that make GPS receivers successful smartphones, wearable fittingness devices and vehicles, but it besides makes the strategy susceptible to attacks. GPS satellites are besides farther distant from Earth than low-Earth orbiting systems, making their signals weaker, and truthful much susceptible to interference.

Jamming attacks connected GPS signals tin instrumentality down GPS signals altogether, which has been a increasing occupation for aviation. Spoofing attacks connected GPS tin manipulate wherever a fixed conveyance appears successful systems designed to show locations and forestall vehicles from overlapping routes; attacks tin besides instrumentality implicit a vehicle's path—for example, immoderate attacks person overtaken subject and civilian drones, maritime vessels, and adjacent Tesla's autopilot.

The Starlink strategy is appealing to navigation experts, Kassas said, due to the fact that the signals, until now, person been private—SpaceX has not shared them with governments oregon researchers. Starlink satellites are person to Earth than GPS satellites are, making their signals overmuch stronger and little susceptible to interference.

"The important drawback present is that we are not 'listening' successful connected what is being sent implicit these satellites," Kassas said. "We learned the signals conscionable good capable to harness them for navigation purposes."

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