SpaceX’s Starlink satellites can be used for navigation and global positioning in addition to their primary broadband internet function, a new research study suggests.
Engineering researchers outside SpaceX have found a way to use signals from the Starlink constellation for navigation similar to the capabilities provided by global positioning (GPS) satellites, which are used in the United States and several other countries. The study marks the first time that Starlink has been used for navigation by researchers outside of SpaceX, team members said.
Researchers triangulated signals from six Starlink satellites to determine a location on Earth with an accuracy of less than 27 feet (eight meters), the team reported in a statement. This is quite comparable to the typical GPS capabilities of a smartphone, which typically locates your position on Earth within 4.9m (16ft), depending on conditions.
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“We listened to the signal, then we designed sophisticated algorithms to locate our location, and we showed that it worked with great precision,” study author Zak Kassas, director of the Center for Automated Vehicles Research with Multimodal Assured Navigation (CARMEN) at Ohio State University, said in the statement.
“Although Starlink was not designed for navigation purposes, we have shown that it is possible to learn parts of the system well enough to use it for navigation,” said Kassas.
The researchers developed their navigation system without the help of SpaceX, nor any access to the data shared via the broadband connection. Instead, they used signals from multiple satellites and developed an algorithm to locate a position on Earth.
Then they set up an antenna on the University of California Irvine campus to try and find its location using Starlink. Their experiment placed the antenna’s estimated position, using Starlink signals, within 7.7 m (25 feet) of its actual position.
The algorithm and Starlink working together are of comparable accuracy to previous projects the team worked on, Kassas said. Other constellations of low-earth orbiting satellites focused on locations about 75 feet (23 meters) away. An independent project with the US Air Force, aimed at locating high altitude aircraft locations, produced an accuracy of 16.5 feet (5 meters).
Kassas noted that Starlink’s accuracy, using this methodology, will increase as more satellites in the fleet fly into orbit. SpaceX now has around 1,700 operating satellites, the team said, but the company hopes to launch more than 40,000 into orbit. (Recent launches have been delayed due to a shortage of liquid oxygen induced by higher medical needs during the COVID-19 pandemic.)
The researchers suggested that this method of using Starlink navigation could complement traditional GPS navigation, the latter with vulnerabilities. Since GPS has been around for a generation (over 30 years) and has a well-known signal, it’s easy to use on smartphones or vehicles – but also more “vulnerable to attack,” the team said.
Starlink also has an advantage with its altitude, orbiting about 750 miles (1,200 km) much closer to Earth than GPS orbiting geosynchronously at nearly 23,500 miles (37,800 km). While GPS has the advantage of being dedicated to a region of the Earth, but the disadvantage of its remote position is that the signal is more vulnerable to natural or man-made interference.
Starlink satellites are also launched more frequently – once every few weeks, typically – than GPS (once every few months or years), allowing Starlink to have more frequent hardware upgrades.
Coincidentally, in recent years, SpaceX has launched several GPS satellites for the US Space Force. Founder Elon Musk has so far not commented on the new study on Twitter in recent days.
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