Move over, GPS: Navigation satellites in low-Earth orbit are making a comeback
Ars Technica · LC · trust 50/100
That GPS forerunner you forgot is coming back in style Move over, GPS: Navigation satellites in low-Earth orbit are making a comeback Xona aims to deploy 258 satellites into low-Earth orbit as a GPS alternative.
53 An illustration of a Pulsar satellite developed by Xona Space Systems for providing PNT services from low-Earth orbit. Credit: Xona Space Systems An illustration of a Pulsar satellite developed by Xona Space Systems for providing PNT services from low-Earth orbit. Credit: Xona Space Systems Text settings Story text Size Small Standard Large Width * Standard Wide Links Standard Orange * Subscribers only Learn more Minimize to nav New navigation satellites in low-Earth orbit could provide 100 times stronger signal strength compared to GPS and other global navigation satellite systems operating from higher orbital altitudes—enabling greater location accuracy within dense cities, under thick foliage, and even inside buildings. Such signals would also likely prove more resilient to interference at a time when commercial flights, maritime shipping, and even various smartphone apps face increasingly widespread disruption from GPS jamming .
That vision may start to take shape when the first six production satellites of California-based Xona Space Systems are scheduled to launch in October 2026, with early service starting in 2027. Once the full constellation of 258 Pulsar satellites has been launched in the following years, Xona claims that customers will be able to accurately pinpoint their locations anywhere on Earth to within several centimeters.
“That added power means that we can get into that indoor environment that GPS can’t get to today,” Adrien Perkins , co-founder and VP of engineering at Xona Space Systems, told Ars. “Our higher power allows you to get into those jamming environments a lot further than you would with GPS by itself.”
Xona has already launched its first satellite, called Pulsar-0, aboard a SpaceX Falcon 9 rocket rideshare mission on July 1, 2025. The Pulsar-0 satellite has participated in multiple “live-sky jamming tests across multiple countries” to show how having signals 100 times stronger than GPS can help to reduce a jammer’s effective area by 95 percent, according to a Xona blog post . The company also tested an anti-spoof watermark built into Pulsar signals to help receivers authenticate the satellite signals and used software updates to improve the initial satellite’s “native positioning accuracy” from a 4.2-centimeter ranging error to 1.5-centimeter accuracy.
Like other global navigation satellite systems that deliver positioning, navigation, and timing (PNT) services, Pulsar satellites could also start providing intermittent timing signals to customers in mid-latitude regions following the launch of the six production satellites in October. Xona has already signed up several precision-timing customers to use Pulsar satellite signals in timing and synchronization services for financial markets, telecommunications, data centers , and transportation systems.
Xona expects its satellites to eventually deliver a timing reference accurate to within 10 nanoseconds. But unlike GPS satellites that carry expensive atomic clocks for accurate timekeeping, Pulsar satellites would rely on a much cheaper software-based solution for precision timing.
The Pulsar timing services would become more persistent and available in urban environments once the constellation grows to about 16 satellites in orbit, enabling at least one satellite to be in view on a regular basis, according to Xona. The company also described centimeter-level positioning capability as becoming possible with four Pulsar satellites in view over a region, which it expects to accomplish for “priority regions” before the full constellation is completed.
The first customers for Xona and other companies planning satellite navigation systems in low-Earth orbit (LEO) will likely be “organizations that place an exceptionally high value on availability, resilience, integrity, authentication, and precision, and are already accustomed to paying for premium PNT services,” Zak Kassas , director of the Autonomous Systems Perception, Intelligence, and Navigation (ASPIN) Laboratory at The Ohio State University, told Ars. He suggested that such customers would be “defense and national security users and government agencies responsible for resilience.”
Using satellites in LEO to deliver location and timekeeping services is “both a blessing and a curse,” Kassas explained in his column for Inside GNSS . The blessing is that LEO satellites can provide stronger signals to ground receivers by operating closer to Earth, and their relatively fast movements across the sky can be measured in ways that provide additional information useful for geolocation and navigation on Earth.
The curse is that hundreds of LEO satellites are required to reliably provide near-instantaneous location and timing services across the entire world. The prospect of deploying so many satellites is no longer daunting since the advent of lower-cost rocket launches driven by SpaceX , which has enabled the growing megaconstellations with thousands of satellites such as Starlink . But it represented a serious constraint during the US military’s deployment of the world’s first satellite navigation system, called Transit, in the 1960s.
Before GPS, there was Transit. The idea for the Transit satellite system began with physicists at Johns Hopkins University’s Applied Physics Laboratory figuring out how to calculate the orbit of the Soviet Union’s Sputnik-1, which had become the world’s first artificial satellite. Their work relied on calculating the Doppler shift—the change in observed signal frequency—of radio signals coming from Sputnik as it passed overhead. But additional discussions led to the realization that the Doppler shift from a satellite with a known position could also be used to calculate the location of a signal receiver on Earth.…
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