Move Over, GPS: Navigation Satellites in Low Earth Orbit Are Making a Comeback With 100x Stronger Signals
Featured image: Artist’s concept of a Xona Pulsar satellite in low Earth orbit; credit: Xona Space Systems
For more than three decades, GPS has been the silent backbone of modern civilization, guiding everything from airplane landings to smartphone maps. But its signals, broadcast from 20,200 kilometers up, are whisper-weak. A simple $30 jammer can block them across a city block. In wartime Ukraine, Russian electronic warfare has rendered GPS-guided munitions ineffective.
Now a new generation of navigation satellites is making a comeback by moving closer to Earth. Startups and space agencies are deploying navigation payloads in low Earth orbit, about 1,080 kilometers up, where signals arrive 100 times stronger than GPS and can penetrate buildings, tree canopy, and deliberate interference.
“Navigation satellites in LEO are providing 100 times stronger signal strength compared to GPS,” Jeremy Hsu reports in Ars Technica’s July 16 feature on the emerging industry.
Xona’s Pulsar Constellation
The leading commercial player is Xona Space Systems, a Burlingame, California-based startup founded in 2019 by veterans of SpaceX and Blue Origin. The company plans to deploy 258 Pulsar satellites in LEO, offering centimeter-level positioning with cryptographic anti-spoof protection.
The signal strength advantage is dramatic. Pulsar signals are 100 times stronger than the civilian GPS L1 C/A signal, reducing a jammer’s effective area by 95 percent. In live-sky jamming tests conducted across multiple countries, the system maintained accurate positioning where GPS was completely blocked. The system also enables indoor positioning and urban canyon navigation that GPS cannot achieve.
Xona’s satellites operate on dual-band frequencies adjacent to GPS L1 and L5, using a modulation scheme that concentrates power in the central lobe to avoid interfering with existing GNSS services. The system is backward-compatible with existing GPS receivers through a firmware or software update, meaning users do not need new hardware.
The company has raised more than $150 million across eight rounds from investors including Craft Ventures, Mohari Ventures, Toyota Ventures, Lockheed Martin Ventures, and Trimble Ventures, plus a $20 million award from the US Space Force.
From Transit to Pulsar
The concept of LEO navigation is not new. The US Navy’s Transit system, operational from 1964 to the 1990s, used 36 LEO satellites to provide positioning for Polaris submarines using Doppler shift measurements. But Transit could only fix positions every one to two hours, making it useless for real-time navigation. GPS replaced it with 24 to 31 satellites in medium Earth orbit providing continuous coverage.
What has changed is launch cost. The SpaceX-driven collapse in orbital delivery prices makes it economically feasible to build and maintain a 258-satellite LEO constellation, something that was financially impossible a decade ago.
How the Technology Works
LEO’s proximity to Earth provides the core advantage. At about 1,080 kilometers, Pulsar satellites are about 20 times closer than GPS satellites at 20,200 kilometers. Because signal power follows the inverse square law, the difference translates into about 100 times more signal power reaching a receiver on the ground.
The rapid motion of LEO satellites across the sky also provides a benefit: receivers can resolve carrier-phase ambiguities in seconds rather than the 10-plus minutes required for traditional precise point positioning with GPS.
LEO also avoids the Van Allen radiation belts, allowing the use of commercial off-the-shelf electronics and enabling faster technology upgrades. Xona has developed a patented distributed clock architecture that eliminates the need for onboard atomic clocks.
The target accuracy is 2 centimeters horizontal and 4 centimeters vertical, with timing precision under 10 nanoseconds. A cryptographic authentication watermark, already demonstrated on the company’s Pulsar-0 test satellite, prevents spoofing.
Deployment Timeline
Xona’s first demo satellite, Huginn, launched in May 2022. Its first production-class satellite, Pulsar-0, launched in June 2025 and achieved a signal-in-space user-range error of just 43 millimeters, later improved to 15 millimeters via a software update.
The first six production satellites, two built in-house and four contracted from Belgium’s Aerospacelab, are scheduled to launch in October 2026. Early commercial service is expected to begin in 2027 with mid-latitude coverage, scaling to a full 258-satellite constellation in the following years.
Challenges and Competition
The biggest challenge is constellation size. LEO requires about 10 times more satellites than MEO for equivalent global coverage. Atmospheric drag at about 1,080 kilometers causes orbital decay, requiring station-keeping propellant and rapid replenishment, especially during periods of high solar activity.
Coverage gaps remain a risk with fewer satellites. Persistent timing service requires at least 16 satellites in view for urban users, and centimeter-level positioning requires four or more.
Competition is emerging. TrustPoint of Virginia is planning a 300-satellite LEO navigation constellation using C-band frequencies, targeting 2027 service. Europe’s ESA Celeste mission captured its first LEO navigation signal in April 2026. China has experimental LEO PNT satellites in orbit.
But the broader context may be the biggest driver. GPS jamming has reached record levels worldwide, disrupting commercial flights, maritime shipping, and civilian smartphone navigation. The Russia-Ukraine war demonstrated that even the most sophisticated GPS-guided weapons can be rendered ineffective by electronic warfare. As Ohio State navigation researcher Zak Kassas told Ars Technica, “We need an extra layer of redundancy.”