WASHINGTON, July 16 — A new navigation system that operates in low Earth orbit is challenging the decades-old architecture of the Global Positioning System, according to technical specifications and company filings. Xona Space Systems’ PULSAR network uses satellites at altitudes between 160 km and 2,000 km, a region known as low Earth orbit. Traditional GPS satellites fly much higher, at approximately 20,200 km in medium-Earth orbit.
The U.S. government currently operates 31 GPS satellites in that higher band. The difference in altitude produces a measurable gap in performance.
Signals from LEO satellites reach the ground with up to 100 times the strength of GPS signals, according to the company. That stronger signal means lower latency and better resistance to interference and jamming.
Trade-offs in orbit
The closer orbit comes with trade-offs. Each LEO satellite covers a smaller footprint on the ground than a GPS satellite does. To achieve global coverage, Xona plans to deploy 258 satellites.
The lower orbit also means the satellites move faster relative to the ground, which demands more complex ground infrastructure and more capable user equipment than GPS requires. The concept of using low Earth orbit for navigation is not new.
The U.S. Navy’s Transit system, which began operating in the 1960s, used six satellites in polar LEO to guide ships. What has changed, according to engineers familiar with the field, is the cost of building and launching small satellites. Miniaturization of electronics and the rise of commercial launch services have made LEO constellations economically feasible in a way they were not during the Cold War.
Resistance to jamming
The signal strength advantage is the most significant operational difference. GPS signals, traveling from 20,200 km away, arrive at the receiver with very low power. They are easy to jam or spoof with relatively cheap equipment — a vulnerability that has been documented in conflict zones and in urban black-market GPS spoofing cases.
PULSAR’s 100-times-stronger signal makes jamming far harder, because an adversary would need proportionally more power to overwhelm it. That characteristic has drawn interest from defense and security analysts who track the vulnerability of GPS-dependent systems.
The U.S. military has for years sought alternative positioning, navigation and timing (PNT) sources that do not rely solely on the GPS constellation. Xona’s full constellation of 258 satellites is not yet in orbit. The company has launched test satellites and is working toward operational deployment.
The timeline for global coverage depends on launch availability and regulatory approvals for the radio frequencies the system uses. For now, the record shows that LEO navigation has moved from a 1960s Navy experiment to a commercial proposition backed by modern technology.
The question is whether the infrastructure on the ground — the receivers, antennas and processing software — can keep pace with the satellites in the sky.
