GPS III SV01

About This Satellite

NAVSTAR 77, or USA 289, is the first GPS III spacecraft, SV01. Nicknamed Vespucci, it launched on December 23, 2018, on a Falcon 9 from Cape Canaveral. It marked the beginning of another GPS spacecraft generation, not the replacement of the entire constellation in one launch.

Vespucci had to climb before joining the constellation

The launch announcement reported command reception after separation, followed by plans for orbit raising, antenna and solar-array deployment, and payload testing. Reaching a transfer orbit and entering navigation service are different milestones. A launch-era orbit should therefore not be mistaken for the intended medium Earth orbit of the completed checkout phase.

Generation numbers are not accuracy ratings

GPS III describes the spacecraft generation. It does not mean a receiver gets three times the accuracy merely by tracking this object. User performance also depends on the other available satellites, signal reception, corrections, and receiver processing. This page identifies the platform; it does not measure a positioning solution.

Mission reference: Lockheed Martin: GPS III SV01 launch and checkout. Editorial review: 2026-09-07.

L1C and L1 C/A are different signals

GPS III introduced L1C, a civil signal designed for interoperability with other navigation systems. L1C shares the L1 frequency with the older C/A signal but uses a different signal design. The older signal was retained for compatibility. The archived GPS.gov description explains that distinction; it should not be used as a live signal-health bulletin.

Reference: GPS.gov archive: L1C design and backwards compatibility.

Designed for a longer working life

The manufacturer specified a 15-year design life for GPS III. Design life is an engineering target, not a guaranteed retirement date or evidence that every payload remains healthy. For this first vehicle, the documented launch and checkout sequence provides a firm historical anchor without extrapolating a future end of service.

Reference: Lockheed Martin: GPS III design life and first-flight milestones.

Reading this orbital snapshot

Based on TLE epoch: 2026-09-05. Estimated altitude ranges from 20,077 km at perigee to 20,288 km at apogee, a difference of 211 km. The orbital period is about 718.0 minutes. Eccentricity 0.00397 indicates a nearly circular path. In a two-body approximation, perigee speed is 1.01 times apogee speed. These are mean-element estimates, not instantaneous measurements. Distance per orbit uses an ellipse approximation.

Saved build snapshot. If a valid TLE is retrieved, this explanation and the orbit panel update together. Otherwise this dated snapshot is retained.

Ground track is not sensor coverage

An inclination of 55.73 degrees implies approximate geocentric ground-track limits of 55.7 degrees north and south. This is a prograde orbit, moving in the same general direction as Earth rotation. The plotted line marks the point beneath the object. It does not represent camera coverage, radio reception, or a guaranteed visible pass.

Accuracy and missing information

The introductory record describes the build snapshot. The orbital snapshot explanation and orbit panel share any successfully retrieved TLE; check the displayed epoch. Reentered objects retain historical data only. Mission history is not rewritten by TLE updates. TLE/SGP4 positions are predictions and can change after maneuvers or updated observations. The 14-day stale-data cutoff is a display safeguard, not an accuracy guarantee. Local passes are geometric predictions, not a visibility forecast. No verified operator or mission status means unknown, not active. Do not use this catalog for collision avoidance or operational flight decisions.

Catalog sources: CelesTrak SATCAT: NORAD 43873 · GCAT: S43873 (source update 2026 Sep 4 2345:57). Supplementary metadata: SatNOGS DB, retrieved 2026-09-05T12:57:25.375Z. Page assembled 2026-09-15. GCAT phase codes describe trajectory phases, not mission health.

Learn more: TLE data · Perigee and apogee · Ground tracks · JOT (Jewawud Live Orbital Map)

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