Key statistics
Satellite GP-B at a glance.
Uptime
7748
Days in orbit
Revolutions
≈ 14.8
Per day
Orbit
LEO
Low Earth Orbit
Inclination
89.8
Latest
Satellite identification and parameters
Extended collection of information and parameters for GP-B.
Object identification
Identified? True
Debris? False
Object name: GP-B
International designator: 2004-014A
Object number (NORAD): 28230
Object ID (CCSDS): 28230
Country: UNITED STATES OF AMERICA (US)
Current information (Y/N): Y
RCS size: LARGE
Orbital parameters
Period: 97.133 minutes
Inclination: 89.837 deg
SMA: 6999.556 km
Apoapsis: 623.865 km
Periapsis: 618.976 km
RAAN: 57.0095 deg
Eccentricy: 0.0003492
Argument of periapsis: 89.525 deg
Mean anomaly: 270.6375 deg
Mean motion: 14.82508051 rev/day
Mean motion (dot): 0.0000057 rev/day2
B* drag term: 0.000068938 1/REarth
Two-line elements (TLE)
Creation date: July 6, 2025, 6:05 p.m.
Reference frame: TEME
Reference center: EARTH
Epoch: July 6, 2025, 2:23 p.m. UTC
TLE line 0: 0 GP-B
TLE line 1: 1 28230U 04014A 25187.59979367 .00000570 00000-0 68938-4 0 9992
TLE line 2: 2 28230 89.8370 57.0095 0003492 89.5250 270.6375 14.82508051601130
Live tracking on map
Real-time ground track for satellite GP-B.
In-orbit conjunctions
A list of the most updated potential collisions computed for object GP-B.
Associated space launch
Gravity Probe B (GP-B) was a satellite-based experiment to test two unverified predictions of general relativity: the geodetic effect and frame-dragging. This was to be accomplished by measuring, very precisely, tiny changes in the direction of spin of four gyroscopes contained in an Earth-orbiting satellite at 650 km (400 mi) altitude, crossing directly over the poles.
GP-B was lifted into orbit during the mission ‘Delta II | Gravity Probe B’, on board a Delta II space rocket.
The launch took place on April 20, 2004, 4:57 p.m. from Space Launch Complex 2W.
For more information about the launch, click the button.
Delta II | Gravity Probe B
Agency: N/A
Status: Launch Successful
Launch date: April 20, 2004, 4:57 p.m. UTC
Rocket: Delta II
Launch pad: Space Launch Complex 2W
Location: Vandenberg SFB, CA, USA
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