Key statistics
Satellite REX at a glance.
Uptime
12531
Days in orbit
Revolutions
≈ 14.2
Per day
Orbit
LEO
Low Earth Orbit
Inclination
89.5
Latest
Satellite identification and parameters
Extended collection of information and parameters for REX.
Object identification
Identified? True
Debris? False
Object name: REX
International designator: 1991-045A
Object number (NORAD): 21527
Object ID (CCSDS): 21527
Country: UNITED STATES OF AMERICA (US)
Current information (Y/N): Y
RCS size: MEDIUM
Orbital parameters
Period: 101.158 minutes
Inclination: 89.5224 deg
SMA: 7191.642 km
Apoapsis: 864.189 km
Periapsis: 762.824 km
RAAN: 273.1618 deg
Eccentricy: 0.00704741
Argument of periapsis: 55.1371 deg
Mean anomaly: 305.642 deg
Mean motion: 14.23510625 rev/day
Mean motion (dot): 0.00000262 rev/day2
B* drag term: 0.00010655838 1/REarth
Two-line elements (TLE)
Creation date: Oct. 19, 2025, 2:20 a.m.
Reference frame: TEME
Reference center: EARTH
Epoch: Oct. 18, 2025, 10:01 p.m. UTC
TLE line 0: 0 REX
TLE line 1: 1 21527U 91045A 25291.91747704 .00000262 00000-0 10656-3 0 9995
TLE line 2: 2 21527 89.5224 273.1618 0070474 55.1371 305.6420 14.23510625780779
Live tracking on map
Real-time ground track for satellite REX.
In-orbit conjunctions
A list of the most updated potential collisions computed for object REX.
Associated space launch
REX (Radiation Experiment) or ISES (Integrated Space Experiment System) was an Air Force Rome Laboratory ionospheric research satellite which tested the effects of the atmosphere on radio transmissions, and employed GPS for on-board navigation and attitude control.
REX was lifted into orbit during the mission ‘Scout G-1 | REX’, on board a Scout G-1 space rocket.
The launch took place on June 29, 1991, 2 p.m. from Space Launch Complex 5.
For more information about the launch, click the button.
Scout G-1 | REX
Agency: N/A
Status: Launch Successful
Launch date: June 29, 1991, 2 p.m. UTC
Rocket: Scout G-1
Launch pad: Space Launch Complex 5
Location: Vandenberg SFB, CA, USA
...
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