GREB, 731
Orbit data source: Space-Track
GREB, 731 is an American payload satellite in LEO that was launched on Sat, 11 Jan 1964 UTC via a THOR SLV-2A AGENA D launch vehicle from the Air Force Western Test Range (AFWTR). Payload-class satellites include a variety of spacecraft equipped with specific instruments for various scientific and technological missions. These include communications satellites like Starlink; space stations such as the ISS; scientific satellites like the Hubble; Earth observation satellites from companies like Planet Labs, Umbra, and HawkEye 360; GPS; miniature CubeSats for education and research; and military/defense satellites.
Focus sentinelFocus sentinel
Request partner network tasking
Focus sentinelFocus sentinel
Embed this page
Focus sentinelFocus sentinel
731 intel report (Beta)
Focus sentinelFocus sentinel
Create New Watchlist
Focus sentinelFocus sentinel
Edit Public Description
Identifier
Orbit
Country
USRelated business
Manufacturer
NRL
Mission
Spacecraft
Bus & Motor
NRL 20", Unknown motor
Mass
29 kg wet, 29 kg dry
Launch date (UTC)
Launch vehicle
Launch site
Object type
Shape & HBR
Unknown
Radar Cross Section
Medium (>0.1 m² and <1 m²)
Expand to show TLE details & historyLast TLE update: 9 hours ago
TLE from 9 hours ago
0 GREB
1 00731U 64001E 26009.10797913 .00000025 00000-0 57209-4 0 9990
2 00731 69.9049 248.8553 0016394 238.8123 121.1375 13.96281122155371Epoch: 2026-01-09T02:35Z
TLE epoch observation values (Epoch: 2026-01-09T02:35:29.396Z)
Latitude
-0.00009°
Longitude
101.33032°
Altitude
915.198 km
Speed
7.392 km/s
True Right ascension
16h 35m 25s
True Declination
0° 00' 00"
Sunlit
Visualization orbit readout
Latitude
Unknown
Longitude
Unknown
Altitude
Unknown
Speed
Unknown
Apparent Right ascension
Unknown
Apparent Declination
Unknown
Sunlit
Visualization observer readout
Local Sidereal Time
11:36:23
Azimuth
Unknown
Elevation
Unknown
Doppler factor
Unknown
Orbital elements
Apogee altitude
916.694 km
Perigee altitude
892.815 km
Semi-major axis
7,282.891 km
Eccentricity
0.00164
Inclination
69.9049°
RAAN
248.8553°
Arg. of periapsis
238.8123°
True anomaly
121.29813°
Mean anomaly
121.1375°
Eccentric anomaly
121.21783°
Mean motion
3.49211 °/min
Orbital period
103.09 mins
BSTAR
0.000057209
Loading maneuver chart data...
Computing Atmospheric mass density...
Loading historical data...
Loading historical data...
Loading historical data...
Loading historical data...
Loading historical data...
Loading historical data...
Loading historical data...
Other satellites on launch #1 in the year 1964 (1964-01-11 UTC)
Did you know?
You can import UDL-sourced sensor .json files into the Sandbox to generate a visibility chart that accounts for multi-vendor sensor geometry.GREB Visibility forecast
Loading observer location...
Span | Click to sort rows by Start time (UTC) header in descending order | Start Az. | Max El. time (UTC) | Max El. Az. | Max El. | End time (UTC) | End Az. |
|---|---|---|---|---|---|---|---|
| 10 mins | 2026-01-09 16:26:49.228Z | 168.084° S | 2026-01-09 16:31:49.228Z | 111.557° ESE | 29.427° | 2026-01-09 16:36:49.228Z | 45.607° ENE |
| 9 mins | 2026-01-09 18:13:49.228Z | 245.859° WSW | 2026-01-09 18:17:49.228Z | 306.495° NW | 30.874° | 2026-01-09 18:22:49.228Z | 7.878° NNE |
| 8 mins | 2026-01-10 01:29:49.228Z | 8.141° NNE | 2026-01-10 01:33:49.228Z | 57.352° ENE | 20.924° | 2026-01-10 01:37:49.228Z | 100.704° ESE |
| 10 mins | 2026-01-10 03:14:49.228Z | 325.692° NNW | 2026-01-10 03:19:49.228Z | 231.793° WSW | 40.846° | 2026-01-10 03:24:49.228Z | 172.126° S |
Co-orbital & Co-planar RSOs
Thresholds — Semi-major Axis: ±100 km, RAAN: ±3°, Inclination: ±5°
TCA is derived from TLE conjunctions
Click to sort rows by RSO header in ascending order | Click to sort rows by Country header in ascending order | Click to sort rows by Type header in ascending order | Click to sort rows by Inclination Δ header in ascending order | Click to sort rows by RAAN Δ header in ascending order | Click to sort rows by Coplanar Angle header in ascending order | Click to sort rows by SMA Δ header in ascending order | Click to sort rows by Orbital period header in ascending order | Click to sort rows by <5km Md TCA header in descending order |
|---|
CAUTION: Conjunctions in this section are generated from low-fidelity TLE screenings
Authenticating...
Click to sort rows by Secondary header in ascending order | Click to sort rows by Secondary name header in ascending order | Click to sort rows by Country header in ascending order | Click to sort rows by Owner header in ascending order | Click to sort rows by Obj. Type header in ascending order | Click to sort rows by Miss dist. header in ascending order | Click to sort rows by Rel. speed header in ascending order | Click to sort rows by Apr. angle header in ascending order | Click to sort rows by TCA header in descending order |
|---|