USA 77, 21809
Orbit data source: Space-Track
USA 77, 21809 is an American payload satellite in LEO that was launched on Fri, 08 Nov 1991 UTC via a TITAN 403A 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
Embed this page
Focus sentinelFocus sentinel
21809 intel report (Beta)
Focus sentinelFocus sentinel
Create New Watchlist
Focus sentinelFocus sentinel
Edit Public Description
Identifier
Orbit
Country
USRelated business
Manufacturer
NRL
Mission
Defense Sigint
Bus & Motor
NOSS B SSU, Unknown motor
Mass
~400 kg wet, ~400 kg dry
Launch date (UTC)
Launch vehicle
Launch site
Object type
Shape & HBR
Cyl, 0.5 m
Radar Cross Section
1.178 m², Large (>1 m²)
Expand to show TLE details & historyLast TLE update: 19 hours ago
TLE from 19 hours ago
0 USA 77
1 21809U 91076E 25319.81937591 .00003599 00000-0 30569-3 0 9998
2 21809 63.3004 6.7449 0900334 70.6090 298.9959 13.54701520 75347Epoch: 2025-11-15T19:39Z
TLE epoch observation values (Epoch: 2025-11-15T19:39:54.078Z)
Latitude
-0.00008°
Longitude
16.62649°
Altitude
781.41 km
Speed
7.601 km/s
True Right ascension
00h 26m 58s
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
11:02:40
Azimuth
Unknown
Elevation
Unknown
Doppler factor
Unknown
Orbital elements
Apogee altitude
1,722.958 km
Perigee altitude
384.707 km
Semi-major axis
7,431.97 km
Eccentricity
0.09003
Inclination
63.3004°
RAAN
6.7449°
Arg. of periapsis
70.609°
True anomaly
289.49661°
Mean anomaly
298.9959°
Eccentric anomaly
294.29418°
Mean motion
3.38756 °/min
Orbital period
106.27 mins
BSTAR
0.00030569
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 #76 in the year 1991 (1991-11-08 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.USA 77 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. |
|---|---|---|---|---|---|---|---|
| 4 mins | 2025-11-17 05:30:30.442Z | 249.474° W | 2025-11-17 05:32:30.442Z | 326.092° NNW | 32.038° | 2025-11-17 05:34:30.442Z | 14.915° NNE |
| 7 mins | 2025-11-17 12:55:30.442Z | 1.98° NNE | 2025-11-17 12:57:30.442Z | 51.838° ENE | 31.019° | 2025-11-17 13:02:30.442Z | 120.096° SE |
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 ascending 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 ascending order |
|---|