COSMOS 2129, 21104
Orbit data source: Space-Track
COSMOS 2129, 21104 is a payload satellite owned by UNKS RF (CIS) in LEO that was launched on Tue, 12 Feb 1991 UTC via a KOSMOS 11K65M launch vehicle from the Plesetsk Missile And Space Complex (PKMTR). 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
21104 intel report (Beta)
Focus sentinelFocus sentinel
Edit Public Description
Focus sentinelFocus sentinel
Edit Sat Name
Focus sentinelFocus sentinel
Create New Watchlist
Identifier
Orbit
Country
CISRelated business
Manufacturer
NPO PM
Mission
Defense Communications
Bus & Motor
STRELA-1 11F625, Unknown motor
Mass
60 kg wet, 60 kg dry
Launch date (UTC)
Launch vehicle
Launch site
Object type
Shape & HBR
Sphere, 0.4 m
Radar Cross Section
0.588 m², Medium (>0.1 m² and < 1m²)
Expand to show TLE details & historyLast TLE update: 2 days ago
TLE from 2 days ago
0 COSMOS 2129
1 21104U 91009E 26171.48093847 -.00000026 00000-0 -60812-4 0 9998
2 21104 74.0274 194.9125 0024933 3.5046 70.9888 12.53744095617930Epoch: 2026-06-20T11:32Z
TLE epoch observation values (Epoch: 2026-06-20T11:32:33.083Z)
Latitude
68.14944°
Longitude
158.33765°
Altitude
1,453.994 km
Speed
7.144 km/s
True Right ascension
16h 00m 40s
True Declination
68° 02' 27"
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
08:32:04
Azimuth
Unknown
Elevation
Unknown
Doppler factor
Unknown
Orbital elements
Apogee altitude
1,466.214 km
Perigee altitude
1,427.195 km
Semi-major axis
7,824.841 km
Eccentricity
0.00249
Inclination
74.0274°
RAAN
194.9125°
Arg. of periapsis
3.5046°
True anomaly
71.2592°
Mean anomaly
70.9888°
Eccentric anomaly
71.12397°
Mean motion
3.13567 °/min
Orbital period
114.81 mins
BSTAR
-0.000060812
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 #9 in the year 1991 (1991-02-12 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.COSMOS 2129 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. |
|---|---|---|---|---|---|---|---|
| 9 mins | 2026-06-23 00:33:14.676Z | 121.103° SE | 2026-06-23 00:37:14.676Z | 92.128° ESE | 15.274° | 2026-06-23 00:42:14.676Z | 55.489° ENE |
| 15 mins | 2026-06-23 02:26:14.676Z | 195.06° SSW | 2026-06-23 02:33:14.676Z | 169.665° S | 44.859° | 2026-06-23 02:41:14.676Z | 19.762° NNE |
| 10 mins | 2026-06-23 04:27:14.676Z | 270.562° WNW | 2026-06-23 04:32:14.676Z | 312.137° NW | 20.162° | 2026-06-23 04:37:14.676Z | 351.494° N |
| 11 mins | 2026-06-23 10:35:14.676Z | 10.811° NNE | 2026-06-23 10:40:14.676Z | 50.108° ENE | 19.255° | 2026-06-23 10:46:14.676Z | 94.747° ESE |
| 16 mins | 2026-06-23 12:31:14.676Z | 341.736° N | 2026-06-23 12:38:14.676Z | 1.374° NNE | 44.681° | 2026-06-23 12:47:14.676Z | 161.918° S |
| 8 mins | 2026-06-23 14:31:14.676Z | 297.729° NW | 2026-06-23 14:35:14.676Z | 266.116° W | 17.167° | 2026-06-23 14:39:14.676Z | 236.508° WSW |
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 |
|---|