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COSMOS 2125, 21100

Orbit data source: Space-Track

COSMOS 2125, 21100 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.

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https://www.satcat.com/sats-embedded/21100?theme=dark&initialShowStats=false

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Identifier

21100, 1991-009A

Orbit

LEO

Country

CIS

Related business

Russian Space Forces (RU)

Manufacturer

NPO PM

Mission

Defense Communications

Bus & Motor

STRELA-1 11F625, Unknown motor

Mass

60 kg wet, 60 kg dry

Launch date (UTC)

1991-02-12 (35 years ago)

Launch vehicle

KOSMOS 11K65M

Launch site

Plesetsk Missile And Space Complex (PKMTR)

Object type

Payload

Rocket body

Debris

Shape & HBR

Sphere, Unknown HBR

Radar Cross Section

0.588 m², Medium (>0.1 m² and < 1m²)

Expand to show TLE details & history
Last TLE update: 10 hours ago

TLE from 10 hours ago

0 COSMOS 2125
1 21100U 91009A   26071.18027257 -.00000006  00000-0  66040-4 0  9998
2 21100  74.0265  89.3413 0010136 339.2255  86.5296 12.49965291600615

Epoch: 2026-03-12T04:19Z

TLE epoch observation values (Epoch: 2026-03-12T04:19:35.550Z)

Latitude

61.42404°

Longitude

-113.85989°

Altitude

1,474.295 km

Speed

7.132 km/s

True Right ascension

08h 03m 29s

True Declination

61° 17' 33"

Sunlit

Object was in daylight at epoch

Visualization orbit readout

Latitude

Unknown

Longitude

Unknown

Altitude

Unknown

Speed

Unknown

Apparent Right ascension

Unknown

Apparent Declination

Unknown

Sunlit

N/A

Visualization observer readout

Local Sidereal Time

18:19:13

Azimuth

Unknown

Elevation

Unknown

Doppler factor

Unknown

Orbital elements

Apogee altitude

1,470.423 km

Perigee altitude

1,454.528 km

Semi-major axis

7,840.612 km

Eccentricity

0.00101

Inclination

74.0265°

RAAN

89.3413°

Arg. of periapsis

339.2255°

True anomaly

86.64555°

Mean anomaly

86.5296°

Eccentric anomaly

86.58757°

Mean motion

3.12621 °/min

Orbital period

115.16 mins

BSTAR

0.00006604

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Other satellites on launch #9 in the year 1991 (1991-02-12 UTC)

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COSMOS 2125 Visibility forecast

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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.
12 mins	2026-03-12 14:13:46.556Z	314.682° NW	2026-03-12 14:19:46.556Z	270.395° WNW	21.048°	2026-03-12 14:25:46.556Z	223.959° SW
13 mins	2026-03-13 01:12:46.556Z	153.288° SSE	2026-03-13 01:18:46.556Z	95.825° ESE	31.198°	2026-03-13 01:25:46.556Z	36.283° NE
15 mins	2026-03-13 03:08:46.556Z	226.15° WSW	2026-03-13 03:15:46.556Z	292.067° WNW	36.823°	2026-03-13 03:23:46.556Z	8.453° NNE
14 mins	2026-03-13 11:18:46.556Z	359.837° N	2026-03-13 11:24:46.556Z	57.616° ENE	32.941°	2026-03-13 11:32:46.556Z	127.822° SE
14 mins	2026-03-13 13:15:46.556Z	326.08° NNW	2026-03-13 13:22:46.556Z	257.565° W	35.804°	2026-03-13 13:29:46.556Z	193.933° SSW

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Co-orbital & Co-planar RSOs

Thresholds — Semi-major Axis: ±100 km, RAAN: ±3°, Inclination: ±5°
TCA is derived from TLE conjunctions

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CAUTION: Conjunctions in this section are generated from low-fidelity TLE screenings

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Check out COSMOS 2125, 21100 on other resources

View COSMOS 2125, 21100 on NASA - NSSDCA Website

View COSMOS 2125, 21100 on Heavens-Above

View COSMOS 2125, 21100 on Keep Track

View COSMOS 2125, 21100 on Celestrak

View COSMOS 2125, 21100 on Gunter's Space Page

Satcat and Kayhan Space are not affiliated with NASA, Celestrak, Heavens-Above, Keep Track, or Gunter's Space Page.

COSMOS 2125, 21100

Orbit data source: Space-Track

Expand to show TLE details & historyLast TLE update: 10 hours ago

TLE from 10 hours ago

TLE epoch observation values (Epoch: 2026-03-12T04:19:35.550Z)

Visualization orbit readout

Visualization observer readout

Orbital elements

Other satellites on launch #9 in the year 1991 (1991-02-12 UTC)

COSMOS 2125 Visibility forecast

Co-orbital & Co-planar RSOs

Check out COSMOS 2125, 21100 on other resources

Documentation

Expand to show TLE details & history
Last TLE update: 10 hours ago