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RADUGA 21, 18631

Orbit data source: Space-Track

RADUGA 21, 18631 is a payload satellite owned by UNKS (CIS) in GEO that was launched on Thu, 10 Dec 1987 UTC via a PROTON-K/DM-2 launch vehicle from the Tyuratam Missile And Space Complex (TTMTR). 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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<iframe src="https://www.satcat.com/sats-embedded/18631?theme=dark&initialShowStats=false" width="600" height="400" frameborder="0" title="Kayhan Space Satcat Satellite Viewer"></iframe>

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https://www.satcat.com/sats-embedded/18631?theme=dark&initialShowStats=false

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ISO8601 Format

Identifier

18631, 1987-100A

Orbit

GEO

Country

CIS

Related business

Russian Space Forces (RU)

Manufacturer

NPO PM

Mission

Non-operational Defense Communications

Bus & Motor

RADUGA, Unknown motor

Mass

1,965 kg wet, ~1,800 kg dry

Launch date (UTC)

1987-12-10 (38 years ago)

Launch vehicle

PROTON-K/DM-2

Launch site

Tyuratam Missile And Space Complex (TTMTR)

Object type

Payload

Rocket body

Debris

Shape & HBR

Cyl + 2 Pan, 4.8 m

Radar Cross Section

16.975 m², Large (>1 m²)

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Last TLE update: 15 hours ago

TLE from 15 hours ago

0 RADUGA 21
1 18631U 87100A   26091.23019352 -.00000087  00000-0  00000+0 0  9993
2 18631  11.4167 325.8091 0001352 315.5945 237.8114  1.00361187140314

Epoch: 2026-04-01T05:31Z

TLE epoch observation values (Epoch: 2026-04-01T05:31:28.720Z)

Latitude

-2.6446°

Longitude

-113.4705°

Altitude

35,764.489 km

Speed

3.075 km/s

True Right ascension

10h 35m 58s

True Declination

-2° 38' 31"

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

02:23:23

Azimuth

Unknown

Elevation

Unknown

Doppler factor

Unknown

Orbital elements

Apogee altitude

35,768.258 km

Perigee altitude

35,756.863 km

Semi-major axis

42,140.698 km

Eccentricity

0.00014

Inclination

11.4167°

RAAN

325.8091°

Arg. of periapsis

315.5945°

True anomaly

237.79829°

Mean anomaly

237.8114°

Eccentric anomaly

237.80484°

Mean motion

0.25089 °/min

Orbital period

1,434.87 mins

BSTAR

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Computing Atmospheric mass density...

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Other satellites on launch #100 in the year 1987 (1987-12-10 UTC)

SL-12 DEB *, 21620 (Decayed)

SL-12 PLAT, 18633 (Decayed)

SL-12 R/B(2), 18634

SL-12 R/B(AUX MOTOR), 18636 (Decayed)

SL-12 R/B(1), 18632 (Decayed)

SL-12 R/B(AUX MOTOR), 18635 (Decayed)

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RADUGA 21 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.
1440 mins	2026-04-01 20:42:59.396Z	196.238° SSW	2026-04-01 22:42:59.396Z	195.762° SSW	39.588°	2026-04-02 20:42:59.396Z	195.663° SSW

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18631 neighbors

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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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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

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Check out RADUGA 21, 18631 on other resources

View RADUGA 21, 18631 on NASA - NSSDCA Website

View RADUGA 21, 18631 on Heavens-Above

View RADUGA 21, 18631 on Keep Track

View RADUGA 21, 18631 on Celestrak

View RADUGA 21, 18631 on Gunter's Space Page

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

RADUGA 21, 18631

Orbit data source: Space-Track

Expand to show TLE details & historyLast TLE update: 15 hours ago

TLE from 15 hours ago

TLE epoch observation values (Epoch: 2026-04-01T05:31:28.720Z)

Visualization orbit readout

Visualization observer readout

Orbital elements

Other satellites on launch #100 in the year 1987 (1987-12-10 UTC)

RADUGA 21 Visibility forecast

18631 neighbors

Co-orbital & Co-planar RSOs

Check out RADUGA 21, 18631 on other resources

Documentation

Expand to show TLE details & history
Last TLE update: 15 hours ago