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EXPLORER 20, 870

Orbit data source: Space-Track

EXPLORER 20, 870 is a payload satellite owned by GSFC (US) in LEO that was launched on Tue, 25 Aug 1964 UTC via an SCOUT X-4 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.

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<iframe src="https://www.satcat.com/sats-embedded/870?theme=dark&initialShowStats=false" width="600" height="400" frameborder="0" title="Kayhan Space Satcat Satellite Viewer"></iframe>

Iframe URL

https://www.satcat.com/sats-embedded/870?theme=dark&initialShowStats=false

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ISO8601 Format

Identifier

870, 1964-051A

Orbit

LEO

Last TLE update

8 hours ago

Origin

National Aeronautics and Space Administration (NASA) (US)

Manufacturer

Cutler-Hammer/AIL

Mission

Civil Science

Bus & Motor

S-48, Unknown motor

Mass

44 kg wet, 44 kg dry

Launch date (UTC)

1964-08-25 (61 years ago)

Launch vehicle

SCOUT X-4

Launch site

Air Force Western Test Range (AFWTR)

Object type

Payload

Rocket body

Debris

Shape & HBR

Double Cone + 6 Rod, 18.5 m

Radar Cross Section

0.292 m², Medium (>0.1 m² and < 1m²)

Expand to show TLE details & history

TLE from 8 hours ago

0 EXPLORER 20
1 00870U 64051A   25221.60003965  .00000133  00000-0  95292-4 0  9990
2 00870  79.8954 257.8088 0097321  23.2028 337.3477 13.91701402 90096

Epoch: 2025-08-09T14:24Z

TLE epoch observation values (Epoch: 2025-08-09T14:24:03.425Z)

Latitude

0.00002°

Longitude

83.46111°

Altitude

860.023 km

Speed

7.456 km/s

True Right ascension

17h 11m 14s

True Declination

0° 00' 00"

Sunlit

Object was in daylight at epoch

Visualization orbit readout

Latitude

-11.50094°

Longitude

-94.82597°

Altitude

997.484 km

Speed

7.317 km/s

Apparent Right ascension

03h 24m 49s

Apparent Declination

-29° 17' 37"

Sunlit

Object is in daylight

Visualization observer readout

Local Sidereal Time

12:27:09

Azimuth

272.292° WNW

Elevation

-52.347°

Doppler factor

Orbital elements

Apogee altitude

990.967 km

Perigee altitude

848.916 km

Semi-major axis

7,298.079 km

Eccentricity

0.00973

Inclination

79.8954°

RAAN

257.8088°

Arg. of periapsis

23.2028°

True anomaly

336.91332°

Mean anomaly

337.3477°

Eccentric anomaly

337.131°

Mean motion

3.48121 °/min

Orbital period

103.41 mins

BSTAR

0.000095292

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Other satellites on launch #51 in the year 1964 (1964-08-25 UTC)

SCOUT X-4 R/B, 871

SCOUT X-4 DEB, 873 (Decayed)

SCOUT X-4 DEB, 874 (Decayed)

SCOUT X-4 DEB, 875 (Decayed)

SCOUT X-4 DEB, 40592 (Decayed)

EXPLORER 20 Visibility forecast

Observer location: undefined°, undefined°

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	2025-08-10 02:35:00.456Z	154.444° SSE	2025-08-10 02:40:00.456Z	89.577° E	28.859°	2025-08-10 02:44:00.456Z	34.659° NE
8 mins	2025-08-10 04:21:00.456Z	239.109° WSW	2025-08-10 04:24:00.456Z	280.433° WNW	26°	2025-08-10 04:29:00.456Z	347.845° N
9 mins	2025-08-10 13:25:00.456Z	14.385° NNE	2025-08-10 13:29:00.456Z	75.318° E	31.708°	2025-08-10 13:34:00.456Z	137.115° SSE
8 mins	2025-08-10 15:10:00.456Z	315.442° NNW	2025-08-10 15:13:00.456Z	275.006° WNW	26.839°	2025-08-10 15:18:00.456Z	213.361° SW

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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Check out EXPLORER 20, 870 on other resources

View EXPLORER 20, 870 on NASA - NSSDCA Website

View EXPLORER 20, 870 on Heavens-Above

View EXPLORER 20, 870 on Keep Track

View EXPLORER 20, 870 on Celestrak

View EXPLORER 20, 870 on Gunter's Space Page

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