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

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ISO8601 Format

Identifier

870, 1964-051A

Orbit

LEO

Country

Related business

National Aeronautics and Space Administration (NASA) (US)

Manufacturer

Cutler-Hammer/AIL

Mission

Spacecraft

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

Unknown

Radar Cross Section

Medium (>0.1 m² and <1 m²)

Expand to show TLE details & history
Last TLE update: 13 hours ago

TLE from 13 hours ago

0 EXPLORER 20
1 00870U 64051A   25342.16171604  .00000181  00000-0  13096-3 0  9995
2 00870  79.8968 126.6293 0097313  65.9381 295.1920 13.91742302106869

Epoch: 2025-12-08T03:52Z

TLE epoch observation values (Epoch: 2025-12-08T03:52:52.265Z)

Latitude

-0.00003°

Longitude

-8.75319°

Altitude

895.683 km

Speed

7.419 km/s

True Right ascension

08h 26m 31s

True Declination

0° 00' 00"

Sunlit

Object was in full shadow 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

15:22:52

Azimuth

Unknown

Elevation

Unknown

Doppler factor

Unknown

Orbital elements

Apogee altitude

990.817 km

Perigee altitude

848.78 km

Semi-major axis

7,297.935 km

Eccentricity

0.00973

Inclination

79.8968°

RAAN

126.6293°

Arg. of periapsis

65.9381°

True anomaly

294.17774°

Mean anomaly

295.192°

Eccentric anomaly

294.68539°

Mean motion

3.48131 °/min

Orbital period

103.41 mins

BSTAR

0.00013096

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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, 875 (Decayed)

SCOUT X-4 DEB, 873 (Decayed)

SCOUT X-4 DEB, 874 (Decayed)

SCOUT X-4 DEB, 40592 (Decayed)

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You can import UDL-sourced sensor .json files into the Sandbox to generate a visibility chart that accounts for multi-vendor sensor geometry.

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EXPLORER 20 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.
6 mins	2025-12-08 19:59:29.895Z	32.854° NE	2025-12-08 20:02:29.895Z	65.427° ENE	14.477°	2025-12-08 20:05:29.895Z	96.793° ESE
10 mins	2025-12-08 21:43:29.895Z	343.62° N	2025-12-08 21:47:29.895Z	272.897° WNW	44.055°	2025-12-08 21:53:29.895Z	177.167° S
6 mins	2025-12-09 09:21:29.895Z	117.826° SE	2025-12-09 09:23:29.895Z	93.637° ESE	17.257°	2025-12-09 09:27:29.895Z	47.209° ENE
9 mins	2025-12-09 11:04:29.895Z	215.022° SW	2025-12-09 11:08:29.895Z	302.136° NW	38.272°	2025-12-09 11:13:29.895Z	1.614° NNE

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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 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.

EXPLORER 20, 870

Orbit data source: Space-Track

Expand to show TLE details & historyLast TLE update: 13 hours ago

TLE from 13 hours ago

TLE epoch observation values (Epoch: 2025-12-08T03:52:52.265Z)

Visualization orbit readout

Visualization observer readout

Orbital elements

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

EXPLORER 20 Visibility forecast

Co-orbital & Co-planar RSOs

Check out EXPLORER 20, 870 on other resources

Documentation

Expand to show TLE details & history
Last TLE update: 13 hours ago