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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

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 (62 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: 6 hours ago

TLE from 6 hours ago

0 EXPLORER 20
1   870U 64051A   26099.15760196  .00000126  00000-0  89197-4 0  9999
2   870  79.9013 353.8695 0097517 104.8229 256.3754 13.91777371123835

Epoch: 2026-04-09T03:46Z

TLE epoch observation values (Epoch: 2026-04-09T03:46:56.809Z)

Latitude

-0.00007°

Longitude

99.72314°

Altitude

942.665 km

Speed

7.372 km/s

True Right ascension

23h 35m 28s

True Declination

0° 00' 00"

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

16:16:55

Azimuth

Unknown

Elevation

Unknown

Doppler factor

Unknown

Orbital elements

Apogee altitude

990.842 km

Perigee altitude

848.509 km

Semi-major axis

7,297.813 km

Eccentricity

0.00975

Inclination

79.9013°

RAAN

353.8695°

Arg. of periapsis

104.8229°

True anomaly

255.29256°

Mean anomaly

256.3754°

Eccentric anomaly

255.83366°

Mean motion

3.4814 °/min

Orbital period

103.41 mins

BSTAR

0.000089197

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

SCOUT X-4 DEB, 874 (Decayed)

SCOUT X-4 R/B, 871

SCOUT X-4 DEB, 875 (Decayed)

SCOUT X-4 DEB, 40592 (Decayed)

SCOUT X-4 DEB, 873 (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.
10 mins	2026-04-09 17:41:42.967Z	182.473° SSW	2026-04-09 17:46:42.967Z	91.469° ESE	44.173°	2026-04-09 17:51:42.967Z	14.875° NNE
4 mins	2026-04-09 19:30:42.967Z	282.712° WNW	2026-04-09 19:31:42.967Z	294.156° NW	14.013°	2026-04-09 19:34:42.967Z	326.782° NNW
9 mins	2026-04-10 04:31:42.967Z	353.857° N	2026-04-10 04:35:42.967Z	86.11° E	44.341°	2026-04-10 04:40:42.967Z	164.703° S

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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: 6 hours ago

TLE from 6 hours ago

TLE epoch observation values (Epoch: 2026-04-09T03:46:56.809Z)

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: 6 hours ago