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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 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: 12 hours ago

TLE from 12 hours ago

0 EXPLORER 20
1 00870U 64051A   26127.26575885  .00000106  00000-0  74316-4 0  9997
2 00870  79.8972 323.2813 0097289  31.4688 329.2237 13.91783332127745

Epoch: 2026-05-07T06:22Z

TLE epoch observation values (Epoch: 2026-05-07T06:22:41.564Z)

Latitude

-0.00003°

Longitude

2.49374°

Altitude

864.364 km

Speed

7.451 km/s

True Right ascension

21h 33m 07s

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

02:23:09

Azimuth

Unknown

Elevation

Unknown

Doppler factor

Unknown

Orbital elements

Apogee altitude

990.654 km

Perigee altitude

848.655 km

Semi-major axis

7,297.792 km

Eccentricity

0.00973

Inclination

79.8972°

RAAN

323.2813°

Arg. of periapsis

31.4688°

True anomaly

328.64723°

Mean anomaly

329.2237°

Eccentric anomaly

328.93607°

Mean motion

3.48142 °/min

Orbital period

103.41 mins

BSTAR

0.000074316

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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 DEB, 40592 (Decayed)

SCOUT X-4 DEB, 875 (Decayed)

SCOUT X-4 DEB, 873 (Decayed)

SCOUT X-4 R/B, 871

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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	2026-05-08 00:12:12.073Z	4.547° NNE	2026-05-08 00:17:12.073Z	80.216° E	36.035°	2026-05-08 00:22:12.073Z	144.998° SSE
7 mins	2026-05-08 01:58:12.073Z	309.93° NW	2026-05-08 02:01:12.073Z	271.935° WNW	22.46°	2026-05-08 02:05:12.073Z	224.883° SW
9 mins	2026-05-08 13:33:12.073Z	172.659° S	2026-05-08 13:37:12.073Z	102.51° ESE	41.263°	2026-05-08 13:42:12.073Z	19.438° NNE
5 mins	2026-05-08 15:20:12.073Z	268.095° W	2026-05-08 15:22:12.073Z	292.398° WNW	16.276°	2026-05-08 15:25:12.073Z	328.029° NNW

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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: 12 hours ago

TLE from 12 hours ago

TLE epoch observation values (Epoch: 2026-05-07T06:22:41.564Z)

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: 12 hours ago