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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>

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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 (62 years ago)

Launch vehicle

SCOUT X-4

Launch site

Air Force Western Test Range (AFWTR)

Object type

Payload

Rocket body

Debris

Shape & HBR

DCONE + 6 ANT, 1.1 m

Radar Cross Section

Medium (>0.1 m² and <1 m²)

Expand to show TLE details & history
Last TLE update: 19 hours ago

TLE from 19 hours ago

0 EXPLORER 20
1   870U 64051A   26257.52572108  .00000114  00000-0  80364-4 0  9994
2   870  79.9002 181.5185 0097855  48.9730 311.9834 13.91806299145869

Epoch: 2026-09-14T12:37Z

TLE epoch observation values (Epoch: 2026-09-14T12:37:02.301Z)

Latitude

0.00006°

Longitude

-1.24584°

Altitude

877.731 km

Speed

7.437 km/s

True Right ascension

12h 06m 04s

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

00:01:53

Azimuth

Unknown

Elevation

Unknown

Doppler factor

Unknown

Orbital elements

Apogee altitude

990.986 km

Perigee altitude

848.163 km

Semi-major axis

7,297.711 km

Eccentricity

0.00979

Inclination

79.9002°

RAAN

181.5185°

Arg. of periapsis

48.973°

True anomaly

311.14302°

Mean anomaly

311.9834°

Eccentric anomaly

311.5639°

Mean motion

3.48147 °/min

Orbital period

103.4 mins

BSTAR

0.000080364

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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, 40592 (Decayed)

SCOUT X-4 DEB, 875 (Decayed)

SCOUT X-4 DEB, 874 (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.
7 mins	2026-09-15 08:12:15.537Z	308.682° NW	2026-09-15 08:15:15.537Z	276.202° WNW	17.826°	2026-09-15 08:19:15.537Z	233.75° WSW
10 mins	2026-09-15 19:47:15.537Z	186.085° SSW	2026-09-15 19:51:15.537Z	164.434° S	74.916°	2026-09-15 19:57:15.537Z	12.645° NNE
10 mins	2026-09-16 06:36:15.537Z	350.568° N	2026-09-16 06:41:15.537Z	144.733° SSE	79.677°	2026-09-16 06:46:15.537Z	168.54° 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: 19 hours ago

TLE from 19 hours ago

TLE epoch observation values (Epoch: 2026-09-14T12:37:02.301Z)

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: 19 hours ago