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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: 6 hours ago

TLE from 6 hours ago

0 EXPLORER 20
1   870U 64051A   26037.04532872  .00000154  00000-0  11173-3 0  9996
2   870  79.8955  61.4611 0096080 268.2531  90.7618 13.91761660115197

Epoch: 2026-02-06T01:05Z

TLE epoch observation values (Epoch: 2026-02-06T01:05:16.401Z)

Latitude

-0.00008°

Longitude

-91.04609°

Altitude

926.899 km

Speed

7.388 km/s

True Right ascension

04h 05m 50s

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

09:12:47

Azimuth

Unknown

Elevation

Unknown

Doppler factor

Unknown

Orbital elements

Apogee altitude

989.849 km

Perigee altitude

849.613 km

Semi-major axis

7,297.868 km

Eccentricity

0.00961

Inclination

79.8955°

RAAN

61.4611°

Arg. of periapsis

268.2531°

True anomaly

91.86245°

Mean anomaly

90.7618°

Eccentric anomaly

91.31215°

Mean motion

3.48136 °/min

Orbital period

103.41 mins

BSTAR

0.00011173

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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)

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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.
8 mins	2026-02-06 12:01:31.358Z	19.909° NNE	2026-02-06 12:05:31.358Z	63.709° ENE	21.188°	2026-02-06 12:09:31.358Z	110.265° ESE
10 mins	2026-02-06 13:46:31.358Z	334.008° NNW	2026-02-06 13:50:31.358Z	271.929° WNW	39.009°	2026-02-06 13:56:31.358Z	189.391° SSW
8 mins	2026-02-07 01:22:31.358Z	136.055° SSE	2026-02-07 01:26:31.358Z	81.594° E	25.583°	2026-02-07 01:30:31.358Z	37.15° NE
9 mins	2026-02-07 03:06:31.358Z	227.573° WSW	2026-02-07 03:10:31.358Z	289.963° WNW	33.431°	2026-02-07 03:15:31.358Z	353.926° N

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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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Click to sort rows by RSO header in ascending order	Click to sort rows by Country header in ascending order	Click to sort rows by Type header in ascending order	Click to sort rows by Inclination Δ header in ascending order	Click to sort rows by RAAN Δ header in ascending order	Click to sort rows by Coplanar Angle header in ascending order	Click to sort rows by SMA Δ header in ascending order	Click to sort rows by Orbital period header in ascending order	Click to sort rows by <5km Md TCA header in descending order

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: 2026-02-06T01:05:16.401Z)

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