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EXPLORER 31 (ISIS-X), 1806

Orbit data source: Space-Track

EXPLORER 31 (ISIS-X), 1806 is a payload satellite owned by GSFC (US) in LEO that was launched on Mon, 29 Nov 1965 UTC via a THOR SLV-2 AGENA B 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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Identifier

1806, 1965-098B

Orbit

LEO

Country

Related business

National Aeronautics and Space Administration (NASA) (US)

Manufacturer

APL

Mission

Spacecraft

Bus & Motor

DME, Unknown motor

Mass

98 kg wet, 98 kg dry

Launch date (UTC)

1965-11-29 (60 years ago)

Launch vehicle

THOR SLV-2 AGENA B

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 31 (ISIS-X)
1 01806U 65098B   26110.81142273  .00000521  00000-0  18351-3 0  9990
2 01806  79.7853  37.1350 1422596 247.0387  97.4640 12.08319329641767

Epoch: 2026-04-20T19:28Z

TLE epoch observation values (Epoch: 2026-04-20T19:28:26.923Z)

Latitude

-0°

Longitude

-103.87338°

Altitude

1,948.059 km

Speed

6.789 km/s

True Right ascension

02h 28m 32s

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

15:52:49

Azimuth

Unknown

Elevation

Unknown

Doppler factor

Unknown

Orbital elements

Apogee altitude

2,782.106 km

Perigee altitude

500.431 km

Semi-major axis

8,019.406 km

Eccentricity

0.14226

Inclination

79.7853°

RAAN

37.135°

Arg. of periapsis

247.0387°

True anomaly

113.06794°

Mean anomaly

97.464°

Eccentric anomaly

105.32505°

Mean motion

3.02225 °/min

Orbital period

119.12 mins

BSTAR

0.00018351

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Other satellites on launch #98 in the year 1965 (1965-11-29 UTC)

THOR AGENA B DEB, 2153

ALOUETTE 2, 1804

THOR AGENA B R/B, 1807

THOR AGENA B DEB, 2092

THOR AGENA B DEB, 1948

THOR AGENA B DEB, 1951

THOR AGENA B DEB, 1808 (Decayed)

ALOUETTE 2 DEB, 25058 (Decayed)

ALOUETTE 2 DEB, 20833 (Decayed)

THOR AGENA B DEB, 1944 (Decayed)

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EXPLORER 31 (ISIS-X) 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.
18 mins	2026-04-21 17:28:30.603Z	111.99° ESE	2026-04-21 17:37:30.603Z	70.998° E	20.017°	2026-04-21 17:46:30.603Z	34.168° NE
27 mins	2026-04-21 19:23:30.603Z	174.408° S	2026-04-21 19:35:30.603Z	83.008° E	43.789°	2026-04-21 19:50:30.603Z	14.404° NNE
25 mins	2026-04-21 21:26:30.603Z	237.379° WSW	2026-04-21 21:37:30.603Z	299.953° NW	32.965°	2026-04-21 21:51:30.603Z	3.392° NNE
9 mins	2026-04-21 23:40:30.603Z	311.649° NW	2026-04-21 23:44:30.603Z	327.28° NNW	12.123°	2026-04-21 23:49:30.603Z	346.571° N
12 mins	2026-04-22 04:00:30.603Z	12.519° NNE	2026-04-22 04:06:30.603Z	41.69° NE	16.065°	2026-04-22 04:12:30.603Z	76.156° E
20 mins	2026-04-22 05:59:30.603Z	353.422° N	2026-04-22 06:11:30.603Z	77.185° E	41.15°	2026-04-22 06:19:30.603Z	150.552° SSE
16 mins	2026-04-22 08:01:30.603Z	333.9° NNW	2026-04-22 08:10:30.603Z	283.384° WNW	28.695°	2026-04-22 08:17:30.603Z	224.03° SW

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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 31 (ISIS-X), 1806 on other resources

View EXPLORER 31 (ISIS-X), 1806 on NASA - NSSDCA Website

View EXPLORER 31 (ISIS-X), 1806 on Heavens-Above

View EXPLORER 31 (ISIS-X), 1806 on Keep Track

View EXPLORER 31 (ISIS-X), 1806 on Celestrak

View EXPLORER 31 (ISIS-X), 1806 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 31 (ISIS-X), 1806

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: 2026-04-20T19:28:26.923Z)

Visualization orbit readout

Visualization observer readout

Orbital elements

Other satellites on launch #98 in the year 1965 (1965-11-29 UTC)

EXPLORER 31 (ISIS-X) Visibility forecast

Co-orbital & Co-planar RSOs

Check out EXPLORER 31 (ISIS-X), 1806 on other resources

Documentation

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