Explorer 31

Explorer 31
Explorer 31 satellite
NamesDME-A
Direct Measurement Explorer-A
Mission typeEarth science
OperatorNASA
COSPAR ID1965-098B Edit this at Wikidata
SATCAT no.01806
Spacecraft properties
SpacecraftExplorer XXXI
Spacecraft typeDirect Measurement Explorer
BusDME
Launch mass98.9 kg (218 lb)
Start of mission
Launch date29 November 1965, 04:48:47 GMT[1]
RocketThor SLV-2 Agena B (Thor 453 / Agena 6102 (TA5))
Launch siteVandenberg, SLC-2E
ContractorDouglas Aircraft Company / Lockheed Corporation
Entered service29 November 1965
Orbital parameters
Reference systemGeocentric orbit[2]
RegimeLow Earth orbit
Perigee altitude505 km (314 mi)
Apogee altitude2,978 km (1,850 mi)
Inclination79.80°
Period121.40 minutes
Instruments
Cylindrical Electrostatic Probes
Electron Temperature
Energetic Electron Current Monitor
Ion Mass Spectrometer
Magnetic Ion-Mass Spectrometer
Thermal Electron Probe
Thermal Ion Probe
Explorer program

Explorer 31, also called DME-A, was a NASA satellite launched as part of the Explorer program. Explorer 31 was launched on 29 November 1965 from Vandenberg Air Force Base, California, with a Thor-Agena launch vehicle. Explorer 31 was released along with the Canadian satellite Alouette 2.[3]

Explorer 31 was a small ionospheric observatory instrumented to make direct measurements of selected ionospheric parameters at the spacecraft. Since the spacecraft had no tape recorder, data could be observed at the spacecraft only when the spacecraft was in sight of the telemetry station and when commanded on. Experiments were operated either simultaneously or sequentially, as desired. The satellite was spin-stabilized with the spin axis perpendicular to the orbit plane. The spin rate and spin axis were controlled by an onboard magnetic torquing system. The attitude and spin rate information were observed by a Sun sensor and a three-axis magnetometer.[3]

Satellite performance was satisfactory except for a partial power failure in May 1966, which reduced data acquisition time to about half the nominal amount. Some difficulties were encountered in obtaining attitude information that was necessary for the reduction of the experiment observations. On July 1, 1969, the satellite data observations were terminated with five of the seven experiments operating. Responsibility for standby monitoring of the satellite was given to the ESSA telemetry station at Boulder, Colorado, on July 8, 1969. During this standby operation, experiment data were collected only once on 1 October 1969, for 9 minutes from the electrostatic probe for use in studying a red arc event. On January 15, 1971, no response was received from a variety of satellite commands, and the satellite was abandoned.[3]

  1. ^ "Launch Log". Jonathan's Space Report. 21 July 2021. Retrieved 9 November 2021.
  2. ^ "Trajectory: Explorer 31 (DME-A) 1965-098B". NASA. 28 October 2021. Retrieved 9 November 2021. Public Domain This article incorporates text from this source, which is in the public domain.
  3. ^ a b c "Display: Explorer 31 (DME-A) 1965-098B". NASA. 28 October 2021. Retrieved 9 November 2021. Public Domain This article incorporates text from this source, which is in the public domain.