Explorer 20

Explorer 20
Explorer 20 satellite
NamesIE-A
Ionospheric Explorer-A
NASA S-48
TOPSI
Topside Explorer
Mission typeIonospheric research
OperatorNASA
COSPAR ID1964-051A Edit this at Wikidata
SATCAT no.00870
Mission duration12 months (planned)
16 months (achieved)
Spacecraft properties
SpacecraftExplorer XX
Spacecraft typeIonospheric Explorer
BusIE
ManufacturerCutler-Hammer
Launch mass44.5 kg (98 lb)
PowerSolar cells and batteries
Start of mission
Launch date25 August 1964, 13:43 GMT
RocketScout X-4 (S-134R)
Launch siteVandenberg, SLC-5[1][2]
ContractorVought
Entered service25 August 1964
End of mission
Last contact20 December 1965
Orbital parameters
Reference systemGeocentric orbit
RegimeLow Earth orbit
Perigee altitude864 km (537 mi)
Apogee altitude1,025 km (637 mi)
Inclination79.90°
Period104.00 minutes
Instruments
Cosmic Noise
Fixed-Frequency Ionosonde
Spherical Ion-Mass Spectrometer
Explorer program

Explorer 20, also known Ionosphere Explorer-A, IE-A, S-48, TOPSI and Topside Explorer, was a NASA satellite launched as part of Explorer program. Its purpose was two-fold: long-term investigation of the ionosphere from above, and in situ investigation of ion concentrations and temperatures.

  1. ^ "IE". Encyclopedia Astronautica. Mark Wade. Archived from the original on 21 June 2002. Retrieved 9 June 2018.
  2. ^ "Letter dated 12 October 1964 from the Permanent Representative of the United States of America addressed to the Secretary-General" (PDF). COMMITTEE ON THE PEACEFUL USES OF OUTER SPACE. Retrieved 5 December 2022.