Explorer 1

Explorer 1
Explorer 1 in its orbital configuration, with the launch vehicle's fourth stage attached
NamesExplorer I
1958 Alpha 1
Mission typeEarth science
OperatorJPL / ABMA
Harvard designation1958 Alpha 1
COSPAR ID1958-001A Edit this at Wikidata
SATCAT no.00004
Mission duration120 days (planned)
111 days (achieved)
Spacecraft properties
SpacecraftExplorer I
Spacecraft typeScience Explorer
BusExplorer 1
ManufacturerJet Propulsion Laboratory
Launch mass13.97 kg (30.8 lb)
Dimensions203 cm (80 in) length
15.2 cm (6.0 in) diameter
Power60 watts
Start of mission
Launch date1 February 1958, 03:47:56 GMT
RocketJuno I (RS-29)
Launch siteAtlantic Missile Range, LC-26A
ContractorArmy Ballistic Missile Agency
Entered service1 February 1958
End of mission
Last contact23 May 1958
Decay date31 March 1970
Orbital parameters
Reference systemGeocentric orbit[1]
RegimeMedium Earth orbit
Perigee altitude358 km (222 mi)
Apogee altitude2,550 km (1,580 mi)
Inclination33.24°
Period114.80 minutes
Revolution no.58402
Instruments
Cosmic-Ray Detector
Micrometeorite Detector
Resistance Thermometers
Satellite Drag Atmospheric Density

Explorer 1 was the first satellite launched by the United States in 1958 and was part of the U.S. participation in the International Geophysical Year (IGY). The mission followed the first two satellites, both launched by the Soviet Union during the previous year, Sputnik 1 and Sputnik 2. This began a Space Race during the Cold War between the two nations.

Explorer 1 was launched on 1 February 1958 at 03:47:56 GMT (or 31 January 1958 at 22:47:56 Eastern Time) atop the first Juno I booster from LC-26A at the Cape Canaveral Missile Test Center of the Atlantic Missile Range (AMR), in Florida. It was the first spacecraft to detect the Van Allen radiation belt,[2] returning data until its batteries were exhausted after nearly four months. It remained in orbit until 1970.

Explorer 1 was given Satellite Catalog Number 00004 and the Harvard designation 1958 Alpha 1,[3] the forerunner to the modern International Designator.

  1. ^ Cite error: The named reference Trajectory was invoked but never defined (see the help page).
  2. ^ Paul Dickson, Sputnik: The Launch of the Space Race, Toronto: MacFarlane Walter & Ross, 2001, p. 190.
  3. ^ Yost, Charles W. (6 September 1963). Registration data for United States Space Launches (PDF). United Nations Office for Outer Space Affairs. Retrieved 30 July 2024.