Explorer 2

Explorer 2

Launch of Explorer 2 satellite
Names	Explorer II
Mission type	Earth science
Operator	JPL / Army Ballistic Missile Agency
Mission duration	Failed to orbit 120 days (planned)
Spacecraft properties
Spacecraft	Explorer II
Spacecraft type	Science Explorer
Bus	Explorer 1
Manufacturer	Jet Propulsion Laboratory
Launch mass	14.22 kg (31.3 lb)
Dimensions	203 cm (80 in) length 15.2 cm (6.0 in) diameter
Power	60 watts
Start of mission
Launch date	5 March 1958, 18:27:57 GMT[1]
Rocket	Juno I (RS-26)
Launch site	Atlantic Missile Range, LC-26A
Contractor	Army Ballistic Missile Agency
End of mission
Destroyed	Failed to orbit
Orbital parameters
Reference system	Geocentric orbit (planned) [2]
Regime	Medium Earth orbit
Perigee altitude	358 km (222 mi)
Apogee altitude	2,550 km (1,580 mi)
Inclination	32.24°
Period	114.80 minutes
Instruments
Geiger counter Micrometeorite Detector Satellite Drag Atmospheric Density Resistance Thermometers Thermometers
Explorer program ← Explorer 1 Explorer 3 →

Explorer 2 was an American unmanned space mission within the Explorer program. Intended to be a repetition of the previous Explorer 1 mission, which placed a satellite into medium Earth orbit, the spacecraft was unable to reach orbit due to a failure in the launch vehicle during launch.

Explorer 2 was launched from Cape Canaveral Missile Test Center of the Atlantic Missile Range (AMR), LC-26A in Florida on 5 March 1958 at 18:27:57 GMT by a Juno I launch vehicle.^[3] The Juno I had its origins in the United States Army's Project Orbiter in 1954. The project was canceled in 1955 when the decision was made to proceed with Project Vanguard.