Explorer II

Organization:	Army Ballistic Missile Agency
Major Contractors:	Jet Propulsion Laboratory
Mission Type:	Earth Science
Satellite of:	Earth
Launch:	March 5, 1958 - Failed to orbit
Launch Vehicle:	Jupiter-C 4th stage did not ignite
Decay:	March 5, 1958
Mission Duration:	0 days
Mass:	14.52 kg (8.5 kg instruments)
NSSDC ID:	none
Webpage:	NASA NSSDC Master Catalog
Orbital elements
Semimajor Axis:	0 km
Eccentricity:	.0
Inclination:	0°
Orbital Period:	0 minutes
Apogee:	0 km
Perigee:	0 km
Orbits:	0
Instruments
Geiger-Mueller detector :	Detection of cosmic rays
Wire grid array :	Micrometeorite detection
Acoustic detector :	Micrometeorite detection

Explorer 1 - Americas first satellite (NASA illustration) This image has been released into the public domain by the copyright holder, its copyright has expired, or it is ineligible for copyright. ... The Army Ballistic Missile Agency (ABMA) is the part of the US Army which, in the 1950s, designed the Jupiter-C IRBM and Jupiter IRBM. The Saturn I was also conceived by the ABMA. At this time the ABMA was headed by Doctor Wernher von Braun. ... The Caltech Jet Propulsion Laboratory (JPL), in La Cañada Flintridge, near Pasadena, California, USA, builds and operates unmanned spacecraft for the National Aeronautics and Space Administration (NASA). ... ... Earth, also known as Terra, and Tellus mostly in the 19th century, is the third-closest planet to the Sun. ... March 5 is the 64th day of the year in the Gregorian Calendar (65th in leap years). ... 1958 (MCMLVIII) was a common year starting on Wednesday of the Gregorian calendar. ... The Jupiter-C Intermediate Range Ballistic Missile (IRBM) was designed by the Army Ballistic Missile Agency (ABMA) The vehicle consists of a modified Redstone ballistic missile with three solid-propellant upper stages. ... March 5 is the 64th day of the year in the Gregorian Calendar (65th in leap years). ... 1958 (MCMLVIII) was a common year starting on Wednesday of the Gregorian calendar. ... Mass is a property of physical objects that, roughly speaking, measures the amount of matter they contain. ... The elements of an orbit are the parameters needed to specify that orbit uniquely, given a model of two ideal masses obeying the Newtonian laws of motion and the inverse-square law of gravitational attraction. ... In geometry, the semi-major axis (also semimajor axis) a applies to ellipses and hyperbolas. ... In astrodynamics, under standard assumptions any orbit must be of conic section shape. ... Inclination is one of the six orbital parameters describing the shape and orientation of a celestial orbit and is the angular distance of the orbital plane from the plane of the reference (usually planets equator or the ecliptic), stated in degrees. ...

Mission Description

Explorer-II was to be a repeat of the Explorer I mission. However, there was a launch failure in the Jupiter-C rocket and Explorer II did not reach orbit. Explorer-I, officially known as Satellite 1958 Alpha, was the first United States Earth satellite and was sent aloft as part of the United States program for the International Geophysical Year 1957-1958. ... The Jupiter-C Intermediate Range Ballistic Missile (IRBM) was designed by the Army Ballistic Missile Agency (ABMA) The vehicle consists of a modified Redstone ballistic missile with three solid-propellant upper stages. ...

The satellite was launched from Cape Canaveral (now Kennedy Space Center) in Florida on March 5, 1958, by a Jupiter-C launch vehicle. Cape Canaveral from space, August 1991 Cape Canaveral (Cabo Cañaveral in Spanish) is a strip of land in Brevard County, Florida, United States, near the center of that states Atlantic coast. ... Merritt Island and Kennedy Space Center The John F. Kennedy Space Center (KSC) is the NASA space vehicle launch facility (spaceport) at Cape Canaveral on Merritt Island in Florida, United States. ... State nickname: Sunshine State Official languages English Capital Tallahassee Largest city Jacksonville Governor Jeb Bush (R) Senators Bill Nelson (D) Mel Martinez (R) Area  - Total  - % water Ranked 22nd 170,451 km² 17. ... March 5 is the 64th day of the year in the Gregorian Calendar (65th in leap years). ... 1958 (MCMLVIII) was a common year starting on Wednesday of the Gregorian calendar. ... The Jupiter-C Intermediate Range Ballistic Missile (IRBM) was designed by the Army Ballistic Missile Agency (ABMA) The vehicle consists of a modified Redstone ballistic missile with three solid-propellant upper stages. ...

The Jupiter-C has its origins in the United States Army's Project Orbiter in 1954. The project was canceled in 1955, however, when the decision was made to proceed with Project Vanguard. The Jupiter-C Intermediate Range Ballistic Missile (IRBM) was designed by the Army Ballistic Missile Agency (ABMA) The vehicle consists of a modified Redstone ballistic missile with three solid-propellant upper stages. ... Project Orbiter was a proposed spacecraft, an early competitor to Project Vanguard. ... 1954 (MCMLIV) was a common year starting on Friday of the Gregorian calendar. ... 1955 (MCMLV) was a common year starting on Saturday of the Gregorian calendar. ... Project Vanguard was the name of the United States program that was to have launched the first artificial satellite of the Earth. ...

Following the launch of the Soviet Sputnik I on October 4, 1957, ABMA was directed to proceed with the launching of a satellite using the Jupiter-C, which had already been flight-tested in nose-cone re-entry tests for the Jupiter IRBM (intermediate-range ballistic missile). Working closely together, ABMA and JPL completed the job of modifying the Jupiter-C and building the Explorer-I in 84 days. Sputnik 1 was the first artificial satellite to be launched into orbit, on October 4, 1957. ... October 4 is the 277th day of the year (278th in Leap years). ... 1957 (MCMLVII) was a common year starting on Tuesday of the Gregorian calendar. ... Jupiter IRBM mobile missile The Jupiter Intermediate Range Ballistic Missile, first tested in 1957, was the United States second Intermediate-range ballistic missile (IRBM). ... An intermediate-range ballistic missile, or IRBM, is a ballistic missile with a range of 2750-5500 km or 1719-3437 miles. ...

Spacecraft Design

Explorer II was equipped with a geiger counter for the purposes of detecting cosmic rays. After Explorer III, it was decided that the original geiger counter had been overwhelmed by strong radiation coming from a belt of charged particles trapped in space by the Earth's magnetic field. (see: Van Allen radiation belt) Image:A Geiger counter. ... Cosmic rays can loosely be defined as energetic particles originating outside of the Earth. ... Mission Description Explorer-III was nearly identical to Explorer I in design and mission. ... This article does not cite its references or sources. ... Van Allen radiation belts The Van Allen radiation belt is a torus of energetic charged particles (ie. ...

Mission Results

Explorer II failed to reach orbit due to Jupiter-C launch vehicle malfunction. Attempted orbit of Explorer-II (14.52 kg with 8.5 kg of instruments) failed because fourth stage did not ignite.

See also

• Jupiter-C launch vehicle

The Jupiter-C Intermediate Range Ballistic Missile (IRBM) was designed by the Army Ballistic Missile Agency (ABMA) The vehicle consists of a modified Redstone ballistic missile with three solid-propellant upper stages. ...

Reference

• Data Sheet, Department of Astronautics, National Air and Space Museum, Smithsonian Institution.