Pioneer Program

Pioneer at TRW. Date: 1971 Source: NASA

Pioneers, 0,1, and 2, were launched in an attempt by the U.S. to leave Earth's orbit. They were designed to go into orbit around the moon, and photograph its surface, but all suffered some sort of launch failure and none of them were in flight for over 7 hours.

Pioneer 0 was launched by the USAF (United States Air Force) on August 17, 1958. 77 seconds following its launch Pioneer 0 was destroyed when the rocket's first stage exploded. Soon after this attempt, Pioneer 1 and 2 were turned over to the newly formed National Aeronautics and Space Administration (NASA).

NASA launched Pioneer 1 first, but due to a programming error in the launch vehicle upper stage, it was not given enough velocity to clear the Earth's gravitational field. It stayed in flight for about 2 days, and did manage to provide data on the extent of the earth's radiation belts.

Pioneer 2, launched on November 8, 1958, also suffered a launch failure. It re-entered the earth's atmosphere 6 hours and 52 minutes after launch, and did not provide any significant information.

Pioneer 3, launched on December 6, 1958, was smaller than the previous Pioneers. Both it and Pioneer 4 carried only a single experiment to detect cosmic radiation. Pioneer 3 was planned to flyby the moon, but it failed when the launch vehicle's first stage cut-off prematurely. Although Pioneer 3 didn't have sufficient velocity and couldn't escape earth's gravitational pull, it did reach an altitude of 102,332 km and discovered a second radiation belt around Earth.

Pioneer 4, launched on March 3, 1959, was launched successfully, and it became the first American spacecraft to escape Earth's gravitational pull. Pioneer 4 passed within 58,983 km. of the moon, and returned data on the radiation in the moon's environment.

Pioneer 5, launched on March 11, 1960, was the second successful mission under the Pioneer program. Pioneer 5 was put into a heliocentric orbit between Earth and Venus. It was designed to provide the first map of the interplanetary magnetic field. Pioneer 5 functioned for a record 106 days, and communicated with Earth from a distance of 36.2 million km.

Pioneers 6-9 were launched into solar orbits approximating that of Earth. Pioneer 6 was launched on December 16, 1965; Pioneer 7 was launched on August 17, 1966; Pioneer 8 was launched on December 13, 1967; and Pioneer 9 was launched on November 8, 1986. They were designed to explore interplanetary space and carry out observations of the sun, and like Pioneer 5, they were put into heliocentric orbits between Earth and Venus and studied various solar phenomenon including the structure and flow of the solar wind, and solar flares.

Pioneer E, launched on August 27, 1969, was lost when it failed to orbit due to first stage hydraulics failure.

Pioneer 10, launched on March 2, 1972, was the first spacecraft ever to fly though the asteroid belt, and it also was the first spacecraft to obtain close-up images and make direct observations of Jupiter. Pioneer 10 was equipped with instruments that enabled it to study Jupiter and Saturn's atmospheres, magnetic fields, moons, and rings. The craft made scientific investigations in the outer regions of the solar system until its mission ended on March 31, 1997. Pioneer 10 is now headed in the direction of the constellation Taurus (The Bull). It will take the Pioneer 10 probe over 2 million years to pass by one of the closest stars in the constellation.

Pioneer 11, launched on April 5, 1973, followed Pioneer 10 to Jupiter, and flew by in December, 1974. During its closest approach to Jupiter, on December 4, 1974, Pioneer 11 passed within 34,000 km. of its cloud tops. Both Pioneer 10 and Pioneer 11 used Jupiter's gravitational field to alter their course, and in September, 1979, it made the first ever direct observations of Saturn and studied energetic particles in the outer heliosphere. On September 1, 1979, Pioneer 11 passed by Saturn at a distance of 21,000 km. from the cloud tops. On September 30, 1995, the last transmission was received from Pioneer 11, and its mission ended. At this point it was no longer capable of operating any of its scientific equipment, and it was unable to point its antenna towards Earth. Pioneer 11 is currently headed towards the constellation Aquila ( The Eagle). It will take Pioneer 11 about 4 million years to pass near one of the stars in that constellation.

Pioneer 12 ( Pioneer Venus Orbiter), was launched on May 20, 1978. On December 4, 1978, it was injected into a highly elliptical orbit around Venus. The low orbital point, or periapsis, of the orbit was about 93 miles (150 km) above the surface. The highest point, or apoapsis, was about 41,000 miles (66,000 km) above the surface. Pioneer's orbital period was 23 hours 11 minutes. After entering orbit, Pioneer began returning global maps of the planet's clouds, atmosphere and ionosphere, measurements of the atmosphere-solar wind interaction and radar maps of most of the planet's surface. Pioneer also took advantage of several opportunities to study several comets. In 1991 the Radar Mapper was reactivated and Pioneer investigated portions of the planet that had been previously inaccessible. In September, 1992, controllers used the fuel that remained in a series of maneuvers to keep altitude for as long as possible. On October 8, 1992, the fuel supply was finally exhausted, and the Orbiter ended its mission by entering the Venusian atmosphere. The Pioneer Venus Orbiter had been orbiting Venus for 14 years.

On August 8, 1978, Pioneer 13 (Pioneer Venus Multiprobe) was launched. The Multiprobe consisted of a bus which was used to carry one large and three smaller probes. The large probe was released from the Bus on November other three were released four days later on November 20, 1978. Two of the probes were 16, 1978, and the targeted at the night side of Venus, and one was targeted at the day side. After being released, the probes went "off the air" for a whileprogrammed to come back on the air again three hours before beginning their descent through the . They were atmosphere of VenusDecember 9, 1978, just 22 minutes before entry, the large probe began to transmit signals back to . On Earthprobes started transmitting signals back to Earth just 17 minutes before entering the atmosphere. Even . All of the smaller though none of the probes were designed to withstand the crash into the Venusian surface, one small probe kept transmitting data from the surface for 67 minutes.

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