File:Pioneer 10 a - Smithsonian Air and Space Museum - 2012-05-15 (7275640524).jpg

An engineering back-up of Pioneer 10, the space probe to visit Jupiter and the first spacecraft to escape the Solar System. On display at the Smithsonian Air and Space Museum.

With a rare alignment of the outer planets of the Solar System coming up in the 1970s, American space scientists began planning a host of missions to the outer solar system. In 1964, University of Iowa physicist James A. Van Allen helped convince NASA to launch a pair of "Jupiter probes". NASA approved the project in February 1969, with the spacecraft named Pioneer 10 and Pioneer 11. Initially, the goal was to study what space was like past Mars, study the asteroid belt, and explore Jupiter. Another objective -- to see what effect Jupiter's radiation would have on the instruments -- was added later.

TRW was paid $380 million to build both Pioneer 10 and Pioneer 11.

Pioneer 10 was a hexagon just 14 inches deep and 30 inches long. The main body of the spacecraft contained propellant for the attitude thrusters and eight of the 11 scientific instruments. Protection from meteorites came from a metal honeycomb shell surround the instruments, as well as a thermal blanket. Heat was generated by the instruments themselves, but the spacecraft could be cooled by opening louvers in its shell.

Pioneer 10 spun on its axis 4.8 times per minute to make sure it was stable. Two small nuclear reactors provided power, and were extended away from the spacecraft on a long boom 10 feet long. The reactors were intended to function for 29 years, but the connections feeding electricity from the reactors to the spacecraft deteriorated so that no enough power was flowing to the instruments.

Pioneer 10 carried two S-band antennas -- one a narrow-beam, high-gain antenna with a 9 foot wide parabolic dish and the other an omni-directional, medium-gain antenna. The on-board computer could retain five commands in its memory. There were just 222 commands possible. The computer could store up to 6kb of information, which it then transmitted back to Earth.

Pioneer 10 carred a bunch of science experiments: a magnetometer for detecting magnetic fields; a solar wind detector; a cosmic ray detector; a cosmic ray particle composition and energy range detector; a radiation detector that could identify the intensity, energy, and direction of radioactive particles; a meteoroid detector; and visual meteoroid-asteroid tracking device (for close-by micrometeors and for distant asteroids); an ultraviolet photometer to look for hydrogen and helium; a visual camera that could take photos in red and blue light; and an infrared radiometer to measure cloud temperature on Jupiter.

The Pioneer 10 probe was launched on March 3, 1972. Pioneer 10 was the fastest man-made object in the universe at the time. It was the first spacecraft to detect interplanetary atoms of helium, the first to detect high-energy ions of aluminum and sodium in the solar wind, the first to to enter the asteroid belt, and the first to visit Jupiter.

Pioneer 10 crossed the orbit of Saturn in 1976 and the orbit of Uranus in 1979. The mission came to an official end on March 31, 1997. It was 67 astronomical units (AU; the distance from the Earth to the Sun) from the Sun.