Pioneer 10/11

For over 30 years, the Pioneer 10 spacecraft sent photographs and scientific information back to Earth. Launched March 2, 1972, it reached speeds of 52,100 kilometers (32,400 miles) per hour on its flight to Jupiter, making it one of the fastest human-made objects ever. After completing an investigation of Jupiter, Pioneer 10 continued on to the outer regions of the solar system, studying solar wind and cosmic rays.

Having gone further into space than any other object sent from Earth, Pioneer's last weak signal was received on January 22, 2003, from approximately 12.2 billion kilometers (7.6 billion miles) from Earth. NASA engineers reported that Pioneer 10's radioisotope power source had degraded and was not likely to allow future transmissions.

As it drifts into interstellar space, Pioneer 10 will continue to carry a plaque designed to inform intelligent life that may find it about the spacecraft and its origins. The prototype spacecraft displayed here was constructed for NASA by TRW, Inc.

During the latter 1960s, G.A. Flandro, a JPL scientist, discovered that once every 176 years both the Earth and all the giant planets of the Solar System gather on one side of the Sun. This geometric line-up made possible close‑up observation of all the planets in the outer solar system (with the exception of Pluto) in a single flight, the "Grand Tour." The flyby of each planet would bend the spacecraft's flight path and increase its velocity enough to deliver it to the next destination. This would occur through a complicated process known as "gravity assist," something like a slingshot effect, whereby the flight time to Neptune could be reduced from 30 to 12 years. Such a configuration was due to occur in the late 1970s, and it led to one of the most significant space probe efforts undertaken by the U.S.

To prepare the way for the "Grand Tour," NASA conceived Pioneer 10 and Pioneer 11 as outer solar system probes. Both were small, nuclear‑powered, spin‑stabilized spacecraft that Atlas‑Centaur launched. The first of these was launched on 3 March 1972, and encountered Jupiter in early December 1973. On 22 January 2003, when Pioneer 10’s signal was last detected, the spacecraft had travelled 82 AU (7.6 billion miles) from Earth, more than twice the distance from the Sun to Pluto. In 1973, NASA launched Pioneer 11, providing scientists with their closest view of Jupiter, from 26,600 miles above the cloud tops in December 1974. The close approach accelerated the spacecraft's speed to 107,373 mph, by far the fastest ever reached by a an object from Earth, and hurled Pioneer 11 1.5‑billion miles across the Solar System toward Saturn.