Launched March 2, 1972, Pioneer 10, built by TRW Inc., Redondo Beach, Calif., is now 7.4 billion miles from Earth. Pioneer 10 was the first spacecraft to pass through the asteroid belt and the first to make direct observations and obtain close-up images of Jupiter. During the passage by Jupiter, Pioneer 10 also charted Jupiters intense radiation belts, located the planets magnetic field, and established that Jupiter is predominantly a liquid planet.In 1983, it became the first man-made object to leave the solar system when it passed the orbit of Pluto, the most distant planet. The spacecraft continued to make valuable scientific investigations in the outer regions of the solar system until its science mission ended March 31, 1997. Pioneer 10s weak signal continues to be tracked by DSN as part of an advanced concept study of communications technology. Pioneer 10 is headed toward the constellation Taurus, where it will pass the nearest star in the constellation in about two million years.
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