Pioneer 10 launches

Just before nine in the evening on 2 March 1972, Florida time, an Atlas-Centaur with an added solid third stage tore off the pad at Cape Canaveral carrying a 258-kilogram spacecraft no bigger than a small car. Pioneer 10 left Earth at 51,682 kilometres per hour, faster than any human-made object before it, crossing the Moon's distance in about eleven hours. Its destination was Jupiter, a world no spacecraft had ever approached, on the far side of a region many scientists genuinely feared would destroy it.

On 15 July 1972 Pioneer 10 entered the asteroid belt, and for the next seven months it threaded roughly 435 million kilometres of space that mission planners could only hope was mostly empty. Nobody knew the true density of small debris; some predicted the spacecraft would be sandblasted to death. It emerged in February 1973 essentially unscathed, retiring one of the great unknowns of deep-space flight and opening the outer solar system to everything that followed.

On 4 December 1973, Pioneer 10 swept within 130,354 kilometres of Jupiter's cloud tops, returning the first close-up images of the giant planet and direct measurements of its ferocious radiation belts and vast magnetic field. Jupiter's gravity then slung the spacecraft outward on a trajectory that would carry it out of the solar system entirely, the first machine ever placed on an interstellar escape path.

Bolted to its antenna struts rode a gold-anodized aluminium plaque, conceived by Carl Sagan and Frank Drake and drawn by Linda Salzman Sagan: a man and a woman, a map of the solar system, and the spacecraft's home located against 14 pulsars. Designed for a 21-month mission, Pioneer 10 transmitted for over three decades; its last faint signal reached Earth on 23 January 2003 from 12.23 billion kilometres away. It now coasts silently toward the star Aldebaran, a journey of some two million years.