Launched from Cape Canaveral atop an Atlas-Centaur rocket, Pioneer 10 became the first human-made object to travel through the asteroid belt, the first to fly by Jupiter and, ultimately, the first spacecraft set on a trajectory to leave the solar system. It carried a gold-anodized plaque intended as a message to any intelligence that might one day find it.
In early March 1972, engineers at Cape Canaveral put the finishing touches on Pioneer 10, a modest 570-pound spacecraft about the size of a small car, that would soon attempt something no human-made object had done before: cross the asteroid belt, a region many scientists feared might be dense enough with debris to destroy any craft attempting passage.
Bolted to its frame was a small gold-anodized aluminum plaque designed by Carl Sagan and Frank Drake, engraved with a diagram of a man and woman, the solar system, and pulsar timing maps meant to indicate Earth's location, a message intended not for anyone alive but for whoever, or whatever, might intercept the spacecraft millions of years in the future as it drifted through interstellar space.
Pioneer 10 launched on March 2, 1972, and by the time it flew past Jupiter in December 1973 it had already proven the asteroid belt navigable. It continued transmitting faint signals back to Earth until 2003, by which point it was billions of miles away, the most distant human-made object then known, a small emissary launched in the same week that the ground crews at Cape Canaveral were still tightening its final bolts.