About the size of a minivan with a flagpole sticking out of its side, Galileo weighed two and a half tons fully loaded. It contained a suite of scientific instruments, two communications antennae, thruster rockets, and radioisotope thermoelectric generators to provide power. Galileo’s mini-probe, about the size of a dishwasher, contained six scientific instruments of its own, designed to measure the conditions of its surroundings as it descended by parachute into Jupiter’s atmosphere.
The Galileo probe made an extensive survey of Jupiter and its Galilean moons. (NASA)