We sent it on a mission to go out among the stars and tell us about everything we saw - but even its creators didn't expect it to get this far. The Voyager 1 Spacecraft has now passed the outer reaches of our Solar System and is drifting on through interstellar space; yet amazingly, it still manages to communicate with Earth.
Launched over 40 years ago, Voyager's original mission was to pass several of the planets close to Earth and tell us more about them, with radio and photographic records being obtained and sent back to Earth. Having done all that, and survived long past its expected obsolescence, it passed through the heliopause at the edge of the Solar System in April 2012, journeying onward, past the gravitational reach of the Sun. It still has some functionality, taking readings of particles and cosmic rays and sending them back home at regular intervals. NASA believe it will finally lose power somewhere around 2025.