Launched in 1977, NASA’s two Voyager probes surveyed Jupiter and Saturn, with Voyager 2 also visiting Uranus and Neptune before heading out of the Solar System. Voyager 1 has since become the fastest and most distant man-made object in the Universe, travelling at around 61,500km/h at a distance of 17.6 billion km from the Earth. Perhaps most incredible of all, NASA is still in communication with it, despite radio signals taking 16 hours to reach it. Image © NASA.