Major achievements can take a long time – such as 36 years in the case of one that America's space agency announced this month. Voyager 1, a craft launched in 1977, made history by becoming the first human-made object to leave our solar system. This long-flying spaceship is now 12 billion miles from Earth, beyond the sun's atmosphere. The distance is so vast that it takes 17 hours now for its radio signals to reach NASA receivers.

The original goal was to survey the planets Jupiter, Saturn, Uranus and Neptune -- a task it and a craft called Voyager 2 completed in 1989. They were then steered toward deep space. Their radioactive plutonium power sources are expected to stop supplying electricity in about 10 years, at which point their instruments and transmitters will die – though the hardy probes will continue to float silently through interstellar space.

Years ago, Voyager 1 sent back some of the earliest close-ups of Jupiter and Saturn, as well as a distant photo of Earth as a pale blue dot in space. The discovery of active volcanoes on Jupiter’s moon Io, of the intricate nature of Saturn’s beautiful rings and of many more moons than were previously known around each of the four outer planets are examples of the project's many additions to knowledge about our solar system.

NASA says: "This is one of those journeys of exploration, like circumnavigating the globe for the first time or having a footprint on the moon the first time." -- Ed Stone, project's chief scientist

British astronomer says: "It's utterly astonishing that this fragile artifact, based on 1970s technology, can signal its presence from this immense distance." – Professor Martin Rees

U.S. physicist says: "I don’t know if it’s in the same league as landing on the moon, but it’s right up there — ‘Star Trek’ stuff, for sure. I mean, consider the distance. It's hard even for scientists to comprehend." -- Donald Gurnett, University of Iowa professor