One of the most interesting outcomes of the space exploration push in the 60s and 70s was the Voyager program. In August 1977, Voyager 2 was launched on a mission to explore the solar system, followed shortly in September by Voyager 1 (yes, Voyager 2 was launched first, but it travels slower than 1, and has been surpassed). They’ve accomplished a lot, but as Paul Gilster notes at Centauri Dreams, they’re not yet done.
Voyager 1 completed its study of the solar system in 1980 and began its interstellar mission. Voyager 2 achieved this in 1989. At the moment, almost 36 years after their launch, the spacecraft are far out there (but not quite yet out of the solar system, depending on your definition). They’re still sending back scientific information, from such a large distance that it takes light from the Sun over 12 hours to reach them (out to Pluto takes about 5.5 hours). This makes them the farthest man-made objects ever sent out from Earth.
Their scientific missions virtually over, the spacecraft have adopted a new role as artifacts of human civilization, time capsules of everything we were when we launched them. In addition to the craft themselves, which have plenty of meaning (some thoughts on that from Matthew Battle), each of the Voyagers carries on it a Golden Record, a snapshot of our world, a collection of nature images and sounds, snippets of music from a variety of different cultures, greetings in 55 different languages.
But space is immense. It will be 40000 years before Voyager 1 comes close to any other planetary system, and even then it will still be 1.6 light years away. There is virtually zero chance that these records will ever reach anything intelligent enough to decode and understand them. In all likelihood they will drift alone through the darkness of interstellar space for far longer than human civilization will be around. So why did we go through the trouble of making them and sending them out? This supposedly futile act has more to do with mankind than with any attempt to contact an extraterrestrial species. In Carl Sagan’s words,
The spacecraft will be encountered and the record played only if there are advanced space-faring civilizations in interstellar space. But the launching of this bottle into the cosmic ocean says something very hopeful about life on this planet.
Much of the space race had to do with cross-cultural competition, nationalistic displays of military and technological prowess. The Voyager Records are an attempt to acknowledge to ourselves our own impermanence, to rally around the messages of hope and goodwill. Gilster sums it up well,
I think any future archaeologist, human or otherwise, would read into the Voyager spacecraft the desire of a species to transcend itself, hopeful of finding a bridge to other intelligence but pressing on regardless as a way of building meaning into the cosmos.