What spacecraft has travelled the farthest?

Voyager 1 left earth on September 5, 1977 - this year marks its 40th anniversary. In August, 2012, 35 years after leaving Earth, Voyager 1 officially left the Solar System and is now traveling in Interstellar space. The craft is currently over 20 trillion kilometers away (about 140 AU - that is, 140 times the distance from the earth to the sun)! After visiting Jupiter, Voyager 1 was supposed to go on and visit Pluto after Saturn. However, after Pioneer 10 discovered that Saturn's moon Titan had an atmosphere, Voyager 1 was reprogrammed to fly by and investigate, causing it to miss the Pluto flyby.

The second farthest spacecraft is Pioneer 10 at 114 AU. Traveling slower than Voyager 1, it was passed in 1998. Voyager's twin - Voyager 2 is at 113 AU, and should pass the distance of Pioneer 10 in the next year. Voyager 2 actually left Earth before Voyager 1. However, it took a longer route out of the solar system so it could visit Uranus and Neptune.

Though many of the scientists and technicians that created Voyager 1 have already retired, the probe itself remains working and in contact with earth through the Deep Space Network. What a trooper!