The ONE mission that has surpassed all others for longevity are the Voyager I and II spacecraft. Their purpose was to tour the planets, Jupiter, Saturn, Uranus and Neptune. The voyager craft sent back LIVE TV pictures. I remember the night I stayed up until 2 AM st see the pictures from the first flyby of Jupiter. This was 1979 by the way, 2 years after the launch in 1977. Today, they are roughly 8 and 10 billion miles away and still going strong, getting further away at the rate of 35,000 MPH, almost at he edge of what we think of as our solar system. They are at the edge of interstellar space, where there is no "solar wind" from our sun. It takes over 9 hours one way for radio transmissions. And, think about this, the transmitter only has 25 watts of power... yet we can hear it as it reports on the environment it is in as it continues the job of looking around to see what is out there...
