Wednesday, August 5, 1998 Published at 13:02 GMT 14:02 UK
Pioneer 10 calls home
Going where no probe has gone before
One of the most distant space probes ever launched into space has been contacted again and is sending back valuable data about unexplored space. Our science editor Dr David Whitehouse reports
Pioneer 10 was in every sense a pioneering space mission. Launched on March 2nd 1972 it opened the way to the exploration of deep space.
It was the first craft to travel through the asteroid belt, a region of rocky debris between Mars and Jupiter.
It was the first craft to explore Jupiter and on June 13th, 1983, was the first space probe to travel further than the Sun's most distant planet.
Its goal is the so-called heliopause, a region in space where the Sun's influence ends and true interstellar space begins. No spacecraft has ever reached it.
Pioneer 10's mission formally ended in 1997 but as part of a training program controllers of the Lunar Prospector spacecraft in orbit around the moon detected it once again.
It's still working 10.6 billion km (6.6 billion miles) away. It is so distant that light takes 19h 40m to reach it.
It is heading towards the red star Aldeberan, the main star in the constellation of Taurus. It should get there in 2 million years time.
In the unlikely event that any form of life should find it it contains a plaque telling them about the creatures that built it.