The Pioneer 10 spacecraft is alive and well and still operating after 29 years in space. Currently 11.73 billion km from Earth and on its way towards the constellation Taurus, scientists established contact with Pioneer 10 last Saturday, the first communication since August 2000.
The spacecraft is travelling at more than 44,000 km an hour relative to the sun. Radio signals coming from it take almost 11 hours to reach us.
"Pioneer 10 lives on," stated project manager, Dr Larry Lasher, of the US National Aeronautics and Space Administration. The team had been listening for the Pioneer 10 signal in a one-way transmission since last summer without success, he said.
"We therefore concluded that in order for Pioneer 10 to talk to us, we need to talk to it," he said. A signal was sent to the spacecraft, which locked on to it and returned a signal to a radio telescope antenna in Madrid.
The satellite was launched on March 2nd, 1972, its mission being to capture close-up images of Jupiter and to measure its radiation belts and magnetic field. Data from Pioneer 10 provided evidence that Jupiter is predominantly a liquid planet.
Its primary mission completed, it continued on its way through the outer solar system and finally into the void beyond Pluto. Along the way it measured energetic particles from the sun and incoming cosmic rays. In 1983 it became the first man-made object to leave the solar system and still it continued on its way.
It went on to make valuable scientific readings until its mission finally ended on March 31st, 1997, at a time when it was 10.1 billion km from Earth, and yet it continues to make a contribution.
Contact with Pioneer 10 was raised as part of a test of communication technologies for future interstellar missions according to the NASA team. At its current speed and direction, the satellite will pass by the next nearest star in about two million years. Pioneer 10 carries information about Earth for any extraterrestrial species who happens across the satellite.
Mounted on its side is a gold plaque with an image of a man and a woman and messages of good will. It also pinpoints the Earth in our Milky Way Galaxy and so offers a road map for anyone or anything that might decide to call.
The satellite has achieved a series of firsts including being the first spacecraft to travel through the asteroid belt beyond Mars, the first to give a close-up view of Jupiter and the first to use planetary gravity to change its velocity.
Surprisingly it is not the most distant man-made object, although it did hold that record until February 17th, 1998. On that date its heliocentric radial distance was passed out by the Voyager 1 satellite, which will continue to hold the distance record.
Pioneer 10 was followed by its sister ship, Pioneer 11, which followed its path past Jupiter and then on to photograph Saturn in 1979. It too continues out into space but does so silently.
Its mission ended on September 30th, 1995, when its last transmission was received. Its electrical power source is exhausted and it can no longer point its antenna towards the Earth.