Contact has been lost with Pioneer 10, about 11 billion km (7 billion miles) from the Earth, and is unlikely to be re-established, says NASA's Deep Space Tracking Network. Two-way communications between the Earth and Pioneer take 21 hours. The craft, launched in 1972, was the first to leave the solar system after its exploration of the planet Jupiter in 1973. It has since been followed into deep space by Pioneer 11 and Voyagers 1 and 2. Voyager 1 - at 11.5 billion km, the furthest away from Earth - is conducting the Voyager Interstellar Mission, characterising the environment beyond the sun's sphere of influence.
Source: Flight International