Fresh lease

The Pioneer 11, which had transmit-ted some spectacular pictures ofJupiter and its moons, is now drifting towards interstellar space some 6.5 billion kin from the earth. Itspower generators, four radioisotopethermoelectric generators and electronic gear have outlived themselves. The spacecraft's radio transmissions are now too weak to be ofany use to scientific research (Science, Vol 269, September 22, 1995).

Surprisingly, its twin - thePioneer 10 - launched in 1972, stillhas a few years of power. By study-ing the Pioneer I I's electronic sys-tems, scientists hope to increase thelife of the other satellite by a few months.