CAPE CANAVERAL, Fla. (AP) -- The Ulysses solar probe will cease operations around July 1 after nearly 18 years in outer space, NASA announced Thursday.
The U.S.-European spacecraft has been suffering from a decline in its plutonium power for some time. Despite conservation measures by ground controllers, the power has dwindled to the point where thruster fuel soon will freeze up.
Ulysses already has surpassed its expected lifetime by almost four times, traveling 5.4 billion miles since its launch aboard space shuttle Discovery in 1990.
"When the last bits of data finally arrive, it surely will be tough to say goodbye," European Space Agency mission operations manager Nigel Angold said in a statement.
The $250 million spacecraft studied the sun, in particular its poles and the heliosphere, the region around the sun carved out by the solar wind.