PARIS, July 3 (UPI) -- The European Space Agency said its Ulysses spacecraft, whose mission was expected to end Tuesday, is still operating.
But ESA said spacecraft controllers are waiting for a sign of the expected fuel freeze that will end the mission.
"Controllers will know that the fuel needed to keep the antenna pointing towards Earth has started to freeze when Earth-pointing maneuvers become less efficient and the radio signals from the spacecraft grow weaker," ESA scientists said in a statement.
But while the spacecraft is still operating, it is providing important science data as it pursues its exploration of the heliosphere -- the sun's sphere of influence. Although the spacecraft can now transmit data only in real time, ESA said the amazing 17.5-year-old mission continues to add to the wealth of information collected so far.
Ulysses is a joint mission between ESA and the National Aeronautics and Space Administration.