Ulysses spacecraft ends 18-year mission

PASADENA, Calif., July 1 (UPI) -- The Ulysses spacecraft, a joint NASA-European Space Agency mission, has officially ceased operations, officials said.

The end-of-mission command was transmitted Tuesday to the spacecraft that operated for more than 18 years, charting the unexplored regions of space above the poles of the sun. When space shuttle Discovery launched Ulysses on Oct. 6, 1990, it had an expected lifetime of five years, NASA said.

"This has been a remarkable scientific endeavor," said Richard Marsden, Ulysses mission manager and project scientist at the European Space Agency. "The results Ulysses obtained have exceeded our wildest dreams many times over."

In addition to measuring the solar wind and charged particles, the spacecraft's instruments measured small dust particles and neutral gases from local interstellar space. NASA said Ulysses also had an unprecedented three chance encounters with comet tails, registering more than 1,800 cosmic gamma-ray bursts and providing findings for more than 1,000 scientific articles and two books.

Ulysses' orbital path is carrying the spacecraft away from Earth, progressively limiting the amount of data transmitted. That prompted Ulysses project managers, with the concurrence of the ESA and NASA, to decide it was an appropriate time to end the "epic scientific adventure," NASA said.

More information about Ulysses is available at http://ulysses.jpl.nasa.gov.