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Science Blog ZINC PROJECTS

Solar observing spacecraft ended long running mission

Date: 30-Jun-09
Author: European Space Agency

Ulysses, the joint ESA/NASA solar orbiter mission, finally ended on 30 June 2009 when ground controllers sent commands to shut down the satellite's communications. The event marks the conclusion of one of the longest and most successful space missions ever conducted.

The mission had been predicted to end in July 2008, when the satellite's weakened power supply was expected to fall below the minimum required to keep fuel lines from freezing, without which Ulysses would be uncontrollable.

However, through smart engineering and realtime innovation, controllers determined they could keep the lines from freezing by briefly firing the thrusters every few hours. In fact, Ulysses has continued gathering valuable scientific data throughout most of the past year.

Ulysses passed over both poles of the Sun to characterize the solar environment in 3-D. Courtesy: NASA JPL

During its life, Ulysses made nearly three complete orbits of the Sun. The probe revealed for the first time the three-dimensional character of galactic cosmic radiation, energetic particles produced in solar storms and the solar wind.

Not only has Ulysses allowed scientists to map constituents of the heliosphere in space, its longevity enabled the Sun to be observed over a longer period of time than ever before.

Full story: Ulysses: 12 extra months of valuable science