Historical Photo of the Month - July 2008

Ulysses Deployment
Photograph Number P-37032

In July 2008 the Ulysses mission will come to an end. The spacecraft is powered by a Radioisotope Thermoelectric Generator (RTG) which has been steadily losing power over the years. It can no longer run all the communications, scientific equipment, and heating at the same time. Soon the spacecraft will become so cold that its hydrazine fuel lines will freeze and it will become impossible to maneuver. Ulysses is a joint mission between NASA and the European Space Agency (ESA).

A five year mission was planned, but for more than 17 years, the spacecraft has studied the Sun, magnetic fields, the solar wind, x-rays and particles from solar flares, and more. Ulysses, first known as the International Solar Polar Mission (ISPM), was launched on the space shuttle Discovery (STS-41) on October 6, 1990 and deployed from the shuttle payload bay 160 nautical miles above Earth. Two booster engines, the Inertial Upper Stage (IUS) and Payload Assist Module (PAM-S) sent Ulysses out of Earth orbit and on its way to Jupiter. The spacecraft used the strong gravity field of Jupiter to bend its trajectory downward into an orbit that circles above and below the Sun's ecliptic plane, where planets and spacecraft usually travel. It takes about 6 years to complete an orbit around the Sun.

For more information about Ulysses, see the October 2005 Historical Photo of the Month, or contact the JPL Archives for assistance. [Archival and other sources: photo index, Ulysses Fact Sheet, Mission Status Reports, news releases, and Ulysses web page.]