spacetoday.net: Ulysses mission coming to an end

Posted: Sat, Feb 23, 2008, 9:45 AM ET (1445 GMT)
Ulysses illustration (ESA)

An ESA/NASA mission to study the Sun is approaching its end as the spacecraft is no longer able to keep itself warm. Ulysses, a spacecraft launched by the space shuttle in 1990, is in a solar polar orbit that takes it out to Jupiter's orbit; the spacecraft is currently heading away from the Sun in its orbit. Ulysses's radioisotope power source is no longer able to power the spacecraft's heaters, causing the spacecraft to cool. Project engineers expect that the spacecraft's internal temperature will reach 2°C in the next few weeks, causing the spacecraft's hydrazine fuel to freeze and preventing the spacecraft from maneuvering, effectively ending the mission. Efforts to reroute power from other systems, including the spacecraft's X-band transmitter, have failed. During its mission the spacecraft provided the first observations of the solar poles and returned data on the Sun's magnetic fields and interstellar dust and gas.