The Ulysses probe is approaching its end of life. Image: ESA
Reading The Ulysses spacecraft will freeze within the next few weeks as the hydrazine fuel from the probe can no longer be heated. This is due to a malfunction in the power supply. If the temperature of the hydrazine falls below two degrees Celsius, it solidifies and the fuel lines become unusable, the space agency ESA announces. Ulysses orbited the sun for the past 17 years, sending scientists massive amounts of data about the star and its impact on the surrounding space. The spacecraft was launched in 1990 from a space shuttle and sent into a six-year orbit around the sun. The orbit led Ulysses out from the center of our solar system to Jupiter, where the magnet's magnetism gave enough momentum to cross both the north and south poles of the sun. This had been done by no other missile before. As the distance from the sun increases, so does the temperature, which is why heating the hydrazine fuel is essential to the operation of the probe.

The main energy for the drive receives Ulysses from a plutonium reactor, whose natural lifetime is limited by the progressive decay of the radioactive substance, however. During the past few years, the amount of energy has been steadily decreasing, which is why some of the leaders of the mission decided not to switch off permanently needed systems like the transmitter. The sixty watts obtained in this way should also be used for the operation of the scientific measuring instruments and the heating system.

In a test run in January, the staff of the space authorities were not able to put the transmitter back on. After many failed attempts, the Ulysses team now believes that the transmitter is lost and the extra energy has never reached the other systems. "We expect some parts of the probe to reach two degrees soon, " says Richard Marsden, ESA's Ulysses Head of Mission. "However, we will squeeze the last drop of science out of the mission by then." Despite the approaching end, the helper's supervisors can still be satisfied: Ulysses is already flying four times longer than expected.

Communication from the ESA ddp / Livia Rasche advertisement


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