A European probe flies over the Sun's poles.
Sir Patrick Moore gets a guided tour of the Sun probe.
Launched in 1990, the European Ulysses spacecraft became the first probe to fly over the poles of the Sun. The craft returned data about solar activity at high latitudes during a series of flybys. The mission ended in 2009.
Ulysses is a decommissioned robotic space probe whose primary mission was to orbit the Sun and study it at all latitudes. It was launched in 1990, studied the Sun in 1994/1995 and then once more in 2000/2001. In addition several comets were studied by the probe. The space probe was a joint venture of NASA and the European Space Agency (ESA). The last day for mission operations on Ulysses was June 30, 2009.
To study the Sun at all latitudes the probe needed to change its orbital inclination and leave the plane of the Solar System – to change the orbital inclination of a spacecraft a large change in heliocentric velocity is needed. However the necessary amount of velocity change to achieve a high inclination orbit of about 80° far exceeded the capabilities of any launch vehicle. Therefore to reach the desired orbit around the Sun a gravity assist manoeuvre around Jupiter was chosen, but this Jupiter encounter meant that Ulysses could not be powered by solar cells – the probe instead was powered by a radioisotope thermoelectric generator (RTG).
The spacecraft was originally named Odysseus, because of its lengthy and indirect trajectory to study the solar poles. It was renamed Ulysses, the Latin translation of "Odysseus", at ESA's request in honour not only of Homer's mythological hero but also with reference to Dante's description in Dante's Inferno.Ulysses was originally scheduled for launch in May 1986 aboard the Space Shuttle Challenger on STS-61-F. Due to the loss of Challenger, the launch of Ulysses was delayed until October 6, 1990 aboard Discovery (mission STS-41).
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