Ulysses (spacecraft)

Ulysses

Ulysses spacecraft
Names	Odysseus
Mission type	Heliophysics
Operator	NASA / ESA
COSPAR ID	1990-090B
SATCAT no.	20842
Website	NASA Page ESA Page
Mission duration	18 years, 8 months, 24 days[1]
Spacecraft properties
Manufacturer	Astrium GmbH, Friedrichshafen (formerly Dornier Systems)
Launch mass	371 kg (818 lb)[1]
Payload mass	55 kg (121 lb)
Dimensions	3.2 m × 3.3 m × 2.1 m (10.5 ft × 10.8 ft × 6.9 ft)
Power	285 watts
Start of mission
Launch date	6 October 1990, 11:47:16 UTC[1]
Rocket	Space Shuttle Discovery (STS-41) with Inertial Upper Stage and PAM-S
Launch site	Kennedy Space Center, LC-39B
Contractor	NASA
End of mission
Disposal	Decommissioned
Deactivated	30 June 2009
Orbital parameters
Reference system	Heliocentric orbit
Perihelion altitude	1.35 AU
Aphelion altitude	5.40 AU
Inclination	79.11°
Period	2,264.26 days (6.2 years)
Flyby of Jupiter (gravity assist)
Closest approach	8 February 1992
Distance	440,439 km (6.3 Jupiter radii)
Ulysses mission patch

Ulysses (/juːˈlɪsiːz/ yoo-LISS-eez, UK also /ˈjuːlɪsiːz/ YOO-liss-eez) was a robotic space probe whose primary mission was to orbit the Sun and study it at all latitudes. It was launched in 1990 and made three "fast latitude scans" of the Sun in 1994/1995, 2000/2001, and 2007/2008. In addition, the probe studied several comets. Ulysses was a joint venture of the European Space Agency (ESA) and the United States' National Aeronautics and Space Administration (NASA), under leadership of ESA with participation from Canada's National Research Council.^[2] The last day for mission operations on Ulysses was 30 June 2009.^[3][4]

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 to about 80° requires a large change in heliocentric velocity, the energy to achieve which far exceeded the capabilities of any launch vehicle. To reach the desired orbit around the Sun, the mission's planners chose a gravity assist maneuver around Jupiter, but this Jupiter encounter meant that Ulysses could not be powered by solar cells. The probe was powered instead by a General Purpose Heat Source Radioisotope Thermoelectric Generator (GPHS-RTG).^[5]

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 honor not only of Homer's mythological hero but also of Dante's character in the Inferno.^[6] Ulysses was originally scheduled for launch in May 1986 aboard the Space Shuttle Challenger on STS-61-F. Due to the 28 January 1986 loss of Challenger, the launch of Ulysses was delayed until 6 October 1990 aboard Discovery (mission STS-41).