Ulysses Encounter With Jupiter 1991 NASA; Solar Astronomy Satellite Orbiting Sun’s Poles

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About the Ulysses Mission to the Sun. Ulysses used the gravity of Jupiter to lift it out of the ecliptic plane into polar orbit around the Sun.

Public domain film from NASA, slightly cropped to remove uneven edges, with the aspect ratio corrected, and one-pass brightness-contrast-color correction & mild video noise reduction applied.
The soundtrack was also processed with volume normalization, noise reduction, clipping reduction, and/or equalization (the resulting sound, though not perfect, is far less noisy than the original).


Ulysses is a decommissioned robotic space probe that was designed to study the Sun as a joint venture of NASA and the European Space Agency (ESA). The spacecraft was originally named Odysseus, because of its lengthy and indirect trajectory to near Solar distance. 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. Originally scheduled for launch in May 1986 aboard the Space Shuttle Challenger. Due to the loss of Challenger, the launch of Ulysses was delayed until October 6, 1990 aboard Discovery (mission STS-41). The spacecraft’s mission was to study the Sun at all latitudes. To do this required a major orbital plane shift. Due to velocity change limitations of the Shuttle and the Inertial Upper Stage (IUS), this was accomplished by using an encounter with Jupiter to effect the plane change instead of an engine burn. The need for a Jupiter encounter meant that Ulysses could not be powered by solar cells and was powered by a radioisotope thermoelectric generator (RTG) instead.

By February 2008, the power output from the RTG, which is generated by heat from the radioactive decay of plutonium-238, had decreased enough to leave insufficient power for internal heaters to keep the spacecraft’s attitude control hydrazine fuel from freezing. The end of mission was at one point scheduled for July 1, 2008, but mission scientists came up with a method to keep the fuel liquid by conducting a short thruster burn every two hours, allowing the mission to continue. The cessation of mission operations and deactivation or hibernation of the spacecraft was determined by the inability to prevent attitude control fuel from freezing. The last day for mission operations on Ulysses was June 30, 2009… The last scheduled ground station pass of the mission was over the Madrid Deep Space Network 70m ground station (DSS-63) from around 15:35 to 20:20 UTC. There were no decommissioning engineering tests on the spacecraft…

Originally, two spacecraft were to be built by NASA and ESA, as the International Solar Polar Mission… the US spacecraft was canceled in 1981. One spacecraft was designed, and the project recast as Ulysses, due to the indirect and untried flight path. NASA would provide the Radioisotope Thermoelectric Generator (RTG) and launch services, ESA would build the spacecraft assigned to Astrium GmbH, Friedrichshafen, Germany (formerly Dornier Systems)…

The changes delayed launch from February 1983 to May 1986 where it was to be deployed by the Space Shuttle Challenger, however, the Challenger disaster pushed the date to October 1990…

It arrived at Jupiter February 8, 1992 for a swing-by maneuver that increased its inclination to the ecliptic by 80.2 degrees. The giant planet’s gravity bent the spacecraft’s flight path southward and away from the ecliptic plane. This put it into a final orbit around the Sun that would take it past the Sun’s north and south poles. The size and shape of the orbit were adjusted to a much smaller degree so that aphelion remained at approximately 5 AU, Jupiter’s distance from the Sun, and perihelion was somewhat greater than 1 AU, the Earth’s distance from the Sun. The orbital period is approx 6 years…

Solar southern polar regions

Between 2000 and 2001 it explored the southern solar polar regions, which gave many unexpected results. In particular the southern magnetic pole was found to be much more dynamic than the north pole and without any fixed clear location; instead, it is diffusely located…

– Ulysses discovered that the Sun’s magnetic field interacts with the Solar System in a more complex fashion than previously assumed.

– Ulysses discovered that dust coming into the Solar System from deep space was 30 times more abundant than previously expected.

– In 2007-2008 Ulysses determined that the magnetic field emanating from the Sun’s poles is much weaker than previously observed.

– That the solar wind has “grown progressively weaker during the mission and is currently at its weakest since the start of the Space Age…


Hugh Jaanus says:

What you talking about Willis.

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