Ulysses Mission

The Ulysses spacecraft is an international project to study the poles of the sun and interstellar space above and below the poles. The mission, managed jointly by NASA's Jet Propulsion Laboratory and the European Space Agency, is designed to study three major topics in solar physics: the sun, the solar wind and interstellar space. The instruments of Ulysses will study those phenomena at nearly all solar latitudes, but the most important work will be at high solar latitudes, near the polar regions of the sun that have not been explored by other spacecraft.

Ulysses is a 370-kilogram (8l4-pound) spacecraft that was sent into an orbit at right angles to the solar system's ecliptic plane using a gravity-assist on Feb. 8, 1992 from Jupiter. (The ecliptic is the plane in which the Earth orbits the sun.) The orbit will allow Ulysses to examine, for the first time, the regions of the sun's north and south poles.

Scientific data returned by Ulysses will aid scientists in their studies of the sun and of space beyond the solar system. All spacecraft that have studied the sun previously have done so in or near the ecliptic plane. But the sun's magnetic and electric fields and the solar wind have a strong influence on interplanetary space in that region. Because of the structure and shape of the sun's magnetic field, scientists expect to see very different phenomena, both outbound from the sun and inbound from interstellar space, in the polar regions.

The first high latitude solar pass began when Ulysses reached 70 degrees south solar latitude in June l994. Ulysses has spent about four months above that latitude, about 2.2 astronomical units from the sun. (An astronomical unit is about l50 million kilometers or 93 million miles, the average distance between the sun and the Earth.) Ulysses will cross the sun's equator in February l995 and then continue toward the north pole. During its second polar passage, beginning in June 1995, Ulysses has spent four months at latitudes greater than 70 degrees. The primary mission was completed in October 1995. Currently Ulysses is beginning continuing on it&s eliptical orbit towards another intercept of the ecliptic at about 5.4 AU in early 1998.

Ulysses' scientific payload is composed of nine instruments which include:

  • Magnetometers
  • A solar-wind plasma experiment
  • A solar-wind ion-composition spectrometer
  • An energetic-particle composition experiment
  • A low-energy charged-particle detector
  • A cosmic-ray and solar-particle instrument
  • A unified radio and plasma-wave experiment
  • A solar-flare X-ray and cosmic gamma-ray burst experiment
  • A cosmic-dust experiment

In addition, the spacecraft radio signal is used to conduct a coronal-sounding experiment and a gravity-wave search.

The science instruments for Ulysses were provided by the U.S. and European science teams. The spacecraft was built by Dornier Systems of Germany, for ESA, which is responsible for on-orbit operations. NASA provided the space shuttle Discovery and the IUS and PAM-S upper stages and the radioisotope thermoelectric generator, which was built for the U.S. Department of Energy by the General Electric Co.

Jet Propulsion Laboratory manages the U.S. portion of the mission for NASA's Office of Space Science and Applications. Ulysses is being tracked and data gathered by NASA's Deep Space Network, which is operated by JPL. Spacecraft operations and data analysis are being performed at JPL by a joint ESA/JPL team.

Text excerpted from information provided by JPL-PIO 2/1/92.

MISSION TIMELINE
EVENT DATE
Launch Oct. 6, l990
Jupiter encounter Feb. 8, l992
First solar polar passage (max. lat.) June l994
Cross solar equator February l995
Second solar polar passage (max. lat.) June l995
End of primary mission Oct. l, l995
Cross solar equator at 5.4 AU January 1998