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1993-05-03
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PUBLIC INFORMATION OFFICE
JET PROPULSION LABORATORY
CALIFORNIA INSTITUTE OF TECHNOLOGY
NATIONAL AERONAUTICS AND SPACE ADMINISTRATION
PASADENA, CALIF. 91109. TELEPHONE (818) 354-5011
Contact: Diane Ainsworth
FOR IMMEDIATE RELEASE July 8, 1991
The Ulysses spacecraft fired two small thrusters today to
set the final course for its early February 1992 rendezvous with
Jupiter.
The trajectory correction maneuver, conducted by the mission
operations team at the Jet Propulsion Laboratory, was the last
change to the spacecraft's flight path before Ulysses completes
its 484-million-mile journey to Jupiter. The 8½-minute maneuver
began at 6:24 a.m. Pacific Daylight Time.
NASA and European Space Agency officials said the maneuver
was minor and was designed to alter the spacecraft's trajectory
by about 0.29 meters per second (less than one foot per second).
The trajectory correction will trim approximately four minutes
off Ulysses' arrival time at Jupiter.
Ulysses is presently traveling in the ecliptic plane -- the
plane in which the planets of the solar system orbit -- at a
heliocentric velocity of approximately 68,000 kilometers per hour
(44,000 miles per hour). The spacecraft is slowing as it nears
Jupiter, but is still closing on the planet at a little more than
one million kilometers per day (832,000 miles per day).
The 810-pound spacecraft is expected to enter the Jovian
magnetosphere about Feb. 3, 1992, and begin making measurements
during a 10-day sweep past the planet. The magnetosphere is the
1
region of space dominated by the magnetic field of the planet.
Ulysses, on its approach, will fly through a previously
unexplored region of Jupiter's magnetosphere at about 30 degrees
north latitude on the morning side of the planet. Closest
approach of 6.3 Jupiter radii (279,300 miles) from the center of
the planet will occur at 4 a.m. Pacific Standard Time on
Saturday, Feb. 8, 1992.
Approximately a week later, the spacecraft will exit the
magnetosphere at high southern latitudes on the evening side of
the planet.
Many of the Ulysses science experiments are expected to
yield new information about Jupiter's magnetic field and particle
environment. Ulysses will determine the composition of energetic
particles trapped in the magnetic field, look for X-ray emissions
and investigate the properties of the solar wind in the region
influenced by the planet.
After the encounter, the momentum gained from the
gravitational pull of Jupiter will swing Ulysses out of the
ecliptic plane and onto a trajectory leading over the southern
solar pole. In June 1994, the spacecraft will reach 70 degrees
south solar latitude and begin its primary mission of exploring
the polar regions of the sun.
Ulysses is a five-year mission managed jointly by NASA's
Office of Space Science and Applications and the European Space
Agency. Tracking and data collection are provided by NASA's Deep
Space Network, which is managed by the Jet Propulsion Laboratory.
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