Ulysses Mission To Conclude
- From: baalke@xxxxxxxxxxxxx
- Date: Thu, 12 Jun 2008 13:38:00 -0700 (PDT)
June 12, 2008
Dwayne Brown
Headquarters, Washington
202-358-1726
dwayne.c.brown@xxxxxxxx
DC Agle
Jet Propulsion Laboratory, Pasadena, Calif.
818-393-9011
agle@xxxxxxxxxxxx
RELEASE: 08-144
INTERNATIONAL MISSION STUDYING SUN TO CONCLUDE
WASHINGTON -- After more than 17 years of pioneering solar science, a
joint NASA and European Space Agency mission to study the sun will
end on or about July 1.
The Ulysses spacecraft has endured for almost four times its expected
lifespan. However, the spacecraft will cease operations because of a
decline in power produced by its onboard generators. Ulysses forever
has changed the way scientists view the sun and its effect on the
surrounding space. Mission results and the science legacy it leaves
behind were reviewed today at ESA Headquarters in Paris.
"The main objective of Ulysses was to study, from every angle, the
heliosphere, which is the vast bubble in space carved out by the
solar wind," said Ed Smith, Ulysses project scientist at NASA's Jet
Propulsion Laboratory, Pasadena, Calif. "Over its long life, Ulysses
redefined our knowledge of the heliosphere and went on to answer
questions about our solar neighborhood we did not know to ask."
Ulysses ends its career after revealing that the magnetic field
emanating from the sun's poles is much weaker than previously
observed. This could mean the upcoming solar maximum period will be
less intense than in recent history.
"Over almost two decades of science observations by Ulysses, we have
learned a lot more than we expected about our star and the way it
interacts with the space surrounding it," said Richard Marsden, ESA's
Ulysses project scientist and mission manager. "Solar missions have
appeared in recent years, but Ulysses is still unique today. Its
special point of view over the sun's poles never has been covered by
any other mission."
The spacecraft and its suite of 10 instruments had to be highly
sensitive, yet robust enough to withstand some of the most extreme
conditions in the solar system, including intense radiation while
passing by the giant planet Jupiter's north pole. The encounter
occurred while injecting the mission into its orbit over the sun's
poles.
"Ulysses has been a challenging mission since launch," said Ed
Massey,
Ulysses project manager at JPL. "Its success required the cooperation
and intellect of engineers and scientists from around the world."
Ulysses was the first mission to survey the environment in space
above
and below the poles of the sun in the four dimensions of space and
time. It showed the sun's magnetic field is carried into the solar
system in a more complicated manner than previously believed.
Particles expelled by the sun from low latitudes can climb to high
latitudes and vice versa, sometimes unexpectedly finding their way
out to the planets. Ulysses also studied dust flowing into our solar
system from deep space, and showed it was 30 times more abundant than
astronomers suspected. In addition, the spacecraft detected helium
atoms from deep space and confirmed the universe does not contain
enough matter to eventually halt its expansion.
Ulysses collected and transmitted science data to Earth during a
5.4-billion mile journey. As the power supply weakened during the
years, engineers devised methods to conserve energy. The power has
dwindled to the point where thruster fuel soon will freeze in the
spacecraft's pipelines.
"When the last bits of data finally arrive, it surely will be tough
to
say goodbye," said Nigel Angold, ESA's Ulysses mission operations
manager. "But any sadness I might feel will pale in comparison to the
pride of working on such a magnificent mission. Although operations
will be ending, scientific discoveries from Ulysses data will
continue for years to come."
Ulysses was launched aboard space shuttle Discovery, Oct. 6, 1990.
rocket motors. Ulysses passed Jupiter on Feb. 8, 1992. The giantFrom Earth orbit, it was propelled toward Jupiter by solid-fuel
planet's gravity then bent the spacecraft's flight path downward and
away from the ecliptic plane to place the spacecraft in a final orbit
around the sun that would take it past our star's north and south
poles.
The spacecraft was provided by ESA. NASA provided the launch vehicle
and upper stage boosters. The U.S. Department of Energy supplied a
radioisotope thermoelectric generator to provide power to the
spacecraft. Science instruments were provided by both U.S. and
European investigators. The spacecraft is operated from JPL by a
joint NASA/ESA team. More information about the joint NASA/ESA
Ulysses mission is available at:
http://ulysses.jpl.nasa.gov
or
http://www.esa.int/esaSC/SEMPEQUG3HF_index_0_ov.html
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