Contact: Jim Doyle
MAGELLAN STATUS REPORT
FOR IMMEDIATE RELEASE October 12, 1994
The successful five-and-a-half-year mission of NASA's Magellan
spacecraft to map the surface and measure the gravity of Venus ended
today when ground controllers lost contact with the spacecraft.
Magellan is expected to burn up in the planet's upper atmosphere
within two days.
The final chapter of the Magellan story was written as Earth-based
tracking stations lost the spacecraft's radio signal at 10:02
Universal Time (3:02 a.m. Pacific Daylight Time). The loss of signal,
which was anticipated, was due to low power on the spacecraft,
exacerbated by Magellan's orientation as it performed a final
experiment in the upper atmosphere of Venus.
The spacecraft's thrusters were fired in four sequences on Tuesday,
Oct. 11, to lower Magellan's orbit into the thin upper atmosphere and
set up the final experiment, before the spacecraft's failing power
system or dynamic forces and friction from the Venusian atmosphere
shut off communication.
Magellan gathered scientific data on the planet's upper atmosphere,
including aerodynamic interactions with it during the spacecraft's
final descent, by orienting its wing-like solar panels in opposite
directions, like a windmill. The termination experiment was an
extension of the windmill experiment performed in early September. It
was carried out as the spacecraft was within weeks, if not days, of
the end of its useful life due to expected decreases in solar power
output from the thermal stress produced by more than 15,000 orbits of
Venus.
Launched in May 1989, Magellan entered Venus orbit in August 1990 and
gathered data for over four years. The mission exceeded all of the
objectives defined for its exploration of Venus.
It used radar to map 98 percent of the planet's cloud- covered surface
to an average resolution of better than 300 meters and compiled a
high-resolution, comprehensive gravity field map for 95 percent of the
planet. The gravity data will allow scientists to see "underneath the
planet's skin" and compare that knowledge of the interior to the
wealth of surface features revealed by Magellan's radar imaging, said
Project Manager Doug Griffith at NASA's Jet Propulsion Laboratory
(JPL), Pasadena, Calif.
"The tremendous success of the Magellan program was made possible by
the dedicated NASA, JPL , Martin Marietta (Denver) and Hughes Aircraft
(Los Angeles) team that built the spacecraft and its radar, and
operated the mission," Griffith said. "The data which streamed back
from Magellan's radar images, its atmospheric studies, and its gravity
data acquisition maneuvers have built a vast database of new knowledge
about Venus and the formation of the solar system that will be studied
by scientists for decades to come."
Magellan also performed a first-of-a-kind "aerobraking" maneuver by
dipping into the atmosphere to reshape its orbit. This technique is
now being used in the design of the Mars Global Surveyor mission to
enable the spacecraft to enter orbit around the planet Mars in 1997
using less fuel, resulting in significant savings of weight and cost.
"The Magellan mission to Venus has been successful beyond all
expectations," said JPL Director Dr. Edward C. Stone. "It not only
fulfilled its science and mission objectives, it also demonstrated
innovative technologies for future missions."
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- T o d d E. V a n H o o s e a r -
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(._.) Michigan State University - East Lansing, MI USA
(_) Computer Laboratory - Department of Communication
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