Galileo Millennium Mission Status May 22, 2000

MEDIA RELATIONS OFFICE
JET PROPULSION LABORATORY
CALIFORNIA INSTITUTE OF TECHNOLOGY
NATIONAL AERONAUTICS AND SPACE ADMINISTRATION
PASADENA, CALIF. 91109. TELEPHONE (818) 354-5011

NASA’s Galileo spacecraft has successfully flown past the
largest moon in our solar system — Ganymede, which orbits around
Jupiter.

Galileo dipped to 809 kilometers (503 miles) above the
surface early Saturday, May 20. This was the spacecraft’s first
flyby of Ganymede since May 7, 1997.

“It’s great that things went so smoothly,” said Galileo
Project Manager Jim Erickson of NASA’s Jet Propulsion Laboratory.
“The team was ready for any problems, but they got to relax on
this one. We’re really looking forward to the new pictures and
learning more about this largest of all moons.”

At 4 a.m. PDT, mission controllers at JPL received the
signal indicating that the flyby took place. The spacecraft’s
camera and other instruments were set to capture the flyby with
images and other observations. If all goes as planned, the data
will be transmitted to Earth over the next several months for
processing and analysis.

To fly by Ganymede, Galileo had to approach Jupiter’s
powerful radiation belts. Not surprisingly, the radiation, which
can affect spacecraft instruments, components and systems, did
cause two main resets of Galileo’s main computer. Onboard
software correctly diagnosed this as a false indication, and went
ahead with the Ganymede encounter unaffected.

“It appears that this workhorse spacecraft has done it
again,” Erickson said. Galileo has already survived three times
the radiation it was designed to withstand.

Ganymede is even larger than Mercury and Pluto. Its surface
is a mixture of clean, white ice and dirty, dark ice, with varied
geological formations, including craters, basins, grooves and
rough mountain areas.

Additional information about the Galileo mission is
available at
http://galileo.jpl.nasa.gov.

Galileo was launched from the Space Shuttle Atlantis on
October 18, 1989. After a long journey to Jupiter, Galileo began
orbiting the huge planet and its moons on December 7, 1995, and
successfully completed its two-year primary mission on December
16, 1997. That was followed by a two-year extended mission which
concluded in December 1999, and Galileo is now continuing its
studies under yet another extension, called the Galileo
Millennium Mission. JPL, a division of the California Institute
of Technology in Pasadena, Calif., manages the Galileo mission
for NASA’s Office of Space Science, Washington, D.C.