Galileo Millennium Mission Status 24 May 2001

The camera on NASA’s Galileo spacecraft may not be working
properly as the spacecraft heads toward Jupiter’s moon Callisto
for a close flyby on Friday at 4:24 a.m. (PDT).

“We are not totally surprised, because we knew all along
that Galileo might encounter difficulties from passing close to
Jupiter’s powerful radiation belts,” said Dr. Eilene Theilig,
Galileo project manager at NASA’s Jet Propulsion Laboratory,
Pasadena, Calif. “We are attempting to get a better understanding
of the problem and to do what we can to minimize the loss of
images.”

Voltage readings received from the camera yesterday and
today are the same as when the camera was in a problem state
during its last previous flyby, passing the moon Ganymede five
months ago. During that flyby the condition was intermittent. It
self-corrected spontaneously several times and was also corrected
by commands from the ground to cycle its power off and on. More
than half of the 120 images taken during that encounter period
were captured successfully.

This week, however, indications of the problem began shortly
before this orbit’s closest approach to Jupiter on Wednesday
morning and have persisted in every voltage reading received
since then, even after the power-cycle commands, Theilig said
mid-day Thursday.

“We may have lost the camera images scheduled so far, but
the bulk of the camera observations are tomorrow morning at
Callisto,” she said.

Other scientific experiments on Galileo, including infrared
imaging of Jupiter’s clouds and a radio study of Jupiter’s
atmosphere, have functioned properly during this pass through the
inner portion of Jupiter’s system. Data will be transmitted to
Earth during the next two months.

This is Galileo’s 30th orbit of Jupiter since arriving at
the giant planet in 1995. The original mission lasted two years
in orbit, but the mission has been extended three times. By
repeatedly passing through the highly radioactive environment
close to Jupiter, Galileo has endured more than three times as
much radiation as it was designed to withstand. Radiation damage
to an electronic component is the main suspect in the camera’s
problem.

Additional information about the Galileo mission is
available at http://galileo.jpl.nasa.gov . JPL, a division of the
California Institute of Technology in Pasadena, manages the
Galileo mission for NASA’s Office of Space Science, Washington,
D.C.