Galileo Mission Status January 4, 2000

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

Engineers say it appears that NASA’s Galileo spacecraft has chalked up its first successful encounter of the year 2000. This encounter
began when the spacecraft flew over Jupiter’s icy moon Europa on Monday morning, January 3, at an altitude of 351 kilometers (218 miles).
Galileo then performed observations of three of Jupiter’s smaller moons — Amalthea, Thebe and Metis — at 7:30 p.m. Pacific Standard Time
on Monday. The encounter was capped off with several observations of Jupiter’s volcanic moon Io at about 4 a.m. PST Tuesday, January 4.

The spacecraft is operating normally, and engineers believe all the observations were successfully recorded on Galileo’s onboard tape
recorder. The recordings will be transmitted to Earth starting on Wednesday, January 5.

During this flyby, it appears that Galileo’s instruments completed observations designed to detect any magnetic disturbances triggered by
electrical currents set up in a possible ocean lying beneath Europa’s icy crust.

While Galileo passed behind Europa during the flyby, its radio signal to Earth was blocked. Scientists studied the signal changes to learn
more about the moon’s ionosphere — a region of charged particles that surrounds it — and any possible atmosphere.

Radiation levels during this encounter were about average for the region. The only apparent effects of the radiation were false
indications of computer resets onboard the spacecraft, a common radiation-related occurrence during previous Galileo encounters. Onboard
software successfully handled these errors, and the flyby continued.

Since December 1995, Galileo has been orbiting Jupiter and its moons, passing through a zone of intense radiation. In fact, the
spacecraft has already survived more than twice the radiation it was designed to withstand, and it has beamed to Earth unprecedented
images and other information.

JPL, a division of the California Institute of Technology, Pasadena, CA, manages the Galileo mission for NASA’s Office of Space
Science, Washington, DC.