An artist's drawing of NASA's Galileo spacecraft flying above Io. Photo: NASA

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.