Some of the best evidence yet for existence of a liquid ocean under Europa's surface is being collected and analyzed by Arizona State University scientists this week from pictures being transmitted to Earth by the Galileo spacecraft. A dozen observations will be transmitted this week, half of them containing Europa data and the other half providing information on Jupiter and its rings. The information was stored on Galileo's onboard tape recorder during the September 26 Europa flyby.

The Europa observations include a mosaic of images taken by the spacecraft camera showing several terrain types which scientists say show strong evidence of a liquid ocean or mobile substance-similar to an iceberg found on Earth-near Europa's surface, said Sarah Fagents, an ASU postdoctoral research assistant.

"It is very exciting," said Fagents. "Each time we receive a transmission we see something new. We are trying to determine if the substance is liquid, and if it exists in that form today or in the past. It will take more work to know definitely."

Galileo's camera and the near infrared mapping spectrometer is also returning three observations of Jupiter's newest white oval, a swirling storm system formed earlier this year when two smaller storms merged. Two images display Jupiter's rings under varying lightening conditions. This will help scientists better determine the size and quantity of the particles contained in the rings.

Playback of the images will be interrupted on Thursday, Nov. 5, for a standard gyroscope test. The next Europa flyby is scheduled for Nov. 22. The Galileo Europa Mission is managed by the Jet Propulsion Laboratory for NASA's Office of Space Science, Washington, D.C.

Sources:
Patrick Burkhart, 602-965-8751
Ron Greeley, 602-965-7045