Galileo returns images from Jupiter and its moon Europa

Photo courtesy of NASA at http://www.jpl.nasa.gov/galileo/sepo/ The planet Jupiter, with its redspot facing out, is pictured as seen from the Galileo spacecraft. The spacecraft has allowed scientists to study Jupiter's atmosphere, which has some characteristics of the aurora borealis near the Earth's North Pole.

University of Arizona scientists got a glimpse of Jupiter's atmosphere last week as recent images were broadcast from the Jet Propulsion Laboratory in Pasadena, Calif.

The Galileo spacecraft recorded the images of Jupiter's auroras, which appear as thin patchy ribbons near the planet's poles, similar to aurora borealis near the North Pole. Images of Jupiter's dry spots, showing where its winds converge, were also record ed.

Galileo, which has orbited Jupiter since 1995, is allowing scientists to study Jupiter's atmosphere in greater detail because of its close proximity to the planet.

"Scientists are working to determine where the charged particles that make the planet's auroras come from," said Donald Hunten, UA regents professor in planetary sciences.

Scientists are also examining the planet's surface dry spots. From this they are trying to determine the conditions that will create the right formula for the enormous down drafts that have been observed in its atmosphere, Hunten said.

"We are learning how the atmosphere works," said Nalin Samarasinha, a postdoctorate in planetary sciences who works with the Galileo satellite project.

Samarasinha said scientists are studying the cloud structure of Jupiter and comparing it to Earth's atmosphere.

"It's a comparative analysis of different atmospheres," Samarasinha said. The image analysis helps scientists understand some of the phenomena that occur on both planets.

Samarasinha said when Galileo finishes its current mission of imaging Jupiter's atmosphere, it will refocus its attention on Jupiter's moons, Europa and Io.

Last month, Galileo sent scientists images of Europa. Based on those images UA scientists hypothesize conditions may be right for life on that moon.

Paul Geissler, senior research associate at the Lunar and Planetary Laboratory, said the blue color in recent close-up images is of interest to scientists.

"It means the ice is warm, in contact with water in some cases," he said. "The conclusion is Europa is warm, heated internally."

Richard Greenberg, UA planetary science professor, added Europa is an icy moon and the surface of Europa, specifically the cracks, "reminds one of Earth's Arctic ice sheets."

Greenberg said one of the hypotheses is that liquid water exists beneath the moon's ice surface, making it environmentally right for life. "It's an exciting possibility."