The search for evidence of life in the solar system has led researchers to a new satellite--Europa, one of Jupiter's largest moons.

The Galileo spacecraft, sent out by NASA on October 18, 1989 to explore Jupiter and its surrounding moons, has detected proof of organic compounds on two of Jupiter's moons--Callisto and Ganymede. It is likely to find it on Jupiter's other two large moons--Europa and Io.

"Carbon dioxide was easily identified on Europa. We also have tentative identification of other compounds," said Karl Hibbittz, a graduate student working with the instrument team of NASA's Galileo Project.

But because organic matter alone does not provide enough evidence of life, Thomas B. McCord, planetary scientist and co-investigator on the Galileo space-craft instrument team, is researching Europa to learn more about the moon.

According to Hibbittz, there are three main factors which must be present in order for a planet to be capable of developing life: an energy source, liquid water and organic molecules.

"Carbon bearing compounds are just one leg of the triad, but on Europa we have all three," Hibbittz said.

But while the discovery of organic compounds on Jupiter may seem extraordinary, Robert A. Cameron, associate of the Harvard College Observatory, said that the finding is not unique.

Cameron said that "lots of organic molecules" have been discovered in the universe. "We know that a major satellite of Saturn is loaded with organic material, but the thing that life requires is [energy] that flows."

According to Hibbittz, because an energy source and liquid water had already been found on the moon, the discovery of organic materials--the last of the three required components for life--makes Europa unique.

"What makes Europa special are the synergistics," Hibbittz said. "Europa is closer [than Callisto] into Jupiter so it is more effected by gravitational pull, which keeps it hotter."

Hibbittz said that the source of heat on Europa is like a coat hanger being flexed back and forth.

"You know if you take a coat hanger and flex it back and forth it gets hot. The moon flexes a little [too]," he said.

Water is melted under the satellites' ice crust because of the friction from the flexing.

These discoveries were made using Near Infrared Mapping Spectrometer (NIMS), which look at the chemical composition of the surface.

Hibbittz said that this research could be used to prove whether life ever existed on Mars because of the similarity between elements found on the red planet and Europa.

But according to Cameron, the atmosphere on Mars, the first planet where astronomers found the presence of organic compounds, is too reactive.

"There may have been life on Mars at one point, but it is quite unlikely now," Cameron said.

Although scientists do not see Callisto as a possible source of life, the Galileo Project focuses on further study of the moon.

Specifically, Hibbittz's research coordinates data from NIMS with geological information to provide scientists with a more accurate perspective of the physical and chemical processes taking place on Callisto.

But while the possibility of life somewhere else in the solar system seems exciting, the discovery is nothing new for Hibbittz.

"Being in the middle of it, one loses the perspective of how exciting it is," he said.