On Earth, scientists have found organisms living in some pretty weird places.
Microscopic creatures, often living in communities that form slimy mats, have turned up deep under the ocean, where no light shines. Microbes have been discovered in cold, salty, ice-covered lakes in Antarctica. They're also in very hot, acidic water in Yellowstone National Park. (See Kidspace for May 6.) One type of microbe is so hardy it can survive heavy doses of radiation. (It was found in 1956 in a can of rotten meat that had been zapped to keep it from spoiling.)
Their homes may vary, but all these organisms need one vital ingredient: water.
So if you're looking for life in another part of the solar system, where would you go? Mars? Maybe. It has ice caps - frozen water. And data from robotic spacecraft orbiting Mars suggest that it may have ice beneath its dusty, rusty surface.
But ask Ron Greeley where he'd look, and he'll tell you he'd pick Jupiter's moon Europa any day.
"Europa has more water than all of Earth's oceans combined," says Dr. Greeley. "That's a lot of water!" Especially since Europa is only 1/4th as big as Earth. Greeley studies the geology of other planets at Arizona State University in Tempe.
Greeley and colleague Torrence Johnson at the California Institute of Technology's Jet Propulsion Laboratory (JPL) in Pasadena, Calif., are leading a team of scientists planning a mission to Europa and three other large moons of Jupiter. If all goes well, they will launch a large robotic spacecraft called the Jupiter Icy Moon Orbiter (JIMO) in 2011. Ultimately, scientists want to send special "cryobots" to Europa to try to penetrate its icy cover.
But first they have to get a better idea of how Europa is put together. Three previous spacecraft - two Voyager probes and Galileo - have visited Jupiter and its moons. The Voyagers, launched in 1977, gave scientists their first close-up views of Europa. But the two craft just flew by on their way to other planets.
Page 1 of 4