Speculation about life beyond Earth has been fueled in recent years by the Galileo spacecraft's detailed images of Jupiter's icy moon Europa and by microscopic lumps on a meteorite, interpreted by some scientists as fossilized evidence of past microbial life on Mars. And if life on Mars proves a bust, try Europa. But, he adds, the science of astrobiology is advancing - driven by an increasing appreciation of the diversity of habitats on Earth. Wherever conditions are appropriate, life can make it, potentially. Water either is split to condense molecules or is introduced to break down molecules.
Life is in the business of capturing energy and transferring that energy into chemistry.
For a walk on the wild side, he suggests microorganisms associated with deep-sea hydrothermal vents, found along ridges where magma wells up from Earth's mantle to form new crust. Many organisms can breathe oxygen from seawater and eat hydrogen sulfide. Others eat hydrogen and breathe carbon dioxide. Now shift to Mars. While the planet has no plate tectonics, Pace says, there is water in the rock and soil that overlays Martian bedrock.