If carbonate minerals were formed on the Martian surface by chemical reactions between water and the atmosphere, the presence of these minerals would be a clue that water had been present for a long time-perhaps long enough for life to have developed. We know that most of the current Martian atmosphere consists of carbon dioxide.
Knowing where carbon is present and in what form would tell us a lot about where life might have developed. The element carbon, for instance, is a fundamental building block of life. NASA will also look for life on Mars by searching for telltale markers, or biosignatures, of current and past life. Perhaps tiny, subsurface microbes on Mars could use such energy sources too. Chemical and geothermal energy, for example, are also energy sources used by life forms on Earth. Here on Earth, we find life in many places where sunlight never reaches-at dark ocean depths, inside rocks, and deep below the surface. Therefore, future missions will also be on the lookout for energy sources other than sunlight, since life on the surface of Mars is unlikely given the presence of "superoxides" that break down organic (carbon-based) molecules on which life is based. In addition to liquid water, life also needs energy. We know that water ice is present at the Martian poles, and these areas will be good places to search for evidence of life as well.
Recent data from Mars Global Surveyor suggest that liquid water may exist just below the surface in rare places on the planet, and the 2001 Mars Odyssey will be mapping subsurface water reservoirs on a global scale. Perhaps there might also be some current "hot spots" on Mars where hydrothermal pools (like those at Yellowstone) provide places for life. On Mars, we will therefore search for evidence of life in areas where liquid water was once stable, and below the surface where it still might exist today. It is likely, though not certain, that if life ever evolved on Mars, it did so in the presence of a long-standing supply of water. On Earth, all forms of life need water to survive. The search begins with determining whether the Martian environment was ever suitable for life.
HOW MUCH DMG DOES EXPLO FO FULL
Credits: NASA/JPL-Caltech/University of Arizona Download full image ›ĭuring the next two decades, NASA will conduct several missions to address whether life ever arose on Mars. Some larger channels on Mars that are sometimes called gullies are big enough to be called ravines on Earth. This image shows many channels from 1 meter to 10 meters (approximately 3 feet to 33 feet) wide on a scarp in the Hellas impact basin.
0 kommentar(er)
