segunda-feira, 17 de junho de 2013
Ancient craters on Mars may have been oases for life
Meteorite craters on ancient Mars may have been home to primordial life forms. Because hydrothermal systems host the most ancient known lineages of life on earth, many biologists think that the first organisms on this planet arose in hot springs. On earth these were largely volcanic systems, such as those that exist today in Yellowstone.
On Mars, the impact of large meteorites and asteroids may have been the main source for hydrothermal activity. The energy generated by these events melted surface rocks and heated water. Since it may have taken more than a million years for the center of a crater to cool, it would have been possible that a warm, moist environment could have lasted that long—more than enough time to give life a chance to evolve.
Recent studies of Sudbury crater in Canada and Lappjärvi crater in Finland have borne this out. Scientists Gordon Osinksi and Martin Schmieder have shown that the 155-mile-wide Canadian crater was home to hydrothermal activity for at least 1.6 million years and perhaps even longer. Smaller impacts creating craters 12 to 18 miles in width were ten times more common than Sudbury-sized impacts. They may also have been home to early life—though the lifespans of their hydrothermal activity—a few tens of thousands of years—may have been too short.
Craters like these on earth may have been the first—literal—hot spots of life on this planet. Cratering may have played a similar role for early Mars.
Publicado por Jorge M. Gonçalves às 11:27 da tarde