WORLD> Europe
|
WORLD> Europe
|
|
Bits of Ancient Earth Hidden on the Moon
(Agencies)
Updated: 2008-06-26 21:19 Some scientists believe that at least one meteorite found in Antarctica preserves evidence of ancient life on Mars. Now, work by a team of English scientists reinforces an earlier suggestion that evidence of life on the early Earth might be found in meteorites on the moon. The original idea was presented in a 2002 paper by University of Washington astronomer John Armstrong, who suggested that material ejected from Earth during the Late Heavy Bombardment (a period about four billion years ago when the Earth was subjected to a rain of asteroids and comets) might be found on the moon. Armstrong's suggestion was interesting, but whether a meteor ejected from the Earth might arrive intact on the moon remained an open question. New research by a team under Ian Crawford and Emily Baldwin of the Birkbeck College School of Earth Sciences used more sophisticated means to simulate the pressures any such terrestrial meteorites might have experienced during their arrival on the lunar surface. This confirmed Armstrong's hypothesis. In many cases, the pressures could be low enough to permit the survival of biological markers, making the lunar surface a good place to look for evidence of early terrestrial life. Any such markers are unlikely to remain on Earth, where they would have been erased long ago by more than three billion years of volcanic activity, later meteor impacts, or simple erosion by wind and rain. Crash landings Given that material from early Mars has been found in meteorites on Earth, it certainly seems reasonable that material from the early Earth could be found on the moon. Indeed, Armstrong's paper estimated that tens of thousands of tons of terrestrial meteorites may have arrived there during the Late Heavy Bombardment. However, there is a problem: The moon lacks any appreciable atmosphere. Meteorites arriving on Earth are decelerated by passing through our atmosphere. As a result, while the surface of the meteorite may melt, the interior is often preserved intact. Could a meteorite from Earth survive a high-velocity impact on the lunar surface? |
