A paper published in 2002 by University of Washington astronomer John Armstrong first presented an idea which could one day lead us to understanding how life formed on early Earth. It runs parallel to the idea that an meteorite found in Antarctica has preserved evidence of life on early Mars.
The theory posits that during the Late Heavy Bombardment, which took place approximately 3,800 to 4,100 million years ago, enough of Earth’s materials may have been ejected back in to space to collide with our moon. The LHB infers that, due to a number of impact craters dated to that time found on the Moon, Mars, Earth, Venus and Mercury would also have suffered heavy bombardment.
Armstrong’s original thought was put on hold when the question of whether any meteor ejected from Earth arriving on the moon was possible, given the speeds at which it would have been traveling.
However new research from a team under Ian Crawford and Emily Baldwin of the Birkbeck College School of Earth Sciences has added weight to Armstrong’s theory, thanks to a more sophisticated simulation of the pressures impacting a meteor making the journey from Earth to the Moon.
What they found was that, in many cases, the pressures on the meteor would have been low enough that a modicum of genetic data would have survived.The main problem was due to the lack of atmosphere around the Moon. On Earth, when an object makes for Earth, it is usually slowed down by the atmosphere.
There is no such device on the Moon, and thus Crawford and Baldwin had to decipher whether a meteorite could survive such a high-velocity impact. They performed a crude calculation to test this problem, in their most extreme test-case imputing an impact speed of 5 kilometers per second. Crawford reports that “some portions” of this simulated meteorite would have melted, but "the bulk of the projectile, and especially the trailing half, was subjected to much lower pressures."
At a lower impact velocity, of only 2.5 kilometers per second, Crawford noted that "no part of the projectile even approached a peak pressure at which melting would be expected."
But even if these samples made it from Earth to the Moon intact, are they still there today, and can we find them?
This question is the second part of a debate raging over whether early Earth data exists on the Moon. Crawford believes that, by looking for hydrates using a high-resolution IR sensor in lunar orbit, scientists would be able to detect large meteorites over a meter in size.
Similarly, a lunar rover equipped with similar sensors would be able to search on the surface.However Dr. Mike Gaffey of the University of North Dakota Space Studies department believes that any meteorites that made it to the Moon would have been shattered in to such small concentrations that it would be impossible to detect from orbit. Add to that the weathering by solar winds and a continuous rain of micrometeorites smacking in to the moon, and Gaffey’s views seem more than likely.
Crawford indeed concedes this point, and agrees that it might be necessary to dig below the surface of the moon, in an attempt to find any surviving pieces. He adds that a human presence on the moon would be the most ideal situation for this search to take place under.
Sorting through the samples discovered and then deciding what will be sent back to Earth for further study, would be a lot easier with such a human presence on the moon.
Posted by Josh Hill.
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