A scientist from Arizona State University estimates that it may hold twice as much water as previously thought
The crust of the planet Mars may hold two to three times more water than scientists had previously believed. This finding is based on a study by Dr. Laurie A. Leshin of Arizona State University, comparing the amount of deuterium, an isotope of hydrogen, found in a meteorite of Martian origin to the amount found in the Martian atmosphere. Her report will be published in Geophysical Research Letters on July 15.
Leshin compared the deuterium level in the atmosphere with that in a meteorite known as QUE94201, found in Antarctica in 1994 and believed to have been blasted off Mars three million years ago. Tiny water-bearing crystals in the meteorite were analyzed by Leshin on the ion microprobe instrument at the University of California at Los Angeles. These crystals contain hydrogen from the Martian interior. They revealed a smaller percentage of deuterium than current Martian atmospheric measurements.
Leshin's research shows that, in the past times, Mars had a deuterium-to-hydrogen ratio nearly double that of Earth before any atmospheric escape could have occurred. Leshin suggests that this could have resulted from loss of hydrogen very early in Martian history as a result of extreme ultraviolet radiation from the young Sun, a mechanism different than the current escape process which also favors the release of the light hydrogen molecule from the rocks, rather than that of the « heavy » deuterium isotope. Alternatively, she writes, it could imply that comets, which share the same deuterium to hydrogen ratio as Martian interior water, supplied most of the water found on Mars today.
Since Martian water originally contained higher deuterium levels than previously thought, Leshin concludes that the Martian atmosphere has lost two to three times less water through the eons in order to arrive at the isotope's current atmospheric level and that water should still exist today on Mars located within the planet's crust. In fact, evidence from this and previous research on Martian meteorites supports the idea that a significant Martian groundwater reservoir currently exists.
Just how much water is there on Mars? Leshin cautions that her research does not provide the answer to that question. Future missions to Mars will have to study the Martian soil, both in place and by returning samples to Earth, to arrive at a meaningful estimate of the actual amount of water remaining there. This evaluation is crucial when it comes to evaluate whether life (at least as we know it) has had a chance to arise on the red planet.
Taken mostly from: http://www.agu.org/sci_soc/prrl/prrl0019.html
Yves, CG Ufocom July 19th, 2000
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