posted July 29, 2005
Martian Meteorites Record SurfaceTemperatures on Mars
--- Gases trapped in Martian meteorites indicate that Mars has been a cold desert for a long, longtime.
Written byG. Jeffrey Taylor
Hawai'i Institute of Geophysics and Planetology
sing published data for argon (Ar) released when Martian meteorites are heated, David Shuster (California Institute of Technology, now at Berkeley Geochronology Center, Berkeley, CA) and Benjamin Weiss (Massachusetts Institute of Technology) show that the nakhlite group of Martian meteoritesand unique Martian meteorite ALH 84001 were probablynot heated above about 0
Cfor most of their histories. This indicates that the surface of Mars has been cold for almostfour billion years. If a warm, wet environment existed on Mars (inferred from previous studies of surface features andgeochemical parameters), it occurred before four billion years ago.Reference:Shuster, David L. and Benjamin P. Weiss (2005) Martian surface paleotemperatures from thermochronology of Meteorites.
vol. 309, p. 594-597.
Soaking Wet, Bone Dry Mars
limate change on Earth is often in the news. Climate specialists worry about swings in global temperatures of severaldegrees Celsius. This does not sound like much, but it is enough to cause ice ages sometimes and widespread shallow seasat other times. But those changes are nothing compared to what the planet Mars seems to have experienced. Mars isdecorated with huge channels eroded when vast quantities of water flowed through them. Oceans may have existed in thenorthern plains. Valley networks decorate the planet's surface. Yet now it is a dry, cold place. The daily averagetemperature at the equator is an ultra-nippy 60
C below zero. Its monotonous dry climate has been enlivened occasionally by water seeping from the sides of impact craters, and changes in the planet's tilt may have moved glaciers from thecurrent poles to more equatorial regions, but basically it has been colder and drier than anyplace on Earth. Yet at sometime in the past, probably billions of years ago, Mars was a much warmer and wetter place.
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