The orbiter found a cap of ice covering atop a series of layers that alternate between ice-rich and dust-rich bands, suggesting relatively recent environmental and climate changes. “At the north polar ice cap over the last 100,000 or so years, there’s been a really dynamic history of changes reported in layers of ice much like we would determine Earth’s climate change and looking at a core of ice from Greenland,” said Scott Murchie, of Johns Hopkins University’s Applied Physics Laboratory, who serves as lead scientist for MRO’s imaging spectrometer. The imaging spectrometer also spied a wide range of mineral-rich clays on Mars in a region known as Mawrth Valles; some rich in iron while others nearby contained aluminum. “Clay tells us that the surface was wet, and differences in the mineralogy tells us how the environment may have been different from place to place,” Murchie said, adding that differences in clay composition can indicate variations in water temperature, salinity and other characteristics in the site’s past. “What this is telling us is that on length scales of just a few hundred yards, the conditions were varying significantly enough that entirely different kinds of minerals were forming. What impresses me most is that this is really a system of gullies, this is a complex landform,” said Alfred McEwen, HiRISE principal investigator at the University of Arizona, adding that they may have been carved by flowing water in the past. “The big question here is, ‘Is water seeping to the surface today?’ and right now we don’t have a smoking gun.” MRO has been circling Mars since it arrived at the red planet in March, but only settled into its final science orbit last month. Launched on Aug. 12, 2005, the spacecraft carries enough fuel to last through 2018. Full science operations will begin Nov. 7 after the red planet has passed behind the Sun. http://www.msnbc.msn.com/id/15293429/ 2006 Space.com
