Carnival

Mars shows signs of recent activity
Carbon dioxide measurements suggest liquid water and volcanoes in past 100 million years
By Ron Cowen
Web edition : Thursday, September 9th, 2010
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MARS PHOENIX LANDERA new analysis of carbon dioxide gas sampled in 2008 by NASA's Mars Phoenix Lander, shown in this self-portrait taken by a camera on the lander, suggests that the Red Planet may have been an active place with volcanoes and liquid water during the past 100 million years.JPL/NASA, University of Arizona, Texas A&M University
New evidence suggests that Mars was much more active in the relatively recent past, with volcanoes erupting and water flowing on its surface within the past 100 million years.
The findings are based on the most precise measurements ever taken of carbon dioxide in the Martian atmosphere, recorded by NASA’s Mars Phoenix Lander during its five months of operation in 2008. Because carbon dioxide gas reacts strongly with both water and silicate rock, measuring the relative proportions of different isotopes of carbon and oxygen in the Martian atmosphere provides a record of the history of both materials on the planet.  Paul Niles of NASA’s Johnson Space Center in Houston and his colleagues report the findings in the September 10 Science.
The carbon dioxide measurements “may be the most profound result to come out of the Phoenix mission,” comments Bruce Jakosky of the University of Colorado in Boulder, who was not involved in the study.
Over time, carbon dioxide exits the Martian atmosphere because the planet’s low gravity and small magnetic field can’t provide a strong enough anchor. During this process, the lighter carbon isotope, carbon-12, in the carbon dioxide escapes more quickly than the heavier isotope, carbon-13, and the ratio of carbon-12 to carbon-13 diminishes. Yet Phoenix found that the relative proportion of carbon-12 to carbon-13 was not smaller, as if the supply of carbon dioxide now in the Martian...