Mars Emerging from Ice Age, Data Suggest

Scientists have suspected in recent years that Mars might be undergoing some sort of global warming. New data points to the possibility it is emerging from an ice age.

NASA's Mars Odyssey orbiter has been surveying the planet for nearly a full Martian year now, and it has spotted seasonal changes like the advance and retreat of polar ice. It's also gathering data of a possible longer trend.

There appears to be too much frozen water at low-latitude regions -- away from the frigid poles -- given the current climate of Mars. The situation is not in equilibrium, said William Feldman of the Los Alamos National Laboratory.

"One explanation could be that Mars is just coming out of an ice age," Feldman said. "In some low-latitude areas, the ice has already dissipated. In others, that process is slower and hasn't reached an equilibrium yet. Those areas are like the patches of snow you sometimes see persisting in protected spots long after the last snowfall of the winter."

Frozen water makes up as much as 10 percent of the top 3 feet (1 meter) of surface material in some regions close to the equator. Dust deposits may be covering and insulating the lingering ice, Feldman said.

Feldman is the lead scientist for an Odyssey instrument that assesses water content indirectly through measurements of neutron emissions. He and other Odyssey scientists described their recent findings today at the fall meeting of the American Geophysical Union in San Francisco.

"Odyssey is giving us indications of recent global climate change in Mars," said Jeffrey Plaut, project scientist for the mission at NASA's Jet Propulsion Laboratory.

High latitude regions of Mars have layers with differing ice content within the top 20 inches (half-meter) or so of the surface, researchers conclude from mapping of hydrogen abundance based on gamma-ray emissions.

"A model that fits the data has three layers near the surface," said William Boynton of the University of Arizona, Tucson, team leader for the gamma-ray spectrometer instrument on Odyssey. "The very top layer would be dry, with no ice. The next layer would contain ice in the pore spaces between grains of soil. Beneath that would be a very ice-rich layer, 60 to nearly 100 percent water ice."

Boynton interprets the iciest layer as a deposit of snow or frost, mixed with a little windblown dust, from an era when the climate was colder than nowadays. The middle layer could be the result of changes brought in a warmer era, when ice down to a certain depth dissipated into the atmosphere. The dust left behind collapsed into a soil layer with limited pore space for returning ice.

Other Odyssey instruments are providing other pieces of the puzzle. Images from the orbiter's camera system have been combined into the highest resolution complete map ever made of Mars' south polar region.

"We can now accurately count craters in the layered materials of the polar regions to get an idea how old they are," said Phil Christensen of Arizona State University, Tempe, principal investigator for the camera system.

Temperature information from the camera system's infrared imaging has produced a surprise about dark patches that dot bright expanses of seasonal carbon-dioxide ice.

"Those dark features look like places where the ice has gone away, but thermal infrared maps show that even the dark areas have temperatures so low they must be carbon-dioxide ice." Christensen said. "One possibility is that the ice is clear in these areas and we're seeing down through the ice to features underneath."

Thanks for this. This is really interesting because it does suggest a change in the sun's intensity.

For the past century or so, the North Atlantic region has been emerging from the "Little Ice Age." The causes are not well understood, and I say "causes" because there are probably several, but of great interest is whether changes in solar radiation might be the major cause.

The primary approach to that question is to determine if the cooling was global. Unfortunatly, there is not much in the way of worldwide climate documentation. A lot of evidence points to a global cooling but there is enough counterevidence to make the matter ambiguous.

So, if the cooling turns out to be not merely global, but solar systemwide, this could nail it.

So, if the cooling turns out to be not merely global, but solar systemwide, this could nail it.

Of course not. If every planet in the solar system is getting warmer it is purely coincidental. Earth is getting warmer because Americans drive SUVs. End of story.

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