Scientists create first detailed maps of dry ice deposited in Martian polar regions

September 16th, 2009 - 4:15 pm ICT by ANI  

Washington, September 16 (ANI): Scientists from the Tucson-based Planetary Science Institute have created the first detailed maps that show the amount of dry ice (solid carbon dioxide) deposited in the polar regions of Mars.

The maps reveal how the ice thickness varies with the seasons.

The maps were created from measurements taken by the Mars Odyssey neutron spectrometer, according to PSI Senior Scientist Thomas H. Prettyman.

The spectroscopy data, gathered during two Martian years, allowed Prettyman and his colleagues to accurately determine the thickness of the Martian ice caps over time.

The amount of carbon dioxide ice at the poles varies in response to seasonal changes in sunlight, and about 25 percent of the atmosphere is cycled through the seasonal caps, Prettyman explained.

“We need a detailed understanding of the present atmosphere on Mars in order to answer fundamental questions about the planet’s climate history, including whether conditions on Mars could have been suitable for life in the distant past,” he explained.

The local thickness of the polar caps depends on several factors, such as the amount of solar energy absorbed by the surface and atmosphere and the flow of warm air from lower latitudes that accompanies carbon dioxide condensation at the poles, according to Prettyman.

In the northern polar region, carbon dioxide deposition is skewed toward an area known as “Acidalia,” Prettyman observed.

Thicker carbon dioxide ice in that region may be caused by frigid winds coming from Chasma Boreale, a large canyon near the Martian north pole.

In the southern hemisphere, carbon dioxide ice accumulates more rapidly in a region known as the south polar residual cap, which is offset from the pole and contains perennial carbon dioxide ice deposits.

Prettyman and his colleagues concluded that the asymmetry in the south polar seasonal cap is caused primarily by variations in surface composition.

“The regions outside the residual cap consist of water ice mixed with rocks and soil that are warmed during summer,” he said.

“This delays the onset of carbon dioxide ice accumulation in the fall. In addition, heat stored in water-rich regions is gradually released during fall and winter, further limiting ice accumulation,” he added.

“Accurate data on the thickness of carbon dioxide ice and its distribution, as well as data on seasonal concentrations of non-condensable gases, will allow scientists to refine Martian general circulation models,” Prettyman said.

This will give them a deeper understanding of atmospheric dynamics and the planet’s climate change over time. (ANI)

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