Study suggests Mars getting warmer

WASHINGTON -- Vast fields of carbon dioxide ice are eroding from the poles of Mars, suggesting that the climate of the Red Planet is warming and the atmosphere is becoming slightly more dense.

Experts say that over time such changes could allow water to return to the Martian surface and turn the frigid planet into a "shirt-sleeve environment."

Michael A. Caplinger, a scientist with Malin Space Science Systems, said that if the rate of carbon dioxide erosion from the Mars poles continues for thousands of years, "then it could profoundly amend the climate of Mars."

"You would go from having to wear a spacesuit to just wearing a coat and an oxygen atmosphere," said Caplinger.

Caplinger is co-author of a study appearing in the journal Science that analyzes photos of Mars taken by an orbiting spacecraft. The photos were taken in 1999 and in 2001, a period of time that represents one Martian year. Mars is farther from the sun than the Earth and it takes the Red Planet about 23 months to complete one year, a single solar orbit.

Observers have long known that in the Martian winter there is a snow of carbon dioxide caused as temperatures plunge and the gas freezes out of Mars' thin atmosphere.

Not a seasonal change

But the new study suggests that a dense cap of frozen carbon dioxide thought to be permanent at each of the Mars poles may not be all that permanent, said Caplinger.

"It is eroding away at a rapid pace and is going to continue to do that," said Caplinger. "This is not a seasonal change."

He said the photos suggest that the polar caps are dense slabs of frozen carbon dioxide that may have been deposited over centuries.

The key clue, he said, comes from examining the light patterns on pits at the Martian south pole. Comparing pictures taken a Martian year apart show that the pits are getting wider and deeper as a result of the retreat of the carbon dioxide ice, said Caplinger.

As the C02 ice erodes, it adds carbon dioxide to the Martian atmosphere, causing the "air" to get thicker over time. This would enable the planet to hold more of the sun's heat and, perhaps, eventually warm the whole planet enough for water to return to the surface.

Caplinger said it is not known if there is enough carbon dioxide in the polar caps to bring about such an atmospheric change.