Mars' missing air might just be hiding

Rather than having had its air knocked out into space, Mars might just be holding its breath. New findings suggests the missing atmosphere of Mars might be locked up in hidden reservoirs on the planet, rather than having been chafed away by billions of years' worth of solar winds as previously thought.Combining two years of observations by the European Space Agency’s Mars Express spacecraft, researchers determined that Mars is currently losing only about 20 grams of air per second into space.Extrapolating this measurement back over 3.5 billion years, they estimate that only a small fraction, 0.2 to 4 millibars, of carbon dioxide and a few centimeters of water could have been lost to solar winds during that timeframe. (A bar is a unit for measuring pressure; Earth’s atmospheric pressure is about 1 bar.)According to the "warm and wet early Mars" model, liquid water once flowed on the red planet’s surface.

Evidence from channels and gullies recently spotted on Mars suggest the water layer might have been more than half a mile deep in places. For Mars to keep that much water in liquid form, the planet must have had a much higher atmospheric temperature, which scientists think was made possible by a strong greenhouse effect in the planet’s past.Mars' atmosphere must have been between 1 to 5 bars to maintain that kind of greenhouse effect, scientists think. But Mars’ atmospheric pressure today is only a small fraction of that—about 0.008 bars, or about 0.7 percent of the average surface pressure at sea level on Earth.

View: Full Article | Source: Space.com