perfidy

Hiding their air from us, apparently. New measurements and calculations from the orbiting Mars spy satellites indicate that Mars is losing about 20 grams of atmosphere a second. Which is not a whole hell of a lot. Even adding it all up over the course of billions of years, its still not a whole hell of a lot.

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.

Which means that either Mars never had the thicker, wetter atmosphere we think it did in the past, or else that atmosphere was not blown away atom by atom by the solar wind as we thought it did. Either way, something we though was so, weren't. If Mars did in fact have that thick atmosphere, it must be sequestered away somewhere in, around, or in the pockets of the planet. Which is a positive thought for all those budding junior scientists with their home terraforming kits. Martian air, perhaps hidden in underground reservoirs, or bound up in the crust or whatnot, would at least theoretically be amenable to be reintroduced into the atmosphere. Unless a third theory is true - that Mars' atmosphere was blown clear off the planet by a large meteor strike. So, to sum up, Mars doesn't have air, and is losing it slowly. It may or may not have air hidden. Mars may or may not have had a thick atmosphere in the past. Mars may or may not have been hit by an atmosphere-stealing asteroid. See how our knowledge grows?

[wik] I find it interesting, btw, that catastrophic explanations for what we see in the solar system are becoming more common.