Recent photos of Mars show evidence of water. However Mars is losing little water to space,so much of its ancient abundance may still be hidden beneath the surface.
Dried up riverbeds and other evidence imply that Mars once had enough water to fill a global ocean more than 600 metres deep, together with a thick atmosphere of carbon dioxide that kept the planet warm enough for the water to be liquid. But the planet is now very dry and has a thin atmosphere.
Some scientists have proposed that the Red Planet lost its water and CO2 to space as the solar wind stripped molecules from the top of the planet's atmosphere. Measurements by Russia's Phobos-2 probe to Mars in 1989 hinted that the loss was quite rapid.
Now the European Space Agency's Mars Express spacecraft has revealed that the rate of loss is much lower. Measurements from research satellites suggest the whole planet loses only about 20 grams per second of oxygen and CO2 to space, only about 1% of the rate inferred from Phobos-2 data.
If this rate has held steady over Mars' history, it would have removed just a few centimetres of water, and a thousandth of the original CO2. Thereby leaving huge amounts still available, possibly just under the surface.
Shaun A. Saunders submission
Dried up riverbeds and other evidence imply that Mars once had enough water to fill a global ocean more than 600 metres deep, together with a thick atmosphere of carbon dioxide that kept the planet warm enough for the water to be liquid. But the planet is now very dry and has a thin atmosphere.
Some scientists have proposed that the Red Planet lost its water and CO2 to space as the solar wind stripped molecules from the top of the planet's atmosphere. Measurements by Russia's Phobos-2 probe to Mars in 1989 hinted that the loss was quite rapid.
Now the European Space Agency's Mars Express spacecraft has revealed that the rate of loss is much lower. Measurements from research satellites suggest the whole planet loses only about 20 grams per second of oxygen and CO2 to space, only about 1% of the rate inferred from Phobos-2 data.
If this rate has held steady over Mars' history, it would have removed just a few centimetres of water, and a thousandth of the original CO2. Thereby leaving huge amounts still available, possibly just under the surface.
Shaun A. Saunders submission
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