NASA has recently published in Science that Mars might one have once had an ocean as large as the Atlantic, that covered 1/5 of the Martian surface, and lasted for at least a billion years.
http://www.theguardian.com/science/2015/...an-on-mars
How they figured this out is interesting. As on Earth, Martian water is a mixture of regular water and heavy water. Since heavy water is more massive, it's less likely to be lost into space. So a team of Americans and Europeans set about trying to determine how much deuterium is in the water in Mars' polar icecaps (the remains of the ancient ocean). They found a lot of deuterium, which gave them a way of estimating how much water was there originally. It calculated out to be a lot of water.
This news suggests that Mars was a lot more hospitable to life in the distant past than once thought. Water on Mars wasn't just geysers occasionally erupting groundwater, Mars was apparently once much more Earthlike.
And if there were seas on Mars for a billion years, it's interesting to speculate about whether life ever got a start there.
http://www.theguardian.com/science/2015/...an-on-mars
How they figured this out is interesting. As on Earth, Martian water is a mixture of regular water and heavy water. Since heavy water is more massive, it's less likely to be lost into space. So a team of Americans and Europeans set about trying to determine how much deuterium is in the water in Mars' polar icecaps (the remains of the ancient ocean). They found a lot of deuterium, which gave them a way of estimating how much water was there originally. It calculated out to be a lot of water.
This news suggests that Mars was a lot more hospitable to life in the distant past than once thought. Water on Mars wasn't just geysers occasionally erupting groundwater, Mars was apparently once much more Earthlike.
And if there were seas on Mars for a billion years, it's interesting to speculate about whether life ever got a start there.