Water water water

There is plenty water underground on Mars!

''NASA scientists have discovered enormous underground reservoirs of frozen water on Mars, away from its polar caps, in the latest sign that life might be sustainable on the red planet.
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numerous huge glaciers up to one half-mile thick buried beneath layers of rock and debris. Researchers said one glacier is three time the size of Los Angeles in area.
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"A key question is 'How did the ice get there in the first place?'" said James Head of Brown University.

Unanswered questions also persist, Brown said, about what might be contained in the frozen water.

"On Earth, such buried glacial ice in Antarctica preserves the record of traces of ancient organisms and past climate history," he said. '' [source]

There are even surface ice-lakes:


And Mars used to have a magnetic field, just like Earth does, but:
''Deep in Mars' past, an asteroid struck the planet with such titanic force that it could've killed off the planet's entire magnetic field, according to a new study.
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One of the last giant meteors blew a hole 1,864 miles wide in the planet, creating Utopia basin in the planet's northern hemisphere. At about 4.1 billion years old, Utopia is the oldest crust on the planet that doesn't show signs of magnetism, meaning the rocks must have cooled at a time when there was no magnetic field.

Roberts and a team of researchers calculate that the Utopia impact could have done in the magnetic dynamo, which was already flagging as the planet cooled.'' [source]