While reading the latest thinking on the past climate of Mars (20 October, p 44), I found myself wondering whether the planet has always been in its present orbit.
If it had a warmer, wetter climate 3.6 billion years ago, could it have been closer to the sun then? Could Mars have somehow been ejected into a new orbit at some point, causing it to lose its atmosphere and its water to freeze? Has anyone run simulations along these lines?
And if there is no life on Mars, will we still be determined to build a colony there?
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