The last piece I wrote here, “Death on Mars”, sure got a conversation going. In a vigorous flurry of commentary on social media I was cast as either a voice of reason or a total pariah for daring to suggest that certain bold ideas for Mars exploration might face some rather nasty roadblocks. Why roadblocks? Because physics. Because biology.


As I explained in that piece, I am actually very enthusiastic about the remarkable advances being made in the space-launch industry. But if we’re going to take ideas like the large-scale human settlement of Mars seriously (putting aside reasonable concerns about our priorities while Earth is undergoing changes that challenge humanity) we need to have a longer conversation and to take some care over our enthusiasm. If only to ensure that when failures do occur we don’t give up because our expectations were too high and too unrealistic.

In that spirit (not to be taken as a rigorous analysis, but as some points to think about) here are some further questions about a human presence on Mars:

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