[cjensen]

Without a magnetic field, there is way too much radiation on the surface of Mars. A colony would pretty much need to live underground. If you are going to live underground on a planet with unusably-thin air, why not live on the Moon instead?

[greglindahl]

Instead of just asking the question that many people think they have answered, why not say what you don't like about their answers?

For example, Elon's speech about Mars colonization gives one answer. Maybe you've got great reasons to disagree with him. Maybe there's someone else you'd like to reply to?

(Hint: folks advocating for Mars think the atmosphere is not unusable.)

[cjensen]

Not quite sure what you mean: I was responding to a question asking why it would be nice to have a liquid core. In other words, I was commenting on the radiation question.

To hide from Radiation, one plan is to have 16 feet of soil on top of the habitat [1], and limit outdoor time to just 2 hours a day. Given those levels, I'd argue that it would make better sense to build entirely underground on the Moon. The Moon has a shallower gravity well, much stronger solar flux for power, and is much closer for resupply.

[1] http://www.space.com/21813-mars-one-colony-space-radiation.h...