> once you're on the surface of Mars, things get a lot easier Yes, thanks for pointing that out to me. But TFA notes that (a) the Earth's atmosphere, and (b) t

> once you're on the surface of Mars, things get a lot easier Yes, thanks for pointing that out to me. But TFA notes that (a) the Earth's atmosphere, and (b) the Earth's magnetic field, contribute nearly all of our shielding from both solar and cosmic radiation. Living in a cave on Mars might shield you from solar flares; but it will provide quite limited protection from gamma rays. Mars has a much weaker magnetic field than Earth (Wikipedia says there's no evidence of any magnetic field at all).