228
A City on Mars: Reality kills space settlement dreams
(arstechnica.com)
This is a most excellent place for technology news and articles.
The point isn't that Mars is somehow less vulnerable to asteroid impacts than Earth, it's that asteroids aren't likely to hit Earth and Mars at the same time.
He thought they didn't happen on Mars for some reason and that he wanted to colonize it to hopefully abandon Earth altogether because we have apparently no hope here whatsoever and the planet isn't salvageable anyway.