That sounds right, and if the circle is too small it will spin so fast that the crew would have inner ear problems.
You know Ben..all these fantasy freaks out there who paint pictures of colonies on Mars with all kinds of buildings all over on the surface need a good kick right in the ass.
ANYTHING that is established on Mars will have to be underground for Humans to survive at all.
That is why I laughed at the movie Martian.
But, it can be done. By the looks of it there is a lot of stone around to build shelters out in the open and cliffs to bore holes in for underground dwellings.
The first ones will have a hell of a lot of work to do though. And they better forget about scientific research till after they get underground.
They can build stone shelters and then inflate the biosphere inside after the thing is built. Or get a cave built and then inflate the biosphere inside. Course, there would be a good chance they’d find a cave?