This Mars-G/"Artificial"-G Experiment
After reading the artical on MSNBC, I'm a little fuzzy whether the goal is one or two part:
Mars-G or artificial-G or both.
If any part of the experiment is for determining the long-term effects of spin-G, then I think the experiment needs to be run more than once, with differing radii (and different spin-speeds).
It's too bad that most of the Mars-crowd is so hostile to ISS. This would be a perfect experiment for that environment. You wouldn't have to expend a launcher every time you wanted to run it.