If you're interested in the details of what goes in to developing rotors for a helicopter for an atmosphere we've never built in before you should check out this talk: https://doi.org/10.52843/47ly7q

Thanks! In scaling up the fragility of the material seems very likely to be a big factor, cube-square law and so on. I wonder if there’ll be physical testing of proposed designs, are there even near-vacuum wind tunnels?

A lot of that talk compares theoretical results with experiments in a low-pressure wind tunnel (see e.g., the slide at this point https://cassyni.com/events/6GYLBKG5pBd4su8dm9A9FB?t=255.0s for a reference).

It's quite a simplistic (2d) setup however. I'm not aware of any more complex experiments.

You can see how the whole thing would fold up in the linked article, there's an image from the white paper that shows MSH fitting into the same size aeroshell Mars Pathfinder used. It would run on solar power and recharge itself, just like Ingenuity.

Thanks, for some reason I had a brain fart and thought it’s one giant rotor.

Also, the rotors would blow away dust on the landing site, which may be a problem if you want to research dust, but may be an opportunity if you want to see what's beneath it.