[wyattpeak]

It works in principle, but it's a very big engineering task, and an enormous expense to boot. To avoid noticeably different acceleration between head and foot,* it's going to have to be substantially larger than any spacecraft we've ever built, and the biggest spacecraft we've ever built cost over $100bn. It's also going to have to withstand stresses larger than anything we've done before.

There's no reason to doubt we could do it, but it's a very big step from where we are now.

* And if we don't do that, then we stray into the realm of untested biological issues. We have no idea if people can live safely and comfortably like that.

[shkkmo]

Spinning a spacecraff is mostly hard because of the mass constraints, building a banked circular track on the moon should be much easier.

[garmaine]

It is literally two things connected by a rope. A tether-based spun spacecraft is trivial from an engineering perspective, and can have as large a radius as you need to avoid differential “gravity” effects.

[wyattpeak]

Off the top of my head:

- What material are you making the rope out of? What data do we have of that material's behaviour under tension in a vacuum?

- How is the craft connected to the rope? Is it a fixed bond or is there freedom to move? What are the tradeoffs?

- What happens when one of the two ends is accelerated? How do you reestablish a stable rotation?

- How do you manoeuvre it? Can you?

- What happens in the event of a catastrophic failure of the rope? What safeguards need to be in place?

And this is all on top of the fact that we're discussing two things connected by a rope under conditions that rope has never been tested in, doing something that's never been done. Space exploration isn't in the habit of trusting that our untested models are reliable, especially where human life is involved.