The Moon's "atmosphere" is (practically) frictionless, so if you build this thing with a similarly-frictionless bearing (e.g. really strong magnets) it could th

The Moon's "atmosphere" is (practically) frictionless, so if you build this thing with a similarly-frictionless bearing (e.g. really strong magnets) it could theoretically spin near-indefinitely. Whether that's actually achievable (while still allowing people and supplies and water and oxygen and such to enter and exit) is of course another question.