The 38% gravity may be an unsurmountable problem: The only way we know how to make artificial gravity is to spin a wheel and live on the inside rim. But how do you combine full "gravity" from a wheel with 38% real gravity from Mars? In space, you just have to spin your wheel and everything is fine. We need some data with a 0.38 G wheel in orbit to see if 38% gravity is enough to avoid the brain damage and other bad effects of weightlessness.

If it is, then Mars could be a good one-way destination for the retired.