The problem, Do says, is how to supply and maintain the systems needed to keep the crew alive. The outpost would need to be regularly resupplied with spare parts to keep functioning for an indefinite amount of time. As the outpost grew — and the Mars One plan calls for four people to be sent every two years — it would need even more parts.

“You can’t order one from [the] local spare parts store because it’s just not there, so either you bring it along with you initially, or pre-place it before you get there,” Do says. “Or you have to wait for your next launch opportunity, which is 26 months from the time that you first get there.”

All that resupplying would be expensive, and Do says Mars One hasn’t factored this into its projected budget.

The MIT study also calls into question other parts of the Mars One plan, such as the projected oxygen levels in the outpost. The MIT study concluded that Mars One hadn’t factored in the need for a device to remove oxygen. Bas Lansdorp, Mars One’s CEO, told Popular Science that devices to remove oxygen are common in places like hospitals, but Do says testing them in space — let alone Mars — is an entirely different proposition.