$10/hour is sorta typical for human experimental subject, especially if they're feeding you. The presumption is that you're basically volunteering For Science and the stipend is just to keep it from being an excessive financial hardship. Compare it to what your state pays for extended jury duty and it may look more reasonable.
My questions would be the more practical ones of just how horizontal they'd need folks to remain -- can subjects at least go to the bathroom on their own? Can reading and/or computing be made practical?
Not that I'm in anywhere near the physical condition they want for their subjects. But I'd sorta like to do something for NASA at some point in my life.