DmitriDish

He was put under, into this dangerous coma (that seems to have killed his 2 crewmates), and his body was violated by more than just injection of sedatives and coma-inducing drugs. He's got all this medical equipment on him and inside him: electrodes, an IV, NG tube, catheter, and what Grace calls a "butt tube".

In the movie he's dressed in a (white, I think) flightsuit as he's rolled towards the rocket. Since the Hail Mary was assembled in orbit, I'm not sure what the timeline would've been for when he was changed out of it and into the coma suit with the zipper hood (zipper over his face like a body bag...). But given the time between his initial drugging after he ran and the launch, I imagine that there already would have been some of this medical equipment in play, forced onto him by medical professionals who may or may not have known how willing he was. The robot arms handled everything once he was on the Hail Mary, but I still wonder about Yao and Ilyukhina, how much of a role they played in transferring Grace's unconscious body onto the Hail Mary... It's upsetting, the idea of other, unknowing people on the mission being made complicit in what book Grace directly calls his "murder".

In the book he wakes up naked and exposed, just absolutely covered in tubes and wires, which is. Rough. And obviously terrifyingly vulnerable. Movie Grace has the luxury of briefs underneath a translucent coma suit, but that presents a different terrifying thing when he eventually changes out of it and takes notice of all of the things attached to and inside of his body (honestly maybe that's why he just put the stripe hoodie on and didn't change into different bottoms 😬).

For book Grace (and if you notice the "Always muscles?" note on movie Grace's Who Am I? whiteboard), he's shocked at his musculature and focuses on it in a way that makes it feel like his body wasn't particularly toned beforehand, and these muscles feel Off.

His body's functions were quite literally arrested away from him. Even his muscles themselves, that give your average able person the power to move and control themselves and where they are in space. Control of his muscles is taken by the electrodes that buzz and puppet them to keep his body toned and functional. His whole body is carefully maintained to be functional for the mission. All against his will. And his body might just look/feel unrecognizable to him because of it.

In the book the robot arm shaves his face, which oddly feels worse to ne. When he's in his coma, he doesn't even get autonomy over basic optional grooming of himself, of his own appearance. Movie Grace's hair growing out is a different horror, that he has no control over his own grooming and appearance because he's, again, put in a coma and kept alive for the express purpose of the mission, becoming unrecognizable to himself in another way. There's a reason he cuts his hair short again as he gets his shit together, it's him claiming who is and the responsibility he has to Yao and Ilyukhina and the world now that he's on this mission. He wears his own flightsuit, yellow and embroidered with his name, unaware that he never chose this.

Realistically is Rocky’s xenonite ball warm? Probably not no not at all.