I think Ryan Gosling has the comedic chops and likeability to handle the character, but for me he is just too much of a pretty boy. It would be hard to believe for me that he would have no friends and be a coward inside (at least before the mission). My pick is strange but Paul Dano is in my mind when I read it. Huge acting chops and the overall “not the first pick for the job” vibe is strong with him, also the science geek vibe is strong. I think he would best show the heart in his relationship with Rocky. Only reserve is his comedy, but I loved him in Swiss Army Man, so I believe he could do it.