Re: I'm planning aa marathon
I'd give "The Right Stuff" a miss and read the book if I was you. I really enjoyed that the first time round and, years later, its still good value. OTOH I was really disappointed by the film: I saw it on first release and never want to see it again - far too artsy and not nearly enough Right Stuff for my taste.
Read the book and then follow it up with Michael Collins's "Carrying The Fire".