Is The Martian's POOP SCIENCE Full of CRAP?

Today's episode promises to be CRAPPIER than ever - because we're talking about The Martian. That's no judgement on the movie, it's just that the film is ACTUALLY full of poop and poop science. But the question is...is the poop science actually a load of crap? Hold your nose and dive in to discover if it is actually possible for Watney to survive on Mars like the movie portrays.