[tillinghast]

> Astronauts would never be as stupid as they're depicted in that film, things like "oh gee I think I'll take my helmet off around all this potential biohazard."

My head-canon explanation for this is that a good portion of the crew specifically were not astronauts -- they were experts in their field (geology, anthropology, etc.). And true-to-form, they were dismissive of other experts telling them NO, NO DO NOT REMOVE YOUR HELMET. And once the first few were exposed the others decided well, if there's a problem with it we're already screwed anyway.