The movie understates them. I vehemently disagree with this, though:
Martian gravity is roughly one-third the gravity on Earth. Experiments on the International Space Station show that plants, animals and humans all suffer in weightlessness, but no one knows how living creatures will fare in reduced gravity.
“Maybe plants will be happy, maybe animals will be happy, maybe humans will be happy,” McKay says. “Or maybe not.” The effect of reduced gravity isn’t easily tested ahead of time and though probably not a huge problem, it could be a “showstopper,” McKay says.
It is easily tested ahead of time. Stop wasting money on a giant rocket and build a gravity lab. The fact that we’re not is one of the strongest indicators that neither NASA or Congress are serious about Mars.
[Update a few minutes later]
Barriers to colonizing Mars. I don’t buy this number for a minute, though:
NASA’s current Mars mission concept would set us back about $50 billion over the course of a decade, or about twice as much as the moon program cost between 1962 and 1972.
First, in current-year dollars, we spent more like a hundred billion on Apollo (the $25B is in sixties dollars). But they’re probably going to spend that much just on SLS/Orion, without any actual Mars hardware.
Don’t worry, Matt Damon won’t get stranded on Mars, because NASA can’t get him there.