How scientifically accurate is The Martian?

The release of Ridley Scott's space hit coincided with the discovery of water on the red planet, which leads us to ask - how realistic is it, technically? A leading aerospace engineer offers his opinion

Overall it's a very good movie, and while there are mistakes in it, it is the first genuine Mars movie. It is the first movie that attempts to be realistic and that is actually about human beings grappling with the problems of exploring Mars, as opposed to various movies set on Mars that are essentially either shoot 'em ups or horror films. It does not engage in fantasy: no monsters, no magic, no Nazis. However, there are a number of technical mistakes.

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