The writer of the novel, Andy Weir, first published his book for free on his own site, after being declined by several publishers. Later the book was sold on Amazon for the minimum price of $0.99.
The author of The Martian, Andy Weir, personally created software to calculate the ship's arrival times (on Earth and on Mars) down to the exact minute in his novel. You can look up the interview where he explains this online.
This will mark the second time Jessica Chastain and Matt Damon have worked together on a space related film. The other film being Interstellar (2014). Although they shared no scenes together.