The Man Who Hated Mars by Randall Garrett
To escape from Mars, all Clayton had to do was the impossible. Break out of a crack-proof exile camp–get onto a ship that couldn’t be boarded–smash through an impenetrable wall of steel. Perhaps he could do all these things, but he discovered that Mars did evil things to men; that he wasn’t even Clayton any more. He was only–THE MAN WHO HATED MARS.