I'm not certain that is the title but the plot was about a guy who had been modified with machinery equipment to live on Mars. He was a reluctant 'experiment' at first but once he arrived he was "operational" and became perfectly suited to function and turned his back on his creators.
It appears that you have slightly mis-remembered the title. I think you are describing "Man Plus" by Frederik Pohl. It is the story of an astronaut who undergoes body modifications to enable him to live on Mars. He was originally the backup astronaut and didn't really want to do it.
The first Earthling reworked into a Martian would be Roger Torraway. Martian instead of Earthling since everything on him had to be reworked in order to survive on Mars. His organic skin is stripped off and made plastic. His eyes are replaced by large, buglike red ones. He is given wings to gather solar power, not to fly. All of which is organized and run by his friend, the computer on his back. Who was this man? What was his life like? How did he survive the transformation to become more than human and help us successfully colonize Mars?