From back cover of Tor paperback May 1993:

Sam Houston Kelligan had from boyhood known that he would someday fly to Mars. But what children dream of is often far different in reality from what one could ever imagine. Having been chosen as one of a select crew Kelligan does go to Mars, only to be marooned with a crippled spacecraft, afflicted with a debilitating illness, and abandoned by crewmates. Aided by one brave woman Kelligan must somehow find a way to survive the rigors of the hostile planet and return to Earth before the members of the first manned mission to Mars have all succumbed.