Complex sentence: His injury proves relatively minor, but with no way to contact Earth, Watney must rely on his scientific and technical skills to survive, growing potatoes in the crew's Martian habitat (or Hab) and burning hydrazine to make water.
Split into simpler sentences: His injury proves relatively minor, but with no way to contact Earth, Watney must rely on his own resourcefulness to survive. Watney begins growing potatoes in the crew's Martian habitat (or Hab) and burns hydrazine to make water.