 Exposure to fire typically causes her to lose control over some of her powers like Telepathy, Invisibility, Intangibility, Martian Vision, and Flight which leaves her very faint and weakened.It was revealed, during the "Trial By Fire" storyline, that the Martian weakness to fire is an inbuilt psychosomatic effect, placed in the Martian race long ago by the Guardians of the Universe.The purpose of this was to prevent the Martians from reverting to a previous state in which they were highly aggressive, on the verge of interstellar conquest, and required flames and the psychic suffering of others in order to reproduce.