"A Walk in the Sun" is a hard science fiction[1] short story published in 1991 by American writer Geoffrey A. Landis.
[2] The story follows Trish, the sole survivor of a terrible crash landing on the Moon.
After regaining her senses, she contacts Earth and learns that it will be thirty days before a rescue mission can reach her.
In the meantime, she depends on a wing-like solar panel to provide power to her suit's recycling facilities, and lunar night is approaching.
Due to exhaustion and loneliness, she starts hallucinating that her elder sister Karen is with her, whose death some years earlier Trish has not yet fully coped with.