Kris Overstreet has completed (except for epilogues) a very well done My Little Pony/the Martian crossover.
https://www.fimfiction.net/story/396744/the-maretian
"The last man on Mars sat in his habitat, all alone, and typed.
So that’s the situation. I’m stranded on Mars. I have no way to communicate with Hermes or Earth. Everyone thinks I’m dead. I’m in a Hab designed to last thirty-one days.
...
There was a knock at the door."
https://www.fimfiction.net/story/396744/the-maretian
"The last man on Mars sat in his habitat, all alone, and typed.
So that’s the situation. I’m stranded on Mars. I have no way to communicate with Hermes or Earth. Everyone thinks I’m dead. I’m in a Hab designed to last thirty-one days.
...
There was a knock at the door."