An exploration probe carries a simple payload - a humanoid, autonomous machine. It is equipped with everything it needs if it encounters life on other planets. Having had its system shut down now for an indeterminate period of time, quite possibly for millennia, it crashes into Equestria and boots itself up.

With no knowledge whatsoever of where it is or what kind of life forms it may encounter, it must learn of its surroundings and adapt - and should it find sentient life, whether to consider it a threat or not.