Humanity's space exploration ultimately took the form of billions of identical probes, capable of building anything (including astronauts themselves) upon arrival at their destinations. One lands in Equestria. Things go downhill from there.
Usually, we feel alone when we're by ourselves. But sometimes, the loneliest place is in the middle of a crowd. Spike has to get away, and he needs somepony to talk with him so that he can get through the evening.
The ES Harmony, the pride of Princess Twilight Sparkle and Equestria's first FTL capable starship. It is due to make its maiden voyage to travel further than anypony before it, and yet its first mission... may be its last.