At Discord's urging, Princess Twilight hops on through the mirror portal to Canterlot High, which had been closed for two millenia. Instead of a school, she finds herself in a cargo bay of a starship. Discord also has popcorn at the ready.
No humans. In Equestria's past, ponies exist only to serve their creators. One such pony is accidentally released from her mental chains, but how can one mare save herself and her people if she doesn't even know she's a slave?
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.
Starlight Glimmer is about to get her revenge on Twilight and her friends, she just has to stop that cyan pegasus from doing her rainbow trick. But before doing so, she receives a visit from a Doctor.
Twilight is teleported to Blood Gulch Canyon after meddling with a ship that crash landed in Equestria. She must enlist the help of the local red and blue soldiers to get home while unraveling a dark conspiracy linking her world to a shadowy agency.
While searching for his childhood friend, Thunder Gale is confronted by an ancient presence that forces him to reconcile the darkest elements of his soul, or die trying.
"An Age of Darkness will come when the lessons of Harmony are forgotten. When Equestria reaches this darkest hour, the Protectors of Equestria will return to lead the way back to Harmony." -- The Final Prophecy of Princess Flurry Heart
Princess Celestia accidentally sends Luna back to the moon. She doesn’t want to wait another thousand years for her sister to return so she requests help from the space agency to help retrieve Luna before she gets irritated.
In the far future, Princess Twilight proposes a grand scale project to resolve Equestria's looming energy crisis once and for all. Two retired princesses have some personal issues with this.
Can Twilight Sparkle figure out how to deal with the aftermath of a magical accident before it's too late? Fourth place finalist in the "Out of Time" writeoff prompt.
After seeing what happened when she accidently changed her friends destinies, Twilight is curious about about the 'what if'. Like, for example, what if Luna had ponies a thousand years ago who noticed her.
Commander John Maxon unexpectedly arrives in orbit above Equestria after a 90 year interstellar journey to Proxima Centauri in Cryostasis. John must learn to survive and inspire in an strange new world.