One of the first things Alicorn Princess Twilight does is set out for a space program, 100 years later, that same program takes Equestria past the moon and even to their former homeworld, Equine.
This is the story of Starsky, a stallion part of a crew in the CSA, Celestia Space Association/Civilian Space Agency. And on his crew's anniversary of thier first assignment, they realize things will be much more different than last year.