Just do what i did, and go into the game files, and make it so you have completed all the achievements. Its a lot easier than actually finding the space ponies, and its what a true pink space pony would do.
Why even have the achievements in the game if you just edit the file to say you got them all? Is it really that important your list is checked off, rather than have those that you actually managed to get on your own?
When I got the Space Ponies I had no clue what had happened for me to get them... I never would have equated it to exploring a planet, I was just watching a fleet prepare to jump when I got it. /shrug