I don't remember the title or author, but it was set in an Equestria that was very old, and the sun was about to die. Celestia and Luna were the only sapient beings left, and the ponies of the world had long ago left for the stars. Luna had made a final birthday gift for Celestia by activating robots that looked like the Mane 6 so Celestia could see them again.

Does this story sound familiar to anyone?

7739704 There is a story about a dying sun:

TSupernova Daybreak

• MLP: FiM
• Dark
• Drama
• Tragedy

The sun is going supernova. Is there a way to save Equestria from the looming inferno?

• Death
• Twilight
• Spike
• Celestia

Bad Dragon · 4.4k words  ·  62  31 · 2.4k views

, but it's probably not the one you're looking for.

There is a story about recreating Mane 6:

TPrincess of Friendship

• MLP: FiM
• Drama
• Tragedy

After Twilight’s stream of successes, she’s confident that nothing can go wrong. Is she due for a lesson?

• Twilight
• Spike
• Main 6

Bad Dragon · 5.4k words  ·  290  46 · 7.9k views

, but it's probably not the one you're looking for.

Thanks-I'll check those out, but those aren't the one I was thinking of.

Some other details are that it has a space station with the artifacts of the earlier historical eras of Equestria, and the only two ponies left on Equestria (Celestia and Luna) respond to some scavengers who were trying to loot it-I forgot about them, they would be the only other sapient creatures in the story.