Pretty lame reason for not having a fortress in space. And he blew a star? Huh?
My impression of this story is that it's basically a vehicle for summarizing all the significant Fortress of Solitude stories in one location. It's a bit difficult to read the narration box, but it looks like the blowing a star thing happened in
Action 261. And we're reading a one page summary of the events, not the complete story, so we don't know the details.
Action 261 was published in 1960, right on the cusp of the Silver Age, but probably still taking place in a crazy 1950s reality. Most likely it was "Superman's Fortress of Solitude" which was written by Jerry Siegel and illustrated by Wayne Boring.
At any rate, I really like the big scenic spreads by Ross Andru - very nice!