This was a novel, in paperback, and I don't remember the title, author, or cover art.
What I remember about the story includes words such as:
- yellow energy
- needles (small attack spaceships)
and the story was about an expedition to a rogue planet, far out in the middle of nowhere, with one city, with extremely advanced technology, so advanced that almost none of it was understandable by the various people.
The expedition was several ships, including one huge ship, and they went through some type of gates that transferred the ships across many light years each time.
Two of the main characters were a historian who was previously a commando, and a pilot, and by the end of the story they decided to marry.
Another main character was an artist, who discovered an artifact in one of the buildings, which none of the scientists were able to discover.