Another Option
That our hypothetical structure is an alien. Not a sentient one, but a very large plant or animal not from earth. In this setting, the bright spot is a shell against hard vacuum that also collects solar energy. The shell is created with polygonal plates (like an urchin) that almost look artificial. Below this caprice are roots/tendrils that tap the water at depth. Waste product is expelled into space.
How important to visit this scenario? Great scientific opportunity with questionable economic value (or value not immediately apparent).
How curious are we?