Should we speculate on its function?
It looks modular to me. The streamlined control bridge can be separated from the rest of the body. Those bulges seen below the ship are fuel tanks.
I think that dish is part of this ship's primary function. Maybe it's a listening vessel. Maybe those fuel bladders, of which I can see three on the starboard side, are used for micro-jumps within the system.
Maybe it's used to detect piracy?
Or, maybe the world in this system is balkanized, and this is a vessel that spies on the other countries, especially their bases within the solar system?
From the windows, I'd speculate that it's not a big vessel. 100 tons or less. Heck, it might not even have a J-Drive and designed for intersystem use only.