First things first - it is very noisy. I am not sure why. In space everything is basically illuminated by one giant directional light, there should be very little indirect lighting. Even with very little samples I would expect it to be more or less clean… Is there some problem?
Your image seems very overblown half of the stuff is completely white. The main cylinder of the body seems to have flat shading on, which I assume is not on purpouse.
And indeed the solar panels seem wierd. I think IRL they would be reflective and much darker in color, perhaps a little less saturated.
I would experiment a little with the camera angle as well. Maybe I am imagining things, but it seems to me that there is very little perspective in you image. What focal length are you on?
Adding some detail to the cylinder would surely help as well. The rest of the body has some nice detail, the cylinder in back seems lacking in comparison. Or at least add some more materials or some texture to it.
Hope it helps a little And hope I was not discouraging in any way. I think it could be a very good image in the end, I just try to focus on listing what could be improved.