Lighting is very weird. I don't know exactly what but I will try: The scene is too evenly lit. It's visibly not part of the background photo. Reduce secondary bounces because in space there is not much from what light could bounce in the shadow. That means that shadows are not black enough. As far as I can see, you don't have ambient occlusion. Turn it on because it adds a great deal of realism.
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dunno if this picture might help.
And I found some external links on it that can help you in modelling the details:
http://www.w-bench.com/index.php?div=stnet&tmp=op&data=database&page=7&col=dark
Next, more details
Now the materials.;)
Not sure about reflections though... maybe blur them out.
I've reduced the reflection somewhat. I did not like that too well.
If the object can use someone, short PM
The background is, by the way, 3d and no image.