Alright! The first glaring issue I've noticed is that she is not casting shadows on her scarf.
Since this is outer space with little atmosphere as you've mentioned, and with her being this close to the camera, surfaces on her body that's angled away from the light source should not be lit unless light bouncing from different surfaces hit her body. Such as her right shoulder pad's side surface being lit by the light bouncing off from her scarf.
Apart from that, the moon behind her, provided it's not emitting any light/glowing, looks really flat. If it's being lit by the same light source that's illuminating our character, it should be lit according to its geometric anatomy. Since it's a sphere, it should be lit like a sphere.
However, if the moon behind her is indeed glowing, then, based on something I learned from stargazing and photography, all those stars shouldn't be as visible as they are. Maybe turn down their twinkles by 50%? It's because the glow emitted by the moon, and the fact that the moon is really HUGE, overlaps the light emitted by the stars. Apart form that there should be a visible glow around it.
Overall, the general problem in your piece is there are so many contrasting elements in the image, it's quite hard on the eyes and harder to identify the focal point. So apart from the fix I did, here's a suggestion to tighten up the comp by adjusting the lighting on her.
Hope that was helpful 
PS
I am sorry for this long overdue reply. I wanted to work on this critique when you replied to my previous comment, unfortunately, I was swamped with work the entire week.
