A quick run down on how i light up and composite (super reduced node setup though) my space renderings.
Make sure your albedo values of your surfaces are roughly where they should be (white paper has a value of ~0.65, there should not be a lot in you scene which is brighter), otherwise your result will be a completely white image.
Visit me on Artstation: artstation.com/linolafett
I am somtimes on Twitter: twitter.com/linolafett
