Well lets jump right in.

Right off the bat, I pick up on the scene you are trying to convey to the viewer. The spotlights and the flare are great indicators of a classic rescue at hand. The hostile terrain with its dark and low-lit approach, really give me a strong feeling for the tension, as if I could almost relate to the people that re stranded. The large planet in the background with its moon(s) provide just the right amount of contrast to keep the viewers attention and add subtle elements to help the viewer figure out the story behind the piece.

Your level of detail is incredible. I can see it in every little corner I look into on this piece. It's great to see someone who goes the extra step in their work. Take for example that faintest of halos around the flare, the tiny building lights, or even the frost on the branches. It's things like this that really push a piece to the next level.

Now setting aside what I just mentioned, lets consider some areas that could use some improvement.
-- _{Lighting. While I think you have an understanding for lighting that goes beyond the average artist I think that sometime an extra technical eye can really be us use. Your lighting on the large planet and moon are consistent with each other, but its does not seem to translate over to your rescue scene. I can't really place a definitive light source, not that this overly critical, but some viewers may question it.}
-- _{Your rescue craft, while being well portrayed and artistically displayed seems to be a bit cliche in design. We know that a sphere serves as a very utilitarian shaped object, but when used in this picture it seems to steel a bit of your creative spirt. When you approach spacecraft design, be very open minded and be willing to consider odd designs. Since it does not exist, that is your chance to push its design without people rejecting it.}
-- _{Also, the flames coming from behind the craft as propulsion seem a bit far fetched. The craft closest to the ground appears to be going the same speed as the ones far off the ground because its jet looks just as "full-blast" as the others so to speak . Consider maybe changing the flame color to something more futuristic. That orange color seems to much like a combustion engine of today.}
-- _{Another thing that sort of bothers me is the way you aligned the foreground and the middle-ground. In the foreground you have this flat ground with some rocks and tree, but then behind those you have a very tilted landscape that does not seem to match. It kind of looks as though one half of the terrain is just sliding away. This creates a good visual tension but is also a bit distracting.}

Other then what is mentioned above, I think the piece overall is great. Keep up the good work.