a few suggestions here and there
You have the idea of spatial concepts down. I like the cow in the background. Some improvements might be adding some shading from the glow in the background. It's a quick throw together, you're making sure to tell us that, which I can respect. For something quick, it's very cute, I like the detail you put in.
If you wanted to refine it, fluff it up a bit, and resubmit, I think it could make a ten. shading is important, especially since it looks like, to me, that you added in the stars from a realistic photo or template? Glow from the tractor beam would be great, giving the idea of 3d to the cow and the alien and the ship. You have an idea of it, you outlined the folds pretty well :)
Anyway, good job on a cute artwork, and this picture has potential if you wanna work on it some more.