I see that you are pretty new so you may not know but you don't have to upscale your art. This forum has a automatic zoom function(click to zoom in / shift+ click to zoom out). If the images gets blurry than i suggets using firefox, that is the only browser that does not blur it when you zoom in.
The astronaut looks pretty good. The proportions look right to my, and i like the antenna on the back.
The only things i dislike is that you use black outline on a smile sprite (or it is just my, i don't like black outline at all).
And that there is almost no colour variation in the suite but that may be because NASA space suites are not made to be fashonable. But you did a good job hiding that with drawing the attention to the helmet, gun and antanna.