I started work on this project years ago and came back to it from time to time. I have many sketchbook pages dedicated to different ideas and designs relating to it in one way or another. I was working out the proportions of the armature around this time. You can see I originally envisioned the backpacked being more like a jet engine, but pulled that back to a more realistic design later on.
I also pulled a lot of space and astronaut images as inspiration from different sources. Sadly, I don't remember the book I scanned these from. You can definitely see some areas I looked at when creating the suit for my character. You can click the individual images to see them larger.