Design aspects of Alien were divided among various artists, and French illustrator Jean Girard aka Moebius was tasked with designing the outfits for the film, worn both internally and externally by the Nostromo crew. His spacesuits went through an evolution, dictated by the changing nature of the stormy planetoid they landed on according to various script drafts. Early concepts of what would be later designated as LV-426 in Aliens had the planetoid with unbreathable air but air pressure similar to Earth, so the crew members who ventured outside only needed air masks. This would later be changed so that they would require full pressure suits to survive in the environment.
As I sign off, I give you the spacesuit from Alien screenplay writer Dan O’Bannon’s classic SF spoof Dark Star, complete with silver-painted muffin tray fastened to the front.