There were just 6 spacesuit costumes used in the series, plus the two silver spacesuits/ fire suits.
The outer fabric is orange cotton, ribbed by stitching (there is close ribbing around upper torso to shoulders, middle of arms, and upper legs, simulating the "tomato worm" design of real suits).
Zips are white. The main zips are on the front and on the insides of arms and legs. There are pockets, with zips, on the outside forearm of the right arm (occasionally the left; not on Victor's/Helena's), on the front of upper legs (Koenig's pockets are in a higher position) and on the outside of the left leg below the knee. Most of the zip pockets are not functional.
The legs have a "metal" (fibreglass) ring on the end, and the arms have a bearing (fibreglass ring) with controls which attaches to the gloves.
A chest pack (DCM) and a back pack (PLSS) are worn in space, secured with belts. Individuals are identified by their name on the helmet above the visor, and a number on the chest and back packs. Apparently each Alphan has their own spacesuit (they do not swap the name labels on their helmets). In Year One living quarters, we often see spacesuits and helmets in the cupboards; in The Last Enemy, Sandra clearly has two spacesuits in her quarters.
EVA packs are seen in Space Brain & The Exiles (no back packs are necessary). The packs in The Exiles do not have the central black cylinder seen in Space Brain. One of the firemen in The Bringers Of Wonder part 1 also does not have a backpack. Presumably there is an oxygen supply in the chest pack/DCM.
Because there were only 6 different spacesuits, in some sequences (such as Space Brain) the cast had to exchange suits between shots so they could all appear to be wearing spacesuits.
Suit number 4, seen here worn by Paul Morrow but also worn by Bergman and Maya, has a white zip on the left arm. All the other suits only have the zip on the right arm.
In Black Sun, a real pocket appears on Bergman's suit. The other zips do not have pockets behind them. Similar "practical" pockets were added to Helena's suit (visible in The Infernal Machine) and Bartlett's suit (visible in Bringers of Wonder)
Under the spacesuit, astronauts often wear black balaclavas under the helmets, although these are rarely obvious on screen. They are probably car racing or motor-cycle balaclavas, which are fire-retardant and not dissimilar to the "snoopy caps" which included headphones and microphones, worn by real astronauts under their helmets.
Changes in Year 2 included a new badge indicating the Eagle number on both arms, buckles on the belts and revisions to the chest and back packs. The Eagle number is always present, even if the astronaut never boarded an Eagle (Space Warp). Sometimes the Eagle number is incorrect; in The A B Chrysalis Koenig's suit says "Eagle 4" while Alan's is (correctly) "Eagle 1".
Zienia Merton's spacesuit, with belt and gloves but without the original packs and helmet, sold for $8000 in August 2013. See the costume guide for further details.
Copyright Martin Willey