A rather lovely little number this, inspired by NASA’s orange space shuttle suits with helmets built upon and around this...
which is a SCOTT safety Helmet.
The story is set way in the future on Sanctuary Base 6, a space base on the surface of a planet which is somewhat impossibly orbiting a black hole. It’s a cracking two parter with plenty of suspense and spooks to go round and well worth checking out if you haven’t had the pleasure yet.
A revamp of this suit appears the following year in the episode; 42 and the actual suit seen here and borrowed by The Doctor in these episodes turns up again a whole three years later when the Timelord goes a visiting Mars intent on a little stroll.
It's all been blogged so go check it out.