Some of my thoughts rereading this chapter and looking at everything in more detail.
Primordial Fear = The Dark
Space? The Infinite Dark.
The astronauts are a symbol of mankind and our worship/fear towards the concept of the unknown, adventurers of the final frontier. Though we made torches and lit up our cities, space is still the last dark jungle to explore. It's a such a vast nothingness that you can't help but fear what it has, or what it doesn't have. The astronauts have been bifurcated and separated from their legs, separated from the connection of certainty one constantly has while walking on solid ground. Now they are praying that they can reconnect with them, and be assured of their sense of place, that they aren't floating in the abyss.
The Darkness Devil took everyone's arms on the same principle. When blinded, everybody will fumble around to grab hold of anything to give themself a sense of place, but thats pretty hard to do when you don't have arms in the first place.