Personally, I wonder if it's even necessary to build up to the spacewalk, given its relative importance in the grand scheme of things. In a sense it seems like the ritual that puts the Magvel twins in the astronauts' club; I wonder if it would work to start off with the spacewalk or the launch of the spacewalk.

Of course I'm not privy to the whole plot nor your intentions regarding your setup (the innocence of the Magvel twins before they become Real Astronauts, perhaps?) so this is all my humble outside opinion.