In the past two days Butch and I did many hours of maintenance on an EMU suit and this was without a doubt the most difficult and delicate activity that I have performed on orbit so far.
The EMU is the NASA pressure suit for spacewalks – basically, it’s a little spaceship for one person that can keep you alive outside of the Space Station for several hours, providing oxygen for breathing and pressurization, cooling water, scrubbing of CO2, communication and probably a few more things I am forgetting.
One of the most important components of the life support system is the Fan-Pump-Separator, FPS for friends. It’s one single, surprisingly small unit containing the fan that provides ventilation, the pump that circulates cooling water and the separator that removes condensate water (from sweat and breathing) out of the ventilation loop, to keep humidity under control in the suit and prevent fogging of the helmet.
The FPS has failed on the suit that is intended to be used by Terry in January and we flew a replacement part with us on the Soyuz, which Butch and I got to install. What makes this work so difficult is that is wasn’t originally intended to be performed on orbit, so the design is not weightlessness-friendly.
For example, the screws are non-captive: not a trivial detail when you’re trying to remove and then install tiny screws with multiple washers in difficult-to-access places.
So, how do you approach a task like this? Well, for one thing, with a lot of eyes: not only ours, but also of a team of specialists on the ground following along on multiple camera views. Then you have a person on the ground serving as CAPCOM for this particular activity, who is extremely familiar with all the aspects of the procedure: how nice that this person was Mark Vande Hei, from our NASA sister class of 2009. Always nice to talk to Mark!
Then you have a very well-honed procedure and a number of videos detailing every step, in addition to special measures such as putting a mesh on the head of a vacuum cleaner and have it placed appropriately to catch any part that you might lose hold of. And then you need to take it very slow and be extremely meticulous about every action and about tracking parts and tools. Butch and I joked that we were performing surgery on the suit.
So, the new FPS is in place and Butch is scheduled for the checkout tomorrow – hopefully that will confirm that we have a functioning suit for Terry to use in January. Which reminds me that the astronaut profession really requires an extra measure of faith and trust in your fellow human beings. For example, in your crewmates, who replaced a component your life will eventually depend on!
Of course, it’s not only trust, we do have a checkout planned: in fact Butch will perform it tomorrow. So it’s still early to cheer, but if everything goes well it will be very rewarding to look back at this challenging work!
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