My fellow Shenanigan Alex and I had the pleasure of meeting one of our Orlan instructors again. It’s incredible, but it’s been almost almost a year and a half since he taught us about the Russian spacewalks suit!
This time it wasn’t about preparing us to do an Orlan spacewalk (EVA), but rather to teach us how to be the so-called “third operator”, the person assisting the spacewalking crewmembers with pre-EVA and post-EVA procedures.
You may wonder why we would be fulfilling that role, since there is always a third Russian crewmember on-board and he/she is bound to have a lot more training in the Russian procedures. Well, the thing is that this person would most likely be isolated in his/her Soyuz.
If you take a look at the picture I’ve attached, it will all make sense.
In the yellow circle I’ve indicated the module which is used as airlock, meaning the module that is isolated from the rest of the Space Station and depressurized, before spacewalkers open the hatch and exit. When spacewalkers come back inside and close the hatch again, before connecting the airlock again to the rest of the Station we verify that there is no leak to the outside. Imagine, for example, that we damaged the hatch and could not close it properly any more: if we reconnected the airlock to the rest of the ISS, we would depressurize the entire Station!
So, Russian EVA procedures foresee a solution for this contingency: the two spacewalkers would get into the small module that I have highlighted in red, called Transfer Section (переходный отсек) and basically use that as a contingency airlock.
To protect for this possibility, all four hatches of the Transfer Section are closed and leak checks are performed before the EVA – one of the tasks of the third operator, by the way.
Now, of the six ISS crewmembers, three have their Soyuz docked to MRM2 and three to MRM1 (this latter will likely be the case for Alex and myself).
As you can easily see, the Soyuz that is docked to MRM2 remains isolated from the rest of Station. So, crewmemers of that Soyuz who are not outside doing the spacewalk need to wait in the MRM2/Soyuz volume, because they can not remain separated from their spaceship. And because of the way crews are composed and docking ports are utilized, most likely the third Russian crewmember would be one of those isolated in there.
Hence the need to ask a non-Russian to serve as third operator. Alex and I are an obvious choice, since we’ve already been certified in performing Orlan spacewalks and we only needed a quick refresher.
By the way, you can see some pictures of our Orlan training a while back here:
https://www.flickr.com/photos/astrosamantha/sets/72157631685452043/
29/01/2014