Posey's Moonshot

Your Top Space Training Questions Answered: Introducing Posey's Moonshot

Welcome to a new series dedicated to Brien's spaceflight endeavors. For his inaugural post, Brien answers some of your most common questions, from what exactly he's training for to what's the deal with that human-sized centrifuge.

• By Brien Posey
• 01/31/2020

Welcome to Posey's Moonshot, my new column series dedicated to my spaceflight training. Although I am probably best-known for my IT-related writing (see my Posey's Tips & Tricks column here), IT isn't my only line of work. Since 2015, I have been actively training to fly on a commercial space mission.

Every once in a while, my IT career and my spaceflight training overlap with one another, as was the case when I used a Microsoft HoloLens in zero gravity. More often though, the two are completely separate.

Since my Tips & Tricks column focuses squarely on IT-related issues, I thought it might be fun to create another column dedicated to my spaceflight endeavors. My plan is to use Posey's Moonshot to talk about my experiences in training to go to space and to answer some of the questions that I am asked most often (as well as any reader questions that may come up).

What Exactly Are You Training For?
In the interest of full disclosure, let me say upfront that I am not a NASA employee, nor am I a NASA astronaut. I am training as a commercial scientist-astronaut candidate in preparation for a mission to study polar mesospheric clouds from space.

In case you are wondering, the title "scientist-astronaut" essentially means mission specialist. There are scientist-astronauts and pilot-astronauts. Even though I do have some piloting experience related to spaceflight, my role in the polar mesospheric cloud mission will be that of a scientist, not a pilot.

Another question that I get asked quite often regarding the title of "scientist-astronaut candidate" is what the word "candidate" means in this context. Basically, it means trainee. The program's rules stipulate that I don't get to drop the word "candidate" from my title until after I have flown in space. That day is definitely coming, but I haven't been to space yet.

What Does Your Family Think?
Over the last five years, there have been many other questions that I am asked over and over. I think that the one question that I get asked most often is, "What does your wife think about what you do?"

The short answer is that she has been unbelievably supportive, although initially I don't think that she quite understood the scope of what I was doing. Based on some of the things she said early on, I think maybe she thought that I was enrolling in some kind of space camp for adults.

What's Up with the Centrifuge?
Another question that I have been asked countless times is why astronaut training involves spending time in the centrifuge. In some ways, this question doesn't surprise me at all. Virtually every movie ever made about the space program includes a scene with someone going for a ride in the centrifuge.

In case you are not familiar with the centrifuge, it is a device that subjects you to the same gravitational conditions that you experience during launch and re-entry. I have experienced just over 6 Gs in the centrifuge (and 7 Gs in an airplane).

How Is This Different from Riding a Roller Coaster?
The centrifuge is probably the one aspect of astronaut training that people are most familiar with, so it seems only natural that I would get a lot of centrifuge-related questions. However, it was a follow-up question that really surprised me the first couple of times: Why, if there are roller coasters that can pull 5 Gs but don't require riders to have any special training, do astronauts need G-force training?

There are major differences between riding a roller coaster and riding a rocket. Some of these differences include the G-force onset rate, the G-force direction and, most importantly, the duration of the G-load. While there are roller coasters that can pull 5 Gs, riders normally experience a peak G-load for about a second. During a space launch, you may endure a sustained G-load for several minutes.

The next time you are in an amusement park, take a look at the shape of the loops on the park's roller coasters. You will notice that the loops are elongated rather than perfectly round. This is done to keep riders from having to endure sustained G-loads.

What Are the Different G-Forces?
G-forces can come at you in three different directions. G-forces coming through the chest are known as X Gs. You experience negative X Gs whenever you slam on the brakes in a car and are thrown forward. G-forces going from your head to your feet are known as Z Gs (more on those in a moment). There are also Y Gs, which is what you feel in a car when you go around a curve at a high rate of speed. Centrifuge training focuses on learning how to cope with X and Z Gs.

The X Gs are unpleasant (and can actually be painful) but comparatively speaking, they aren't all that dangerous. The sensation reminds me of having a broken rib. I have heard other people compare it to being in labor or having a Buick parked on their chest.

When you experience 6 Gs in the X orientation, it becomes difficult to breathe. Thankfully, there is a pressure-breathing technique that you can use to make breathing a lot easier. The technique is a little bit difficult to explain in writing, but it is very similar to playing a musical wind instrument like a trumpet or a saxophone. Incidentally, the only time that I have ever experienced X Gs that came close to those experienced during a space launch was when I once rode in a Top Fuel dragster at a charity event.

The G-forces in the Z orientation are more difficult to cope with. These are the G-forces that can cause you to lose consciousness. The reason why this can happen is really simple. G-forces make everything feel heavier than it normally would. Six Gs, for example, makes everything seem six times heavier. To put this into prospective, I currently weigh 155 pounds. At 6 Gs, my effective body weight would be 930 pounds.

As your effective body weight increases under G-load, so does the weight of everything inside of your body -- including your blood. The heart has trouble dealing with blood that is so much heavier than normal, so blood tends to accumulate in the lower extremities. As this happens, the brain becomes starved of oxygenated blood.

Have You Ever Passed Out?
I have never passed out in the centrifuge before, but the instructors have taken me right to the edge of losing consciousness so that I could see what it is like. The first thing that I noticed was that I lost my ability to see color; the world around me became black and white. From there, I began getting tunnel vision. It literally looked as though I were peering through a tube. After that, the tunnel gets narrower and narrower until it completely closes in. At that point, you are blind and are about to lose consciousness.

The thing that I found to be scary is that this entire sequence of events can happen in fewer than 10 seconds. By the time you realize that you are about to pass out, you only have a couple of seconds to do something about it.

The countermeasure is known as the anti-G straining maneuver. I could probably write an entire post on the finer points of this technique, but it involves tightening your muscles and forcing the blood back into your head. The odd thing about this is that when you get the blood back into your brain, your vision instantly returns to normal. The entire recovery process probably only takes about a second.

So that's a really long way of saying that the reason why astronauts need centrifuge training when roller coaster riders do not is because even though roller coasters can subject their riders to some high G-loads, those G-loads do not last long enough to require countermeasures.