Vomit Comet Blog: Friday, May 5, 2006
posted by Vinaya
Valsalva. The word of the day is valsalva. According to the Merriam-Webster dictionary, it means, “the process of making a forceful attempt at expiration while holding the nostrils closed and keeping the mouth shut for the purpose of testing the patency of the eustachian tubes or of adjusting middle ear pressure.” According to NASA, it's a fancy word for clearing the pressure in your ears and sinuses while on a plane. (You've probably done this yourself during a particularly bad airplane flight, to relieve the pressure building up in your ears.) More on valsalva later. Here we go...
Today we went though physiological training at NASA’s Sonny Carter Training Facility, and the location of the Neutral Buoyancy Laboratory (NBL). This is the same place where NASA trains its astronauts for space training. The pool--which is 202' long by 101' wide by 40' deep--contains a mockup of one of the modules of the International Space Station and a replica of the cargo bay of the Space Shuttle. This pool is huge. More about that later, though...
We underwent physiological training today using an altitude chamber, also called a hypobaric chamber or at NBL...simply "The Chamber." Before we could get in though, we spent the morning in a classroom learning about the effects of high altitude on the body.
In the first hour, we learned about the atmosphere, and the effects of breathing and circulation that come from high altitude. The physiological effects on the body from the atmosphere at sea level to 10,000 feet--called the physiological efficient zone--are few. Supplemental oxygen is not required to breathe and the body adapts pretty easily to minor changes. From 10,000 feet to 50,000 feet--the physiological deficient zone--requires a pressurized cabin or oxygen equipment to breathe. The lack of atmosphere pressure at this altitude causes major physiological problems--mainly hypoxia and hyperventilation. The space equivalent zone--anything above 50,000 feet--requires a full pressure suit or a sealed cabin to breathe.
A mock up of the ISS underwater.
Hypoxia and hyperventilation were discussed next. The symptoms and signs of hypoxia, which is a state of oxygen deficiency in the blood, tissues and cells sufficient to cause an impairment of mental and body functions. Symptoms and sign fall into two categories. Objective symptoms, which can be noticed by an observer, and subjective symptoms, which an individual feels by him/herself. Objective symptoms include increased rate of breathing, cyanoisis (turning blue), slurring of speech, poor coordination, mental confusion, euphoria, belligerence and lethargy. Subjective symptoms, which don't always affect people in the same way, include blurred vision, tunnel vision, air hunger, apprehension, fatigue, headache, belligerence, hot and cold flashes, euphoria, dizziness numbness, tingling in the fingers, and nausea. We learned what to do in hypoxia situations and how to recognize them in ourselves and others. Hyperventilation, which is an abnormal increase in the rate and depth of breathing, should be avoided in panic situations.
Next we learned about the valsalva. Even though I've been using this technique for years on long airplane flights, I didn't' know it had a name. Or that it was even a recognized form of pressure control. I did learn that I've been exhaling too hard, and that could be a problem. Simply hold your nose, and keeping your mouth shut, exhale SLOWLY until the pressure in the ears is relieved. During increased pressure situuations, the trapped gas in your body expands, causing the buildup of pressure.
SCUBA divers will be familiar with a phenomenon known as decompression sickness, a disorder produced by the evolution of nitrogen gas from tissues and fluids of the body. Similar things happen to those with too much nitrogen in their blood following HIGH altitude situations.
Me with my oxygen mask
Lastly, we learned about spatial disorientation, the inability to accurately orient oneself with the respect to the earth's horizon. This is a huge problem for pilots. Which is why they have to trust their instruments and not their senses. Hard to do, but it could be lifesaving. This discussion also included the signs and symptoms of motion sickness and how to deal with them onboard our zero G flight. No quick movements of the head, and a good night's sleep were easy ways to (hopefully) avoid motion sickness on our flight.
After a short lunch break, we were all issued our own oxygen masks. It was like something out of the movie Top Gun, or something. Kinda cool, but restricting as well. After learning about the equipment, how to use it and what to do in case of malfunction, we were ready for our "flight" in the hypobaric chamber. They call it a flight, because The Chamber simulates the change in air pressure from sea level to 25,000 feet (on our flight, but they can simulate it higher than that). The Chamber doesn't move, it's mostly concrete.
The class was split into two groups. I was the first group. The Chamber, about 15 feet long and 6 feet wide, contains two facing rows of eight chairs. Each seat is equiped with two oxygen regulators. Before our flight, we had to breathe 100% pure oxygen for 30 mins. in order to remove the excess nitrogen in our systems to remove the possibility of decompression sickness. During the 30 mins, we were able to try out breathing from the regulators as if we were pilots at 30,000 feet, 40,000 feet and 45,000 feet. The last one--45K--was the hardest. The oxygen is pushing into the mask so hard, that it's difficult to breathe out.
Inside The Chamber
Finally, we began our flight. You could feel the pressure building throughout the body. We were encouraged to release the build up of gas from our body...either through belching or the other way. (Social rules are suspended in The Chamber.) Everyone was wearing an oxygen mask, anyway, so no one would know. The Chamber is designed with facing seats, so that one side of passengers can observe the other. The first set of participants in The Chamber were asked to remove their masks. (There is air in the cabin, so no one is gasping for breath, it's just that the pressure is higher.) You can almost immediately see the affects of hypoxia on the body. Disorientation, light-headedness. Each person is then asked to document the affects of their body using a worksheet. After five minutes, everyone put their oxygen masks back on.
The pool at NBL
Then is was my turn. Without my mask on, I immediately felt light-headed and in a fog. It's a very similar feeling to being drunk (I've heard...haha). My worksheet didn't get filled out very well. They asked each person to spell their last name's backwards. I told them that was just cruel, with my last name. [Ed.'s Note: Vinaya's last name is Sathyasheelappa.] Five minutes without the mask before we could put them back on. (Although, if anyone is feeling really bad, they can put their mask on at anytime.) An emergency blast from the oxygen mask and we were almost back to normal very quickly. They brought us back down to sea level and our flight in The Chamber was over.
After a short debriefing, we each received a certificate and a physiological training card good for three years. So I don't have to do that again for three years. We were all done with physio-training.
While the second group "flew" in The Chamber, we took a quick tour of the NBL. As I said earlier, this pool is HUGE. The pictures don't really do it justice. But go to the website to see some underwater pics. Yes, it really is that blue!. Obviously, I couldn't go in the pool, which contains 6.2 million gallons of water, but we were able to look in the test control room. Earlier in the day, two astronauts (the next two to go on the ISS!), were doing some training in the pool. They train for six hours at a time. That's a long time to be underwater!
Well, after a long day, I'm starving. Breathing on oxygen is a LOT of work, and it's made me hungry. On Monday, the teams load their experiments on the plane and we get our first chance to get on the C-9. I can't wait.
Time until my flight: T-minus 4 days, 15 hours, 12 minutes...and counting.
Test Mission Control
Me at Test Control