Today we got a tour of the NASTAR center which has some impressive aircraft simulators and a gigantic centrifuge (11 ton, 25-foot arm, with bolts going 45 feet down into the bedrock and a huge mass of concrete underneath to keep it stable as it swings around). Then we had a course on the physiology of hypoxia (oxygen deprivation) and some basics on atmospheric physics before getting fitted with oxygen masks and heading for the altitude chamber. I’m not actually sure that’s the write term, but it’s a room with a dozen seats and ports for oxygen masks and can have its pressure adjusted to simulate various altitudes.
After 30 minutes of denitrogenation (breathing pure oxygen to remove nitrogen bubbles from the blood to reduce the likelihood of those bubbles expanding to painful size on ascent to high altitudes), we took our masks off and they took the chamber up to 18,000 feet. That is to say, they lowered the pressure in the room to what it is at an altitude of 18,000 feet. At that altitude, the pressure is about half what it is at sea level. So each breath delivers half the oxygen of a breath at sea level. We had some simple exercises to perform – simple math operations, some writing – to identify any degradation in mental function as we entered a hypoxic state. I noticed an increased heart rate, but no other symptoms. I have done two altitude “flights” in the past, about 10 years ago, with no noticeable effects. I could not tell if the increased heart rate was due to lack of oxygen or simple anxiety about possibly worse effects. After about 15 minutes, one member of our group passed out. By that time I was feeling a bit tired, but otherwise no overt effects of hypoxia. My simple math problems were done without error, as were the two mazes.