On October 14, 2012 Felix Baumgartner jumped out of a capsule suspended under a helium-filled balloon as part of the Red Bull Stratos project. He and other men had done such jumps several times before, but on the 14th he did it at 128,000 ft (39, 045 m), making it the highest freefall ever. On the way down Baumgartner reached a speed of approximately 834 mph (1,343 km/h), making him the first human to exceed the speed of sound in freefall. (Note: All records still to be verified by relevant organizations) A team of physicians, scientists, engineers worked together to both keep him alive and to use the jump as a test-bed for research in high altitude physiology. Much has been written about the jump in the popular press, but we at Medgadget were most interested in the medical technology involved. Via email, Medgadget Editor Dan Buckland talked to Alex Garbino MD PhD, a resident in Emergency Medicine and a member of the Center for Space Medicine, both at Baylor College of Medicine in Houston, TX. Dr Garbino is on the Stratos Medical team headed by Jonathan Clark MD, who also provided some comments. The interview below is lightly edited for grammar and clarity, and includes some questions submitted to us on Twitter (@Medgadget and @MedGadgetDan) and email by readers.
1) What physiologic data were you hoping to get from this test?
Our system measured tri-axial acceleration, heart rate, 2-lead EKG, respiratory rate and skin temperature.
2) What devices did you use to get the medical/scientific data? Was it off the shelf components or did you have to do a lot of modification? What didn’t exist when you started that you had to fabricate?
We used the Equivital EQ-01 from Hidalgo. It was completely off the shelf – we wanted to ensure we had safe, tested and proven hardware as it was directly on Felix’s skin, in a 100% oxygen environment, and we only had one opportunity to record the data.
3) What types of data were stored vs what was sent down to the ground real-time?
Everything was locally recorded on the device itself. Although transmitting information real time would have been interesting from the media aspect, it would mean Felix’s private medical data being publicly released without screening, which can be a sensitive issue. There was no real medical value to seeing the data real time, as we had cameras that showed us what Felix was doing at all times, and most importantly, we have voice communications with him. If he can talk to us, we know his respiratory, cardiac and neurological systems are intact. If something was going wrong, there is nothing we could do until he was on the ground.
4) Were you happy with the quality of data received, and what technical challenges did you anticipate to actually encounter with the data recording itself?
The quality of the data was great. We anticipated that noise from motion artifact and possibly radio frequency interference would be an issue. Motion artifact was present, despite filtering algorithms, but are part of recording electrical potentials from the skin, which is how an electrocardiogram (EKG) works. We did have some issues ensuring good contact between the electrodes and the skin, since he wore a belt [that contained the EKG leads] rather than sticky electrodes. Ensuring the belt was tight but comfortable for hours at a time, and would work well inside a suit in every position imaginable took a lot of testing. Radio frequency interference was a non-issue, and there was no interaction with capsule systems.
5) Any general lessons learned in regard to physiologic monitoring in this environment?
Any physiologic system needs to be rugged and as unencumbering as possible. Most systems we looked at were large and bulky. Many, including the one we used, had certain parameters that could not be measured practically, like oxygen saturation, while wearing a pressure suit.
6) When/where do you hope to publish the medical results?
We hope to publish the results as soon as we compile, verify and analyze all the data from not just the final jump but also the test jumps. We are aiming to have everything complete by early next year and are planning on submitting to aerospace journals like Aviation, Space and Environmental Medicine.
Questions from readers:
7) Did you have any motion sickness countermeasures planned for ascent or descent? What were they?
Felix trained extensively in the suit and is an experienced skydiver, so he has not experienced issues with motion sickness during the fall.
The capsule ride is extremely smooth – it’s virtually motionless inside it, so no motion sickness was expected. The spin in freefall can be disorienting and could result in motion sickness, but Felix did spin training and wasn’t motion sensitive.
8) Seemed like a long trip, did the suit/capsule have a solid or liquid waste system? What was the contingency for vomiting either during ascent or on the way down?
The suit was designed to be worn for many hours, and includes a pass-through for liquid waste. Solid waste was not an issue as he was in the suit for only a few hours. We used a standard low residue diet similar to astronaut meals before spaceflight.
If he were to vomit in the suit, he would try to vomit to the side/down as much as possible. Unfortunately, there is little to be done until he is below 20,000 ft and he could open his visor.
9) Were there radiation concerns? Did the capsule have any radiation shielding?
There were no significant radiation concerns, so the capsule did not need shielding. Although he was at extremely high altitude, he was still very much below Earth’s radiation belts, which are hundreds of kilometers up and provide us with significant protection from space radiation. Furthermore, his time at altitude was very brief, as he jumped as soon as he got to float altitude, minimizing any additional exposure he would receive from the altitude. However, the primary concern for space weather was the potential effects on the GPS satellites which we used for establishing the freefall record. We had a dedicated space weather forecast for the jump.
10) What pressure was the suit pressurized to? And what was the gas makeup?
The suit pressurizes to 3.5 psi, which is the equivalent pressure to about 10,000 meters, or 33,000 feet. However, he is breathing 100% oxygen, so his lungs see it as the equivalent of breathing 23% oxygen at sea level, which is a little bit more than what is in the atmosphere – 21%.
He breathes 100% oxygen not so much because he has an increased oxygen requirement, but instead to ensure that he is minimizing the amount of nitrogen in his body. If he were to undergo a depressurization, the nitrogen dissolved in his tissues would form bubbles in his blood stream, which much like the “bends”, of Decompression Sickness (DCS), that one hears about from SCUBA divers.
11) What protocol did you follow to prevent DCS? And was their any special modifications you used for this particular jump?
We had the leading expert in the altitude DCS field calculate the most effective protocol for Felix. He would start breathing 100% O2 from before launch for a minimum of 75 minutes, and was on 100% O2 until he opened his visor on the way down.
12) What made the space suit different than the one NASA uses now?
The suit Felix wore was a slightly modified David Clark S1034 suit, based on the U2/SR 71 suit, which was the suit used on the Shuttle for the 1st four shuttle test flights. The Stratos suit is very similar to the NASA Advance Crew Escape Suit, or ACES suit model S1035 (aka the orange, or “pumpkin suits”). The most significant difference it that it has a conformal helmet – that is, one that fits snugly to Felix’s head (as a motorbike or motorsports helmet), very much like those worn by pilots of the U2 high altitude airplane. NASA uses non-conformal helmets, which means the astronauts can turn their heads inside the helmet. The bailout bottles [emergency oxygen system that is part of the parachute harness] were very similar to the NASA ACES system, but we had 2 parachutes instead of the single one used by NASA.