Physiological Effects during Aerobatic Flights on Science Astronaut Candidates
Spaceflight is considered the last frontier in terms of science, technology, and engineering. But it is also the next frontier in terms of human physiology and performance. After more than 200,000 years humans have evolved under earth’s gravity and atmospheric conditions, spaceflight poses environmental stresses for which human physiology is not adapted. Hypoxia, accelerations, and radiation are among such stressors, our research involves suborbital flights aiming to develop effective countermeasures in order to assure sustainable human space presence. The physiologic baseline of spaceflight participants is subject to great variability driven by age, gender, fitness, and metabolic reserve. The objective of the present study is to characterize different physiologic variables in a population of STEM practitioners during an aerobatic flight. Cardiovascular and pulmonary responses were determined in Science Astronaut Candidates (SACs) during unusual attitude aerobatic flight indoctrination. Physiologic data recordings from 20 subjects participating in high-G flight training were analyzed. These recordings were registered by wearable sensor-vest that monitored electrocardiographic tracings (ECGs), signs of dysrhythmias or other electric disturbances during all the flight. The same cardiovascular parameters were also collected approximately 10 min pre-flight, during each high-G/unusual attitude maneuver and 10 min after the flights. The ratio (pre-flight/in-flight/post-flight) of the cardiovascular responses was calculated for comparison of inter-individual differences. The resulting tracings depicting the cardiovascular responses of the subjects were compared against the G-loads (Gs) during the aerobatic flights to analyze cardiovascular variability aspects and fluid/pressure shifts due to the high Gs. In-flight ECG revealed cardiac variability patterns associated with rapid Gs onset in terms of reduced heart rate (HR) and some scattered dysrhythmic patterns (15% premature ventricular contractions-type) that were considered as triggered physiological responses to high-G/unusual attitude training and some were considered as instrument artifact. Variation events were observed in subjects during the +Gz and –Gz maneuvers and these may be due to preload and afterload, sudden shift. Our data reveal that aerobatic flight influenced the breathing rate of the subject, due in part by the various levels of energy expenditure due to the increased use of muscle work during these aerobatic maneuvers. Noteworthy was the high heterogeneity in the different physiological responses among a relatively small group of SACs exposed to similar aerobatic flights with similar Gs exposures. The cardiovascular responses clearly demonstrated that SACs were subjected to significant flight stress. Routine ECG monitoring during high-G/unusual attitude flight training is recommended to capture pathology underlying dangerous dysrhythmias in suborbital flight safety. More research is currently being conducted to further facilitate the development of robust medical screening, medical risk assessment approaches, and suborbital flight training in the context of the evolving commercial human suborbital spaceflight industry. A more mature and integrative medical assessment method is required to understand the physiology state and response variability among highly diverse populations of prospective suborbital flight participants.
 Accident Brief. NTSB/AAB-12/01. PB2012-102899. Pilot/Race 177, “The Galloping Ghost,” North American P-51D, N7911.
 Aerospace Medical Association Task Force on Space Travel, “Medical guidelines for space passengers,” Aviat Space Environ Med, 2001; 72(10):948-50.
 Blue Origin (2018) New Shepard Payload User’s Guide for Research and Education Missions. NSPM-MA0002-E Rev E. Available via request at https://www.blueorigin.com/
 R. S. Blue, J. M. Pattarini, D. P. Reyes, R. A. Mulcahy, A. Garbino, C. H. Mathers, J. L. Vardiman, T. L. Castleberry, and J. M. Vanderploeg, “Tolerance of centrifuge-simulated suborbital spaceflight by medical condition,” Aviat Space Environ Med, 2014 Jul; 85(7), 721-729.
 R. S. Blue, J. M. Riccitello, J. Tizard, R. Hamilton, and J. M. Vanderploeg, “Commercial Spaceflight Participant G-Force Tolerance During Centrifuge-Simulated Suborbital Flight,” Aviation Space and Environmental Medicine, 2012, 83(10):929-34, DOI: 10.3357/ASEM.3351.2012.
 Center of Excellence for Commercial Space Transportation, “Flight Crew Medical Standards and Spaceflight Participant Medical Acceptance Guidelines for Commercial Space Flight,” June 30, 2012.
 Federal Aviation Administration, U.S. Department of Transportation, Advisory Circular, “A Hazard in Aerobatics: Effects of G-forces on Pilots,” 1984.
 Federal Aviation Administration, U.S. Department of Transportation, “Guidance for Medical Screening of Commercial Aerospace Passengers,” 2003.
 Federal Aviation Administration, Office of Commercial Space Transportation, “Recommended Practices for Human Space Flight Occupant Safety,” 2004.
 S. I. Fox, “Laboratory Guide to Human Physiology,” 9th ed, McGraw-Hill, 2004. ISBN 0-07-319224-4.
 C. Y. Guézennec, F. Louisy, H. Portier, D. Laude, B. Chapuis, and J. Plésant. “Effects of aerobatics flight on oxygen consumption and heart rate control: influence on autonomic cardiovascular regulation during recovery,” Eur J Appl Physiol, 2001 Jun;84(6):562-8.
 P. D. Hodkinson, R. A. Anderton, B. N. Posselt, and K. J. Fong, “An overview of space medicine,” British Journal of Anesthesia, 2017, 119(S1): i143-i153.
 A. S. Jackson, M. L. Pollock, “Practical Assessment of Body Composition,” Physician and Sportsmedicine, 1985 May; 13(5):76-90. doi: 10.1080/00913847.1985.11708790.
 E. Jackson, “An Investigation of the Effects of Sustained G-Forces on the human Body During Suborbital Spaceflight,” Master of Science in Aerospace Engineering. KTH Royal Institute of Technology, Stockholm, Sweden, 2017.
 W. R. Kirkham, S. M. Wicks, and D. L. Lowrey, “G Incapacitation in Aerobatic Pilots: A Flight Hazard,” FAA-AM-82-13.
 P. J. Llanos, and H. W. Hays, “Flight Operations Quality Assurance Analysis for Contingency Scenarios of SpaceShipTwo using ERAU's Suborbital Space Flight Simulator,” AIAA SPACE and Astronautics Forum and Expositions, AIAA SPACE Forum, (AIAA 2017-5111).
 P. J. Llanos, and E. L. Seedhouse, “Application of Bioinstrumentation in Developing a Pressure Suit for Suborbital Flight,” Computing in Cardiology, Vancouver, September 2016.
 P. Llanos, V. Kitmanyen, E. Seedhouse, R. Kobrick, “Suitability Testing for PoSSUM Scientist-Astronaut Candidates using the Suborbital Space Flight Simulator with an IVA Spacesuit,” 47th International Conference on Environmental Systems. ICES-2017-100 16-20 July 2017, Charleston, South Carolina.
 M. M. Metzler, “G-LOC Due to the Push-Pull Effect in a Fatal F-16 Mishap”, Aerosp Med Hum Perform, 2020 Jan 1;91(1):51-55. doi: 10.3357/AMHP.5461.2020.
 P. V. McDonald, J. M. Vaderploeg, K. Smart, and D. Hamilton, “AST Commercial Human Space Flight Participant Biomedical Data Collection,” Wyle Laboratories, Inc. Technical Report#LS-09-2006-001, February 1, 2007.
 V. J. Michaud, and T. J. Lyons, “The ‘Push-Pull Effect’ and g-induced loss of consciousness accidents in the U.S. Air Force,” Aviation Space and Environmental Medicine, 1998, 69(11):1104-6.
 D. G. Newman, “High G flight: physiological effects and countermeasures,” 2015, Ashgate Publishing. ISBN 10: 1472414578; ISBN 13: 9781472414571.
 R. B. Rayman, M. J. Antuñano, Garber M. A., J. D. Hastings, P. A. Illig, J. L. Jordan, R. F. Landry, R. R. McMeekin, S. E. Northrup, C. Ruehle, A. Saenger, and V. S. Schneider, “Space Passenger Task Force: Position Paper: Medical guidelines for space passengers-II,” Aviat Space Environ Med, 2002; 73(11):1132-4.
 S. Tommaso, “Guidelines for the safe regulation, design and operation of Suborbital Vehicles,” International Association for the Advancement of Space Safety, May 2014.
 E. K. Zawadzka-Bartczak, and L. H. Kopka, “Cardiac arrhythmias during aerobatic flight and its simulation on a centrifuge”, 2011, Aviat Space Environ Med, 2011, Jun;82(6):599-603.