An Investigation of the Effects of Sustained G-Forces on the Human
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An Investigation of the Effects of Sustained G-Forces on the Human Body During Suborbital Spaceflight In Fulfilment of the Degree: Master of Science in Aerospace Engineering Eric Jackson KTH Royal Institute of Technology Stockholm, Sweden June 30, 2017 SAMMANFATTNING (SWEDISH) Inom en snar framtid ¨ardet troligt att privata, kommersiella rymdflygningar ¨arm¨ojliga,d¨arpassagerarna inte kommer att vara utbildade astronauter och, till majoriteten, troligtvis ¨aldre.Dessa personer kommer att uts¨attasf¨or h¨ogaG-krafter vilket utan avancerad tr¨aningmedf¨orrisker som inte beaktats i detalj tidigare. Accelerationsprofilerna f¨orde tv˚arymdfarkoster som just nu utvecklas kommersiellt var analyserade utifr˚anofficiellt tillg¨anglig data. Videoanalys utf¨ordesutifr˚anfilmer av testflygningar och m¨anskligacentrifugtester anv¨andes f¨oratt f˚afram individuell data. Dessa var sedan kombinerade f¨oratt f˚afram accelerationsprofiler f¨orb˚adafarkosterna. Baserat p˚adessa profiler och de maximala G-krafterna som uppn˚addesanalyserades de m¨ojligariskerna f¨or passagerarna utifr˚anett medicinsk perspektiv. 1 ABSTRACT With the advent of private commercial suborbital spaceflight, a new demo- graphic of untrained individuals will begin to travel to space. These individu- als are exposed to high levels of G-forces, resulting in medical considerations which are not a normal factor with high performance fighter pilots or astro- nauts. The acceleration profiles of the Virgin Galactic and Blue Origin spacecraft were obtained from publicly available data. Video analysis was performed on footage of spacecraft test launches and human centrifuge tests to obtain individual data sets. These data sets were used to develop the acceleration profiles for both spacecraft. Based on the spacecraft's acceleration profiles and peak G-forces, medical conditions were investigated and considered to identify potential risks that may affect the passengers, particularly the elderly. 2 3 ACKNOWLEDGEMENTS I would like to thank my advisors Christer Fuglesang and Ola Eiken from KTH Royal Institute of Technology for their constant feedback and expertise throughout my thesis. A special thank you as well to Desir´eeBrundin who was kind enough to take the time to translate my abstract into Swedish and to oppose my thesis defence. 4 NOMENCLATURE Notations Symbol Description a Acceleration dm Change in mass m g Force of gravity on earth [9:81 s2 ] G A multiple of gravity experienced due to acceleration I Inertia r Radius T Torque 5 Abbreviations AGARD Advisory Group for Aerospace Research and Development AGSM Anti-G Straining Manoeuvre A − LOC Almost Loss Of Conciousness bpm Beats Per Minute CAD Coronary Artery Disease COP D Chronic Obstructive Pulmonary Disease CSM Command/Service Module CVD Cardiovascular Disease G − LOC G-force induced Loss Of Conciousness HIVD Herniated Intervertebral Disc ISS International Space Station km Kilometer kph Kilometers Per Hour LM Lunar Module mmHg Millimeter of Mercury WHO World Health Organization 6 Contents SAMMANFATTNING (SWEDISH) 1 ABSTRACT 2 ACKNOWLEDGEMENTS 4 NOMENCLATURE 5 Notations . .5 Abbreviations . .6 TABLE OF CONTENTS 7 1 INTRODUCTION 10 1.1 Background . 11 1.2 Scope and Objectives . 11 1.3 Method . 12 2 G-FORCE BACKGROUND 13 2.1 Orientation . 14 2.2 Human Limits . 16 2.3 Training . 18 2.3.1 Human Centrifuge . 18 2.3.2 0-G Flight . 21 2.4 Fighter Pilots . 25 2.4.1 Anti-G Suits . 25 7 2.4.2 Anti-G Straining Manoeuvre . 26 2.5 Spacecraft G-Profiles . 27 2.5.1 Soyuz (USSR/Russia) . 27 2.5.2 Space Shuttle (USA) . 28 2.5.3 Apollo (USA) . 29 2.5.4 Mercury (USA) . 31 3 MEDICAL BACKGROUND 32 3.1 Cardiovascular System . 32 3.1.1 Clots . 33 3.1.2 Coronary Artery Disease . 33 3.2 Thoracic Cavity . 34 3.2.1 Heart . 34 3.2.2 Lungs . 35 3.3 Intracranial . 36 3.3.1 Ischemic Stroke . 37 3.3.2 Hemorrhagic Stroke . 37 3.3.3 Cerebral Hypoxia . 37 3.4 Skeletal . 38 3.4.1 Osteoporosis . 38 3.4.2 Spinal . 39 3.4.3 Ribs . 40 3.5 Ophthalmology . 41 3.5.1 Tunnel Vision . 41 3.5.2 Blackout . 42 3.5.3 A-LOC . 42 3.5.4 G-LOC . 42 3.6 Dermatology . 43 3.7 Cancer . 43 3.8 Medical Drugs . 44 3.9 Pregnancy . 44 3.10 Supplements . 45 8 3.11 Physiological Differences Between Men and Women . 46 3.12 Age . 46 4 METHOD 47 4.1 Spacecraft Specifications . 47 4.1.1 Blue Origin . 47 4.1.2 Virgin Galactic . 49 4.2 Video Analysis . 50 4.2.1 Blue Origin . 51 4.2.2 Virgin Galactic . 53 5 RESULTS 56 5.1 Blue Origin . 56 5.2 Virgin Galactic . 57 6 DISCUSSION 60 7 CONCLUSIONS 63 8 FUTURE WORK 65 REFERENCES 67 9 Chapter 1 INTRODUCTION In recent years, well funded private space exploration companies have made great strides towards successful commercially viable spacecraft opening the door to the possibility of commercial space tourism. This indicates a shift in the average demographic of those travelling to space away from the highly trained astronaut towards an average, untrained and largely unprepared In- dividual. Furthermore, the high cost off the flights, currently in the hundreds of thousands, will potentially shift the client age demographic towards more senior citizens. This is in general a result of the elderly likely enjoying a higher salary, or being already retired with comfortable liquid assets as op- posed to younger generations who may spend their money elsewhere such as on student loans or mortgages. Consequently, medical considerations need to be re-evaluated to meet the new demographic travelling to space, and conditions which may not generally affect professional astronauts must now be considered. After defining the thesis in Chapter 1, background information on G-forces and an overview of medical considerations will be discussed in Chapters 2 and 3 to highlight relevant material. The background overview will be followed by Chapter 4 which covers how the G-force profiles will be determined and Chapter 5 which presents the results. Finally, the results will be discussed in Chapter 6 and conclusions on the risks associated with suborbital spaceflight will be considered based on the G-force profiles found. 10 1.1 Background With the advent of performance aircraft in the early 20th century, the effects of G-forces on the human body quickly came to light and research began to identify the causes, limits and training methods to minimize risk and maximize G-force tolerance. While the knowledge base has been greatly improved over the years, research has been limited in general to specialized professionals such as astronauts and military pilots. Large scale research on the effects of G-forces has been further limited to males due to the lopsided gender imbalance in these professions. This disparity has resulted in a large gap in the data on how G-forces affect different demographics with respect to physical and medical considerations. 1.2 Scope and Objectives Before the risks can be assessed, the amount of G-forces experienced, along with the onset rate and duration must be determined for the commercial space vehicles. Given that the acceleration profiles of the remaining two commercial suborbital space tourism companies Virgin Galactic and Blue Origin are not public knowledge, video analysis will be performed on footage from test launches to develop acceleration profiles from which decisions can be made. The current body of research on the effects of G-forces on the human body is largely the result of tests on highly trained subjects who have been cleared for flight at a high medical standard. The advent of space tourism however, is introducing average people who are well outside the scope of research that has been performed on professionals, and so come with a host of new considera- tions with respect to the G-forces experienced. Upon obtaining the accelera- tion profiles of the two spacecraft, the duration and onset rate of the largest G-forces can be determined and the standard risks from sustained G-force exposure can be investigated to determine how well the current guidelines hold up with the deteriorating health of elderly passengers. Furthermore, new conditions that are prevalent in the elderly, but non-existent in current high G-force exposure groups will need to be considered and investigated to determine if and when they become a risk and what limitations should be imposed as a result. 11 1.3 Method To determine the acceleration profiles of the suborbital spacecraft, video analysis will be performed. For certain spacecraft, there is the possibility of performing the analysis several different ways in order to increase the level of confidence that the G-force profile has been properly determined. To begin, some test flight videos display output such as the speed the spacecraft is travelling. This data can be extracted frame by frame to develop a dataset which can be used to calculate the acceleration and G-forces experienced by spacecraft. Should data output from videos not be available, it may also be possible to determine the speed and acceleration of the spacecraft by measuring its movement against a background, such as mountains or the ground. This op- tion is more limited as some footage is shot against a featureless background, however this may provide a decent way to check if data output is correct and to identify any masking that may have been applied to the data feed to keep some of the spacecraft specifications secret. 12 Chapter 2 G-FORCE BACKGROUND When considering G-forces there are in general two types to look at: Sus- tained and transient. Transient G-forces are generally associated with an impact such as a crash, and take place over a very short period of time.