The Human Body and Weightlessness: Operational Effects, Problems and Countermeasures

331 Pages·2017·15.245 MB·English

by  William Thornton, Frederick Bonato

William Thornton · Frederick Bonato
The Human
Body and
Weightlessness
Operational Eff ects, Problems and
Countermeasures
The Human Body and Weightlessness
William Thornton • Frederick Bonato
The Human Body
and Weightlessness
Operational Effects, Problems
and Countermeasures
William Thornton Frederick Bonato
University of Texas Medical Branch Saint Peter’s University
Galveston, Texas, USA Jersey City, New Jersey, USA
ISBN 978-3-319-32828-7 ISBN 978-3-319-32829-4 (eBook)
DOI 10.1007/978-3-319-32829-4
Library of Congress Control Number: 2017942723
© Springer International Publishing AG 2017
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This book is dedicated to Dr. Tom Moore
whose unstinting and too often unrecognized
work in the early Shuttle flights
produced a number of the results described
here.
Preface and Acknowledgements
The intent of this work is to provide a better understanding of one of the more chal-
lenging problems of current and future space operations—the reaction of the human
body to a fundamental feature of the environment beyond that of Earth: weightless-
ness. This book was initially intended to be a small, readily accessible source of
information and data on the major operational problems caused by adaptation to
weightlessness. It was to be as simple as possible and comprehensible to virtually
all those working in human space flight but who are not necessarily familiar with
some relevant details, especially of the human body.
On beginning the chapter on space motion sickness, it became obvious that pub-
lished studies and data were too diverse to be adequate for operational planning, the
ultimate goal of this writing. This changed the planned format from a collation of
existing studies and data to one that required the generation of applicable evidence-
based information on the causes and effects of changes produced by weightlessness
and a search for data on these changes. Validity and relevance were the criteria used
in the selection of evidence, whether dating from before space flight or just discov-
ered during the writing itself.
The resulting product is based on the concept that the human body can make
physiological changes or temporary adaptations, which are compatible with weight-
lessness and a healthy body. These “somatic” adaptations are usually incompatible
with normal function in 1 g and must be considered during and after return to Earth
until re-adaptation has occurred. With one known exception, this is not a pathologi-
cal process. Such a concept is in contrast to that of many investigators and physi-
cians who treat these changes as pathologies to be prevented if possible.
A rational basis for the approach taken here is found in the evolution of our
marine ancestors’ bodies into our present form and function by innumerable species
adaptations. In almost every case of somatic adaptation we took a biophysical
approach, which began with the simplest functional unit in the systems involved;
e.g., the hair cell’s relationship to space motion sickness. Only those features
directly relevant to the problem are considered. Basic science is included when
deemed appropriate to provide a common basis for understanding of these
adaptations.
vii
viii Preface and Acknowledgements
It is written with the hope that the concepts here will be challenged where necessary
and augmented and extended as additional experience allows. This is especially true
in the case of the incomplete data in this book. The book could not have been done
without the support of many people, a number of whom may have been inadvertently
missed in the following list of acknowledgements and appreciation. The book began
with the authorization and support of Michael Coats, then director of NASA
JSC. Other essential contributions by people and organizations in JSC include the
art and graphics skill of David Russell who painstakingly translated ideas, images,
and data into the colorful graphics, which speak for themselves. Janine Bolton and
Kim So of the Life Sciences library patiently supported our search for information
and provided hundreds of files and sources. Mary Wilkerson in the photo archives
continued her gracious tradition of skillful searches for and provision of photographic
files. Some of the most valuable insights were provided by astronauts current and
past and by Alan Moore and Mark Guilliam of Wyle.
This work would have been absolutely impossible without the varied and
unstinting support of Sid Jones (retired) whose 38 years’ experience in graphic and
editorial work as a support contractor at JSC will survive indefinitely in many JSC
publications.
Typing sometimes almost illegible scripts by Kathy Hernandez of a San Antonio
firm has been an essential element here. My innumerable revisions were a burden to
all involved.
Many basics in the work described here began with the support of General Jack
Ord and by Brooks Air Force Base machine shop and were continued by the late
Henry Whitmore and Whitmore enterprises. Bruce Del Mar and Del Mar Avionics
contributed unique prototype hardware.
Drs. Tom Moore and John Uri at JSC provided essential support in execution,
both on the ground and in-flight investigations and their documentation. Chapters
on Space Motion Sickness (SMS), aspects of fluid shifts and exercise, would not
have been possible without the observations and measurements of crews on STS-2
through STS-61B. Dr. Norm Thagard’s clinical observations and electrophysiological
recordings on STS-7 and STS-8’s crew support, especially that of Cdr. Dick Truly,
were crucial to the ultimate understanding of SMS. Story Musgrave’s compliance
measurements on later missions confirmed key portions of Chap. 4. Many other
insightful crew observations are too numerous to credit.
Writing of this book was dependent on the moral, typing, and sustenance support
of my wife Jennifer.
Fair Oaks Ranch, Texas, USA William E. Thornton
Contents
1 An Introduction to Weightlessness and Its
Effects on Humans ................................................................................. 1
1.1 I ntroduction ..................................................................................... 1
1.2 B ackground ..................................................................................... 1
1.3 Weight and Weightlessness ............................................................. 5
1.4 Weightlessness During Spaceflight ................................................. 8
1.5 Brief History of Major Effects of Weightlessness........................... 11
1.6 Space Motion Sickness ................................................................... 12
1.7 Fluid Shifts and Losses ................................................................... 13
1.8 M usculoskeletal Effects .................................................................. 14
1.9 C ardiopulmonary Effects ................................................................ 14
1.10 Metabolic Effects ............................................................................ 15
1.11 Neuromuscular Adaptation.............................................................. 15
1.12 Effects of Accommodation.............................................................. 16
1.13 Anthropometric Accommodations .................................................. 16
1.14 Postural Change .............................................................................. 16
1.15 Other Changes ................................................................................. 16
1.16 Summary of Effects ......................................................................... 17
Additional Background ............................................................................ 18
References ................................................................................................ 19
2 Basic Mechanisms .................................................................................. 21
2.1 Introduction ..................................................................................... 21
2.2 Species Adaptation .......................................................................... 23
2.3 Somatic Adaptation ......................................................................... 24
References ................................................................................................ 30
3 Space Motion Sickness and Vestibular Adaptation
to Weightlessness .................................................................................... 31
3.1 Introduction ..................................................................................... 31
3.2 Brief History.................................................................................... 32
3.3 Background ..................................................................................... 33
ix
x Contents
3.4 The Vestibular System and Orientation ........................................... 36
3.5 Vestibular Sensor Function and Malfunction .................................. 37
3.6 S ensory Conflict .............................................................................. 40
3.7 T he Emesis (Vomiting) Center in SMS ........................................... 41
3.8 O ther Inhibitions in SMS ................................................................ 43
3.9 MS in SMS ...................................................................................... 44
3.10 Vestibular Angular Motion Sensors, on Earth and in Orbit ............ 44
3.11 The Emesis (Vomiting) System in MS and SMS ............................ 44
3.12 MS and SMS in Spaceflight ............................................................ 45
3.13 Vestibular Adaptation and Resolution of SMS ................................ 46
3.14 Other Vestibular Effects and Adaptations Inflight ........................... 47
3.15 Effects of Vestibular Adaptation to Weightlessness
on Return to Earth ........................................................................... 48
3.16 Variability ........................................................................................ 49
3.17 C ountermeasures, Simulations and Medication .............................. 49
3.18 R e-adaptation to 1 g ........................................................................ 51
3.19 Operational Considerations ............................................................. 51
3.20 Summary, Present and Future ......................................................... 52
Glossary.................................................................................................... 53
References ................................................................................................ 54
4 Fluid Shifts and Loss ............................................................................. 57
4.1 Introduction ..................................................................................... 57
4.2 Brief History.................................................................................... 59
4.3 Background ..................................................................................... 61
4.3.1 Circulatory Essentials .......................................................... 62
4.3.2 Circulatory Control Systems ............................................... 68
4.3.3 Examples of the Systems that Control Blood Volume
and Pressures ....................................................................... 69
4.3.4 T he Human Cardiovascular System on Earth ..................... 76
4.3.5 F luid Shifts in Weightlessness ............................................. 79
4.3.6 V olume Changes .................................................................. 81
4.3.7 Cardiovascular Changes ...................................................... 82
4.3.8 Rationale for Fluid Shift and Loss ...................................... 83
4.3.9 R eentry and Egress .............................................................. 84
4.4 Countermeasures ............................................................................. 85
4.4.1 C ontrol of Fluid Volume ...................................................... 85
4.4.2 C ontrol of leg Volume ......................................................... 86
4.4.3 An Improved Countermeasure ............................................ 87
4.4.4 Compensation for Reduced Gain of Control Loops ............ 88
4.4.5 P hysical Rehabilitation ........................................................ 88
4.4.6 I ncidence of Orthostatic Intolerance ................................... 88
4.5 Weightlessness Simulations in 1 g .................................................. 90
4.5.1 W ater Immersion ................................................................. 91
4.5.2 Bed Rest in Horizontal Position .......................................... 91
4.5.3 B ed Rest with Head Down Tilting ...................................... 91
Contents xi
4.5.4 Weightlessness in Zero-g Aircraft ....................................... 92
4.5.5 Hind Limb Unloading in Rats ............................................. 92
4.5.6 S imulation Versus Flight Results ........................................ 93
4.5.7 Summary of Fluid Shifts, Effects
and Countermeasures .......................................................... 93
4.6 The Future ....................................................................................... 94
References ................................................................................................ 96
5 Cephalic Fluid Dynamics and Ocular Changes
in Weightlessness .................................................................................... 99
5.1 Introduction ..................................................................................... 99
5.2 Brief History.................................................................................... 101
5.3 Background ..................................................................................... 103
5.3.1 The Traditional Lymphatic System ..................................... 107
5.3.2 O ne-g Phenomena Relevant to MOS .................................. 109
5.4 One-g Technology ........................................................................... 109
5.4.1 I n-flight Changes and MOS ............................................... 110
5.4.2 C ause of MOS ..................................................................... 113
5.5 Evidence Based CSF Flow .............................................................. 113
5.5.1 C SF Flow and Lymphatic Drainage in MOS ...................... 114
5.5.2 Summary of Current Status of MOS ................................... 117
Glossary.................................................................................................... 117
References ................................................................................................ 119
6 Loss of Muscle and Bone During Spaceflight ...................................... 121
6.1 I ntroduction ..................................................................................... 121
6.2 Brief History.................................................................................... 124
6.3 Background ..................................................................................... 126
6.3.1 N ature of Adaptations of the Musculoskeletal System ....... 127
6.4 Muscle ............................................................................................. 132
6.4.1 M otion ................................................................................. 132
6.4.2 F orce .................................................................................... 133
6.4.3 Muscle Fibers ...................................................................... 134
6.5 B one ................................................................................................ 137
6.5.1 Human Skeletal Bones ........................................................ 140
6.5.2 B one and Muscle Unity ....................................................... 141
6.6 Biomechanics of Force .................................................................... 143
6.6.1 M easurements in Muscle and Bone Evaluation .................. 145
6.6.2 M easurement of Muscle Function ....................................... 145
6.6.3 M easurement of bone function ............................................ 146
6.6.4 Measurement Interpretation and Application ...................... 147
6.6.5 Musculoskeletal System on Earth ....................................... 150
6.6.6 Walking, Jogging and Running ........................................... 150
6.6.7 C ycling ................................................................................ 152
6.6.8 W eight Lifting and Resistance Exercises ............................ 153
6.6.9 B one Adaptation .................................................................. 154
6.6.10 Muscle in Spinal Cord Injuries ........................................... 155