Handbook of Bioastronautics

Bioastronautics is the intersection of space science and technology with biology and human factorsHuman factors. It encompasses both human and nonhuman space life science, including astronaut performance, protection, and life supportLife support as well as the effect of space on biological processes.

Advances in bioastronautics encompassing the study and support of life in space have applications that enhance health on Earth. Clinical benefits of bioastronautics include new knowledge, approaches, and technologies for screening, prevention, diagnosis, and treatment of disease. The benefits are far-reaching and positively impact healthcare delivery from top-tier medical centers to rural communities to harsh remote environments with restricted access to medical care.

This chapter is an overview of human spaceflight-associated risks due to the space environment, which includes aspects of the space and vehicle environment and mission architecture as it relates to human health and performance. The chapter covers the Earth Orbit Environment, the Neutral Space Environment, the Space Debris Environment, the Launch Loads Environment, Acoustic and Noise Environments, the Atmospheric Environments of Space, Spacecraft, and Spacesuits, and the Reentry Environment.

Space DebrisSpace debris definition is extraterrestrial objects (meteoroids) in the Earth’s orbit and objects placed in space by humans that remain in orbit and no longer serve any useful function. Objects range from spacecraft to spent launch vehicle stages to components and also include materials, trash, refuse, fragments, and other objects that are overtly or inadvertently cast off or generated.

Environmental control and life support (ECLS) systems provide the conditions necessary to maintain astronaut's health during a mission. They have been a part of every human-rated vehicle from Mercury onward, from carbon dioxide scrubbers and drink bags, to sophisticated air and water recovery technologies. In order to enable human exploration beyond low Earth orbit for an extended time, such as a mission to Mars, closed-loop life support, the continuous use, reuse, and recycling of air, water, and waste will be necessary. This chapter provides a brief history of air revitalization, wastewater, and solid waste recovery systems from the early spaceflight era to the present, potential technologies in development to facilitate further loop closure, and considerations for future life support system development in support of exploration.

Extravehicular activity (EVA), or spacewalking, provides astronauts the capability to explore outside of the confines of their spacecraft or habitat. EVA spacesuits must provide pressurization, life support (oxygen to breathe, CO2 removal), thermal, radiation, and debris protection for the astronauts while also enabling exploration through mobile and light weight suits. EVA is a highly complex, potentially hazardous, yet critically important component of human space exploration. Failures during EVA can potentially result in loss of mission, or even loss of life; however, successful EVA enables scientific breakthroughs, advanced technology demonstrations, and iconic human achievements.

The most susceptible physiological systems to weightlessness are the sensorimotor and neuro-vestibular system controlling balance, the cardiovascular system because of lack of hydrostatic pressures, and the musculoskeletal system caused by lack of gravitational body loading attenuating muscle strength and performance as well as bone strength. The immune system is known to be attenuated during spaceflight causing viral reactivations, but the influence of weightlessness may be limited albeit present. During the last decade of spaceflight, a syndrome now termed SANS, the Spaceflight Associated Neuro-ocular Syndrome (previously VIIP, Vision Impairment Intracranial Pressure), has attracted much attention, because it may have considerable health implications for long-duration flights. In addition, the ventilation and perfusion in the lungs are changed by weightlessness leading to more even distributions, and renal function is affected and adapted to a state of attenuated excretion rates of fluid and sodium, which is probably caused by a diminished plasma and blood volume. Human physiological research in space is being conducted to acquire fundamental knowledge on how gravity affects bodily functions, and to develop countermeasures against physiological effects of spaceflight that can lead to unacceptable decrements in health and performance.

Astronauts in spaceAstronauts in space and humans aging on EarthAging on Earth experience similar changes in physiology and function; in space because they live in microgravity whereas on Earth lifestyles make less than optimal use of Earth’s gravity.

While in the space environment, healthy astronauts can lose bone mass at a rate 10-fold faster than do post-menopausal women here on Earth. Not only does bone mineral density (BMD) decline roughly 1% per month in-flight, but equally important changes occur in bone geometry and architecture that diminish bone strength and its resistance to fracture; volumetric BMD of cancellous bone at the femoral neck and lumbar spine declines even more rapidly, up to 2.5% per month. Early increases in bone resorption markers in-flight are accompanied by smaller declines in bone formation markers. The primary risk of fracture occurs when crew members transition back to the full gravity of Earth or perhaps even to the 3/8 g environment of Mars in the future. There is tremendous individual variability in the rate of bone mass loss in-flight and during recovery after return to the 1 g of Earth, which we need to understand better. Evidence to date suggests that exposure to galactic cosmic radiation, ubiquitous in the space environment, may exacerbate bone loss due to the unweighting effect of microgravity; future work needs to investigate whether continuous, long-term exposure to high energy radiation has the same effect. Current countermeasures utilized aboard ISS (resistance exercise and adequate caloric and Vitamin D intake) effectively minimize changes in BMD, but we have less information on their ability to mitigate negative changes in bone geometry. Pharmacological interventions used to treat osteoporosis on Earth may prove useful adjuncts to exercise and nutritional intake on long-duration exploration missions to protect bone integrity.

The cardiovascular system in the human body has evolved to support function in the Earth’s gravity environment involving bipedal stance and ambulation. Given that blood and body fluids are drawn downward during standing, autonomic, endocrine, and vascular responses are critical to returning blood from the lower body to the heart and perfuse the brain. Many of these functions are not required during spaceflight, and, in combination with altered blood flow and pressures, results in cardiovascular deconditioning. When not opposed by countermeasures performed during spaceflight to simulate physical work or gravity on Earth, cardiovascular deconditioning can result in low blood volume, cardiac atrophy, vascular dysfunction, orthostatic intolerance, and reduced work capacity, affecting an astronaut’s ability to perform work during and immediately after spaceflight.

Immunology defines the study of all properties of the immune system including its structure and its function, the bodily distinction between self and nonself, innate and acquired immunity, and immunization. For the host defense in health and disease, it investigates especially the relationship between invading pathogens and the triggered immune responses of the organism. Immune effector mechanisms are altered in space by the unique conditions of this perilous environment (radiation, confinement, μG) together with stress hormone-related modifications. To understand the changes that occur during short- and long-term spaceflight and to counteract appropriately to prevent disease, in-flight immune monitoring will become pivotal.

Muscle wastingMuscle wasting commonly occurs in space. The absence of gravity degrades key physiological properties of skeletal muscle. Animal and human models are helpful in understanding associated mechanisms of deconditioning and muscle atrophy.

Skeletal muscle fiber atrophy occurs in response to states of unloading such as during spaceflight (Adams et al. 2003) and ground-based analogues such as hind limb suspension and spaceflight in rodents (Caiozzo et al. 1994, 1996) and bedrest in humans (Adams et al. 2003). Unloading-induced atrophy appears to involve both components of the protein balance equation, which is defined as the ratio of protein synthesis rate divided by the protein degradation rate (synthesis/degradation rate) (Thomason and Booth 1990). When the degradation rate exceeds the synthesis rate, net protein loss (atrophy) occurs. While the equation is rather simple, the mechanisms are rather complex. The research emphasis during the past 10–15 years has focused heavily on understanding the upstream events regulating these protein processes.

Sensorimotor adaptation refers to the capacity of the central nervous system to gradually update motor control to compensate for changes in sensory inputs from the environment or for changes in mechanical characteristics of the body. One example is learning to accommodate to the refraction of light in water when reaching for objects viewed through a diving mask. In the microgravity environment, somatosensory and vestibular inputs are quite different than they are on Earth. The body is unloaded, resulting in greater movement per unit of force. Moreover, on Earth the otoliths of the vestibular system signal angle of orientation of the head relative to a gravitational vector, which is absent in space. There is a resulting reinterpretation of head tilt as a linear acceleration which leads to motor control and perceptual disruptions on return to Earth. It is perhaps not surprising then that crewmembers report a high incidence of space motion sickness due to sensory conflict. In addition, once individuals adapt movement control for the microgravity environment, these new control processes and strategies are maladaptive for Earth’s gravitational field. Therefore, there is a period of readaptation of sensorimotor control upon return to Earth which can last for days to weeks depending upon the preceding flight duration.

In this Chapter, we will present an overview of this very broad topic on how gravity shapes the structure and function of terrestrial life, from the microbiota to invertebrate and some amphibian species, and its action on selected population of vertebrate cell lines. It necessarily cannot be an all-inclusive review due to the vast amount of information gathered from these diverse domains of biological life on Earth.Of all the environmental factors under which a terrestrial organism has been exposed in the course of its evolution, only gravity has stayed constant. Predation, climate, vegetation, and terrestrial or aquatic habitation, for example, have changed, but the intensity and direction of gravity have not. The organism’s ability to detect gravity and to live under a gravitational load is critical for its survival. Even rudimentary ciliated protozoa display positive or negative geotaxis. Fossil evidence shows that the elaborate sensory structures used to sense the acceleration forces are remarkably conserved among vertebrates (Stensiö 1927). Although less is available in the fossil record on invertebrate neurosensory structures, most if not all invertebrate species can orient their bodies’ axis with respect to gravity.

As man sought to travel from the terrestrial environment, he could bring with him many things necessary for survival, but he could not bring the Earth’s gravitational field. It was expected that organisms removed from their normal ambient force environment would exhibit changes in physiology and behavior as they adapted to their new environment. Changes were expected in the “anti-gravity” systems; those designed to hold us up, move us around and circulate our fluids. And such proved to be the case. However, the multitude of spaceflight experiments conducted to date have revealed that the gravitational environment affects many systems that, at first glance, appear to have no connection to the ambient force environment. These experiments have become more detailed and comprehensive as the machinery allowing us access to space has become more sophisticated. Results from such studies are useful, not only in the design of countermeasures used to ensure astronaut health and safety, but also as they increase our understanding of the role the ambient force environment plays in the normative physiology of organisms here on Earth.

Space biomedical instrumentation (SBI) covers all devices used for biomedical monitoring, diagnosis, countermeasures, and therapy in astronauts, including relevant environmental sensors (e.g., radiation, CO2, water quality, etc.)

Stress is an organism’s response to demanding circumstances exerted by an environmental condition or a stimulus. Homeostasis is a concept central to the idea of stress. Environmental factors as well as internal or external stimuli continually disrupt homeostasis. Factors causing an organism’s condition to diverge too far from homeostasis can be experienced as stress.

One of the major concerns for astronauts on missions outside low Earth orbit (LEO) is the potential detrimental effects of space radiation. This section includes a series of articles that describe the following: the space radiation environment in unshielded interplanetary space, how the radiation environment is altered by shielding from space craft, the astronauts’ bodies themselves and other deliberately added shielding materials, the energy deposition patterns (track structures) of the ionizing particles in space and the biological importance of the tracks, and major biological impacts of those charged particles on humans, both potential acute effects that could occur during a space mission and long-term effects that might result in adverse health effects long after astronauts have completed their missions and returned to Earth. This overview briefly summarizes the information presented in the following articles.

The space radiation environment consists of highly charged and energetic particles that include high-energy protons released from the sun during solar particle events (SPEs)Solar particle events (SPEs). SPEs that are above 25–30 mega-electron volts (MeV)Mega-electron volts (MeV) can penetrate the shielding on the International Space Station (ISS)International Space Station (ISS) and present a major challenge for the National Aeronautics and Space Administration (NASA). During long-term deep space missions, it is anticipated that multiple SPEs will be encountered. Such exposures are a significant radiation hazard to astronauts and spacecraft. Indeed, exposure to SPEs may place astronauts at risk for acute radiation sickness (ARS)Acute radiation sickness (ARS), prodromal effects, skin damage, hematological/immune deficits, and changes in other body compartments. The timing of symptom onset varies with radiation dose, dose rate, quality, and individual sensitivity.

Purpose Cataracts can arise from several different etiologies due to inherent genetics, or to physiological abnormalities in an organism, or due to exposure to toxic insults. Exposure of the lens to doses of ionizing radiation (IR) greater than 2 Gy is well recognized as a risk factor for cataract. Methods This review of recent literature provides evidence for different manifestations of cataract in terms of radiation dose parameters (e.g., dose level, the ionization density of the radiation), the morphological appearance of the opacifications, and the time of presentation after exposure in human cohorts and different animal species. Molecular and cellular studies contributing to our understanding of the underlying mechanisms of action of IR-induced cataract are also discussed. Results Data show that IR-induced cataract is a progressive lesion, with several different morphological manifestations in the body of the lens during maturation of the opacification, involving multiple molecular and cellular pathways, as well as potentially direct effects on crystalline proteins. Prior work had indicated a dose threshold at 2 Gy, but with improvements in detection technologies, it is now clear that the threshold, if it exists, is 0.8 Gy or less. Conclusions Significant molecular and cellular changes occur in the lens during the latency period between lens exposure to IR and the appearance of a cataract. In April 2011 the International Commission on Radiation Protection, an advisory body providing recommendations and guidance on radiation protection reduced the recommended dose limit to the lens, not to exceed 0.5 Gy in a single exposure.

The insult from ionizing radiation to biological systems is always in the form of structured tracks of ionizations and excitations along the paths of charged particles. The track structure is primarily responsible for the potency of all ionizing radiations and for the relative effectiveness of different types of ionizing radiation. This chapter summarizes the interactions of radiation with matter and discusses microscopic features of the track structures produced by terrestrial and space radiations, with particular orientation toward the high charge and energy (HZE) particles of space radiation. Biological implications include efficient induction of complex clustered damage in DNA, as well as other correlations of damage across all levels of organization of biological system from the nanometer scale upward.

Possible acute and late risks to the central nervous system from galactic cosmic rays and solar particle events are concerns for human exploration of space. CNS risks may include altered cognitive function, impaired balance and motor function, affective behavioral changes, or accelerated late neurodegeneration, all of which may affect performance and human health. Experimental studies using accelerated charged particle beams simulating space radiation at doses below 1 Gy provide evidence for changes in rodent CNS which are persistent for up to a year. Changes in spatial and recognition memory, executive function, measures of anxiety, and motor coordination in rats and mice are observed. These are accompanied by depressed neurogenesis, altered dendritic arbors and spine numbers, elevated oxidative stress, and neuroinflammation, including microglia activation. Altered excitability, synaptic plasticity, and intrinsic membrane properties are observed in excitatory and inhibitory neurons in cortex accompanied by different levels of glutamate and GABA ion channels and neurotrophins such as BDNF. Together these changes in animals attest to the potential for impairments in human brain activity for which little or no charged particle data are available.

Several countries in the world are preparing for manned missions into deep space. However, there is a concern of potential health effects of exposure to ionizing radiation during such missions. The cardiovascular system is one of the organ systems that may be sensitive to adverse radiation effects. This entry provides a brief overview of studies in animal models and cultured cells to study the potential cardiovascular effects of space radiation and to start the identification of pharmacological or medical countermeasures against these effects.

The space radiation environment is composed of energetic electrons, photons, and all naturally-occurring atomic elements, which are fully ionized. The particle types and energies vary with location in space and depend upon the level of solar activity and the strength of local magnetic fields, such as those found around some planetary bodies. Major sources of these particles are: (1) charged particles emitted by the Sun (solar cosmic radiation), such as electrons, protons, and other light nuclei, (2) charged particles, mainly electrons and protons, trapped by planetary magnetic fields, and (3) energetic electrons, protons and heavier ions, arriving from interstellar space (galactic cosmic radiation). For the latter, kinetic energies as large as 100 EeV (1020 electron volts) have been observed. For crewed missions in low-Earth orbit (LEO), the main sources of crew radiation exposures are from Earth’s trapped radiation belts and galactic cosmic radiation. For missions beyond LEO, exposures to galactic cosmic radiation pose the greatest long-term risks, while radiations emitted in large solar energetic particle (SEP) events can result in near-term, acute health risks unless adequate shielding is available for crew protection.

The risk of radiation-induced cancer poses a serious obstacle to long duration spaceflight and planetary exploration. In space, astronauts are exposed to types of radiation not experienced on Earth. The exposures are at low dose rate, but on planned protracted missions or multiple short duration missions, the cumulative doses are large enough to pose an unacceptably high risk of radiation-induced fatal cancer. Currently, astronauts on multiple International Space Station (ISS) missions approach acceptable radiation dose limits. Projected missions such as an asteroid redirect mission or a Mars mission will exceed permissible exposure limits. Research is ongoing to accurately quantify cancer risks from space radiation and to reduce them.

In deep space, there are two main sources of energetic particles, Galactic Cosmic Rays (GCRs) and sporadic Solar Particle Events. The energetic particles that are abundant among the GCRs span the range from hydrogen nuclei (protons) to iron nuclei, with a range of kinetic energies spanning many orders of magnitude. Higher-energy GCRs can penetrate depths of shielding far greater than can be launched into space owing to the high cost of launch. SPEs typically produce lower-energy particles against which moderate depths of shielding suffice. Because of the high energy of many of the GCRs that impinge on a spacecraft and the complexity introduced by their interactions in spacecraft materials, crew members receive radiation doses at rates two to three orders of magnitude greater than those received on Earth. These doses are likely not enough to cause biological effects that would manifest during a mission, but are a concern for causing so-called late effects, such as cancers that could manifest in the years following a mission. This chapter describes the space radiation environment and the physical processes that occur when high-energy particles undergo electromagnetic and nuclear interactions with matter; these are the mechanisms by which bulk matter may provide some degree of shielding against space radiation. Brief descriptions are given of magnetic and electrostatic shielding that might be used to protect astronauts; both present extreme technical challenges that have not yet been met, leaving bulk shielding as the most likely option to be used in the human exploration of deep space.

This overview of the behavioral health and performance chapters provides a perspective on the challenges to behavioral health and performance posed by spaceflight and the lessons learned from the history of terrestrial and spaceflight expeditions, as well as the key role of assessing cognitive functions in spaceflight, ensuring adequate sleep and circadian entrainment in spaceflight, and maintaining a system to manage behavioral health in prolonged spaceflight.

The effects of living and working in isolation and confinement on human behavior have been described by explorers and studied by scientists. This chapter summarizes efforts to derive lessons from expeditions of the past and from other space-analog experiences that might be applied to facilitate adjustment and sustained human performance during future long-duration space missions.

Sustained high level of astronaut cognitive performance is critical to increase the likelihood of space mission success in the face of several environmental, physiologic, and psychological stressors related to living for prolonged periods in an isolated, confined, and extreme (ICE) environment. This chapter briefly reviews domains of cognitive performance and recent advances in computerized cognitive testing that links to brain networks established with functional neuroimaging. It then discusses studies on the effects of living in ICE environments on cognitive performance in both spaceflight and space analog environments. Gaps in knowledge are identified and directions for future research are offered.

It is important for space crews to have good interpersonal relationships and open channels of communication. Crewmember interactions can be affected by factors inherent in the mission itself, by individual differences, and by group issues related to culture and family. Good interactions can improve morale, well-being, and the accomplishment of mission goals. Poor interactions can lead to group tension, lack of cohesion, withdrawal and territorial behavior, subgrouping and scapegoating, displacement of negative affect to others, and improper use of leadership. By understanding these interactive issues and developing ways of selecting and training crewmembers to relate better with one another, the chances for mission success are improved, and space travelers can have a more positive experience during their journey.

This chapter focuses on describing the behavioral health activities and services provided to the NASA United States’ astronauts by the Behavioral Health and Performance Group at Johnson Space Center, Houston, Texas. Using the disciplines of aerospace psychology and aerospace psychiatry, the Group’s activities include astronaut selection, astronaut training, providing clinical services to the astronaut and their immediate family, and psychological support to the astronaut during all phases of their mission on the International Space Station.

Space operations are extraordinarily challenging endeavors, demanding high cognitive performance and alertness from both astronauts and ground-based crew. Due to the nature of the space environment and mission constraints, it can be difficult to entrain, or align, the body’s internal ~24.2-h circadian rhythm to the required day length (e.g., the 24-h Earth day or the 24.65-h Mars day), to adapt to shifts in sleep/wake or work schedules, and to obtain sufficient sleep. Both circadian rhythms and sleep physiology significantly affect human performance, alertness, mood, and other physiology. To address these concerns, mathematical models of human circadian rhythms, sleep, performance, and alertness have been developed. These models can be used to predict how individuals will function on different schedules, to suggest strategies to improve performance, to entrain circadian rhythms, and to optimize the use of countermeasures such as light, naps, and pharmaceuticals. These models are also applicable to other settings where individuals face difficulties entraining or shifting their circadian rhythms, such as shift-work, or where performance failures present a high risk, such as aviation, healthcare, security, and transportation.

This chapter describes how spaceflight impacts the quantity and quality of nightly sleep and how the misalignment of the sleep-wake schedule with the circadian timing system affects sleep and the use of fatigue countermeasures.

An overview of spaceflight analogs for bioastronautics concerns itself with terrestrial space life sciences platforms. A “terrestrial space life sciences platform” is defined here as any facility, technology, or method that allows for simulation of certain aspects of the spaceflight environment.

A lower body negative pressure (LBNP) device is an airtight chamber surrounding the legs and pelvic area. LBNP has been used for decades as a research tool and more recently as a countermeasure during spaceflight; the negative pressure simulates the effects of gravitational stress by displacing blood and tissue fluid towards the feet while simultaneously inducing mechanical loading and ground reaction forces under the feet. LBNP is currently considered the most promising countermeasure to maintain structure and function of eyes and brain, while the combination of LBNP and exercise could potentially provide additive effects to also maintain exercise capacity and cardiovascular and musculoskeletal health during long-duration spaceflight.

An upright lower body positive pressure (LBPP) device is an airtight chamber encompassing legs and pelvic area; as pressure in the chamber is increased, the person is lifted, thereby reducing bodyweight at the level of the feet (Fig. 1).

Sustained weightlessness is only achievable during spaceflight. However, very short duration weightlessness can be created within the Earth’s atmosphere by allowing an airplane to follow a parabolic flight trajectory which includes a free fall period symmetrical around the top of the parabola. Because all resultant forces acting on the airplane, such as thrust, drag, lift, and gravity on the airplane, cancel each other out, true weightlessness is achieved for the duration of the free-fall maneuvers. The weightlessness phase is preceded and followed by periods of hypergravity induced by acceleration (pull-up phase) and deceleration (pull-out of the fall phase).While the bouts of weightlessness are short-lived, usually 25–35 s, they are reproducible and can be performed many times in a series. Parabolic flight is therefore a cost-effective tool in research aimed at both physics, materials science, and human physiology, as well as for astronaut training. Some limitations apply due to the hypergravity phases and the short duration. Several parabolic flight platforms are currently operational in many countries across the world, managed by various national space agencies or interest groups and utilizing airplanes ranging from large passenger jets to small two-person airplanes.

Experiments in hermetic chambers with crew isolation simulate effects of long-term spaceflight, such as sensory deprivation, monotony, confinement, social deprivation, and controlled artificial environment, to study their influence on crew members’ behavior, activity, psychophysiological state, and interactions.Chamber studies allow: Implementation of complicated inflight research protocol and equipment testing for a particular space expedition (e.g., HUBES-94) Examining phenomena discovered in spaceflights in more detail and with the most advanced methods (e.g., ECOPSY and SFINCSS) Simulating important possible features of future missions (e.g., MARS-500)

The primary objective of the countermeasures program is to maintain crew functionality on long duration spaceflights (LDS). All International Partners (IPs) contributed to this effort. Russia’s Institute for Biomedical Problems (IBMP) and NASA’s Human Research Program (HRP) had major responsibility for overall countermeasures. The focus of this section is physical countermeasures; primarily modes of exercise. This material summarizes equipment types and protocols utilized during the initial 10 years of ISS operations. The results presented were obtained by assessing crew performance pre and post flight.

Space biology facilities refer to physical capabilities aboard spacecraft that allow for an increase in our understanding of biological processes in microgravity. These can be in vitro processes in cell-free and cell-based investigations and in vivo research in living hosts (cells and bacteria, worms, insects, fish, birds, reptiles, amphibians, lagomorphs rodents, and lower primates). Facilities can be habitats, storage, analytical testing equipment, specimen storage, low temperature conditioned storage, isolation facilities, and accommodations for veterinary medicine. The refrigerator/freezer facility is described in this overview because it is so critical as an adjunct to the many other facilities for plant and animal research described elsewhere in this report.

A bioreactor is an apparatus in which biological processes are performed under controlled conditions. Space bioreactors refer generically to much of the equipment that accommodates biological processes regarding the maintenance and culture of cells in space. The microgravity of space as well as other physical aspects of space travel offer a unique environment in which terrestrial life as modeled in bacteria and cells display their unique fundamental mechanisms of adaptation to microgravity as well as environmental changes caused by microgravity. Understanding these adaptations opens a new platform for development of novel opportunities in bioscience, biotechnology, and bioengineering. Indeed the elucidation of these fundamental mechanisms will allow discrimination of the indirect mechanisms of life responses to microgravity-induced changes in the cell culture environment from direct responses of the cell to the intensity of the gravitational force (e.g., an intrinsic cellular gravimeter).

Centrifuges running in weightlessness simulate gravity for biological experiments in the space environment, either for a reference experiment or as a gravity stimulus.

Space medicine is a branch of medicine that deals with the biological, physiological, and psychological health effects and medical problems of flight personnel in the context of spaceflight. This chapter provides a short introduction to the entries in the section “Space Medicine” and outlines the roles and training of the flight surgeon.

In this chapter, the history of medical screening standards for the selection and retention of professional astronauts is examined. The evolving views on risk and human factors are discussed in their relationship to changing screening and selection criteria, and current selection standards are discussed.

The term “research” refers to a class of activities designed to develop or contribute to generalizable knowledge. The fact that NASA was conducting and planning future human research required that it develop an institutional review board (IRB). Formal bioethics policies and procedures started with the establishment of the Johnson Space Center (JSC) IRB, which was known as the Human Research Policy and Procedures Committee (HRPPC). It was developed in response to NASA NMI 7100.8 in 1972 (DHHS 1974). The Belmont Report (1979) required updates to NMI 7100.8. This chapter traces the evolution of NASA’s human research guidelines through the International Space Station. Finally, some considerations of exploration class missions are discussed.

This chapter is an overview of the most prominent illness occurring in spaceflight or related to spaceflight. These conditions include space motion sickness (SMS), decompression illness, urologic conditions, including kidney stones, orthopedic conditions, skin disorders, otorhinolaryngology problems, eye changes, gastrointestinal issues, sleep disturbances, psychological disturbances, headaches, cardiac abnormalities, toxin exposures, and trauma. Detailed examination of the pathophysiology and diagnostic workups is not discussed.

As it pertains to space travelers, the term “nutrition” encompasses many things, including the body’s basic need for nutrients. The amounts of nutrients required for optimal health can be affected by aspects of the environment, including gravity, radiation, temperature, and humidity. Nutritional requirements can be further altered by effects of microgravity on the body’s absorption, processing (metabolism), and excretion of nutrients. “Nutrition and metabolism” also encompasses the interaction of nutrients with the biochemical pathways (metabolism) by which physiological systems, such as bone, muscle, and cardiovascular systems, and even behavior and performance, accomplish their functions.

“Operational space medicine” is the term used to describe the clinical practice of a flight surgeon as that practice relates to the care of spaceflight crew members. It encompasses pre-flight, in-flight, and post-flight activities. It draws upon the terrestrial disciplines of occupational medicine, wilderness medicine, and family practice and adds many unique aspects as described in this section (Bacal and Lemery 2007; Nicogossian and Parker 1982).

This chapter will discuss the challenges of suborbital and orbital commercial human spaceflights, the recommended medical standards and management of medical risks, and the inform consent process applicable to the launch, flight and landing. Spaceflights are associated with a number of physiological and psychological changes that may cause and/or aggravate certain medical conditions during flight, and could adversely impact an individual’s health and safety. The spaceflight environment is far more hazardous compared to the operational risks encountered during commercial aviation flights. Such increased risk factors include: acceleration, barometric pressure, microgravity, ionizing radiation, non-ionizing radiation, noise, vibration, temperature and humidity, breathable air and ventilation, as well as behavioral issues. The main challenge for Aerospace Medicine Specialists is to identify and mitigate significant pre-existing diseases, illnesses, injuries, infections, treatments (pharmacological, surgical, prosthetic, or other), or other physiological or pathological or psychiatric conditions among commercial space vehicle occupants (flight crews and passengers). These medical conditions have the potential of resulting in inflight medical emergencies, resulting in inflight deaths, compromising the health and safety of commercial space vehicle occupants, interfering with the proper use (don and doff) and operation of personal protective equipment, interfering with emergency procedures (including evacuation), and/or compromising the safety of the flight. Therefore, prospective commercial space vehicle occupants will have to be medically evaluated very carefully before allowing them to participate in suborbital and orbital spaceflights.

Visual impairment associated with extended spaceflight is NASA’s number one human spaceflight risk. The syndrome, known as spaceflight-associated neuro-ocular syndrome (SANS), was earlier referred to as visual impairment intracranial pressure (VIIP). The syndrome, which follows microgravity exposure, manifests with changes in visual acuity (hyperopic shifts) and in eye structure (optic disc edema, choroidal folds, globe flattening, and distended optic nerve sheaths). In some cases, elevated cerebrospinal fluid pressure has been documented following spaceflight, reflecting increased intracranial pressure (ICP).

This chapter focuses on the history of US space exploration from the 1950s into the twenty-first century, highlighting the four major flight programs – Mercury (1961–1963), Gemini (1965–1966), Apollo (1967–1972), Space Shuttle (1981–2011) – and the two extended orbital workshops, Skylab (1973–1974) and the International Space Station (2000–present). In addition, recent developments in space tourism and other commercial space activities are profiled.

In this chapter, highlights of human spaceflight are summarized achieved in the frame of the microgravity programs funded by the European Space Agency ESA and/or the German Space Agency DLR. After describing the historical context, thereby stressing the importance of cooperation with the USA and the Soviet Union/Russia especially in the ISS era, specific programmatic aspects in Europe are briefly explained. The major part of the chapter provides examples for scientific accomplishments and discoveries in space biology and medicine obtained over the last decades focusing on a completely new view on hypertension established by space and accompanying ground-based research. The last part of the chapter describes important technological developments in the area of noninvasive medical diagnostics, therapy, and rehabilitation. Impressive examples demonstrate the successful transfer of devices and methods developed for space life sciences into the commercial market for the benefit of people on Earth especially in the aging society.

China has a distinguished record of successful manned and unmanned space activities. These include a space station and a growing program of lunar landers leading toward lunar exploration.

This chapter focuses on the activities in space medicine research and life science experiments, including biology and human research in Japan from the 1960s toward 2020s, and highlights on-orbit experiments utilizing the space environment, Space Shuttle, and the Japanese Experiment Module (JEM) “Kibo” attached to the International Space Station (ISS).

Astrobiology is the study of the origin, evolution, distribution, and future of life in the universe, and so has life at its core. It asks some of humanities most profound questions: Where does life come from? Where is it going? Are we alone?

This chapter is an overview of human spaceflight-associated mishaps and incidents and also describes human health threats involved with spaceflight. Humans flying is space have historically had a higher risk compared to comparable humans engaged in aviation operations, particularly fatal mishaps (loss of crew) per mission sortie (launch/landing). Historical loss rates in suborbital winged reentry vehicles (X-15) is approximately 1 in 100 sorties, and in orbital flight, both blunt capsule (Soyuz) and winged vehicles (Space Shuttle) was approximately 1 in 70 sorties, while civilian general aviation fatal mishaps are 1 in 100,000 sorties, while in regulated airline flights the fatal rate is approximately 1 in 10 million sorties. Fatal space mishaps historically have occurred during high energy transition states (launch/ascent) where chemical energy is converted to kinetic (airspeed) and potential energy (altitude), as well as reentry/landing where potential (altitude) and kinetic (airspeed) are converted to thermal energy (reentry heating). All phases of flight from launch, ascent, on-orbit, and reentry and landing and post-landing all have risk associated with them. As risk is quantified by consequence (outcome) times duration, the on-orbit portion, being longer than the launch and reentry period, is also of concern, as even minor conditions can worsen over time. Specific risks include the space environment, such as radiation, the vehicle environment, and the mission architecture. For commercial space operations, informed consent is a mandatory requirement for spaceflight participants to recognize and understand.

In this chapter, the history of mishaps and accidents within the US space program is examined in order to provide context and understanding of how mishaps occur, ways in which they can be prevented or mitigated, and identify common factors therein. In particular, this chapter identifies the role of human error, on the part of the crew and the support teams, and how human influence can alter the risk of mishap both positively and negatively.

The Soviet Union (Russia) was the first country to launch humans into space with the launch of Yuri Gagarin on April 12, 1961. This chapter reviews of human spaceflight associated mishaps and incidents launched by Russia (former Soviet Union) and their human health threats involved with spaceflight. The mainstay Russian launch system is the Soyuz spacecraft that has been used since 1967 in its six iterations (Soyuz 7K, T, TM, TMA, TMA-M, and its latest MS variant). Human spaceflight owes much to the Russian Space Program as it implemented previously untried means to launch and keep humans alive. The Russians, having chosen space stations in Low Earth Orbit rather than a lunar program, rapidly set all the long duration records, most of which still hold today. The Russians have three cosmonauts who have exceeded 1 year for a single mission. Russian cosmonauts’ cumulative totals include three with over 800 days in space, another three with over 700 days in space, and another three with over 600 total days in space. The early Russian space program had its share of significant incidents including launch abort, ascent abort (most recently in Oct 2018), combustion, depressurization, toxic atmosphere, medical and psychologic events, three early mission terminations and three other near evacuations, as well as entry and landing and post-landing events. There two fatal mishaps, Soyuz 1 in 1967 and Soyuz 11 in 1971, resulted in four lost cosmonauts. Lessons learned from mishaps have contributed significantly to improved safety and reliability in human spaceflight.

Human Space Exploration beyond low Earth orbit could include a return to the moon, exploration of Mars, and stay in cis-lunar space and at Lagrangian points, as well as exploration of asteroids.

Near Earth Object (NEO) NEOs include comets, asteroids, and meteors that have been affected by the gravitational attraction of nearby planets and directed into orbits that allow them to be considered “near” the Earth (i.e., within 45 million kilometers of the Earth’s orbit). NEOs are widely varied in size from centimeters to kilometers in diameter (NEO Program JPL 2015a; Abercromby et al. 2013).

Aphelion The point on an elliptical orbit around the sun that is farthest from the sun. Communication latency The time it takes for a signal to travel from the sender to the receiver, typically in reference to radio communication. Free return A trajectory through space that brings a spacecraft back to the Earth without any major propulsive course changes. Habitable volume The amount of volume available to the crew for living and working. Does not include space behind panels, underneath equipment, or otherwise inaccessible to the crew. Hohmann transfer An elliptical path that takes a spacecraft from one circular orbit to another of larger or smaller diameter with the minimum amount of propellant used. Perihelion The point on an elliptical orbit around the sun that is closest to the sun. Planetary protection Preventing both the contamination of potentially habitable environments on celestial bodies by organisms from Earth and the contamination of the Earth’s biosphere by organisms from space. Regenerative life support A system that recycles air, water, and possibly also food on board a spacecraft, as opposed to a system that relies on massive stores of consumable commodities. Superior conjunction The condition that occurs when the sun lies directly between two planets, as described by an observer on the planet farther from the sun.

Current human space programs are focussed on the Moon. The United States plans a return, China has a burgeoning program, India is developing human spaceflight, and the International Space Station partners remain committed to future developments. But the political future of human spaceflight is uncertain – national goals come and go and there is no current strong geopolitical driver. Human spaceflight to Mars remains a strong notional goal, but in contrast to robotic development there are still strong technological uncertainties to human flight to Mars and beyond. Artificial intelligence, robotics, and increasing miniaturization in space technology may lead to human space exploration to be more virtual, with roles for human crews minimized or even located on Earth. Whatever the future, it is certain to be international, multinational, possibly even with private players and with a strong mix of robotic development.

Balloons have had in instrumental part in many aspects of human flight in both aviation and space. Humans first left the surface of the Earth in 1783 in balloons, and rapid advances in high-altitude physiology were made in the following century as well as recognition of the grave dangers associated with high-altitude exposure. Balloons have advanced many scientific endeavors including space radiation research, atmospheric and climate science, and Earth observation. Arguably the first “Space Race” occurred in the 1930s with stratospheric balloons. Prior to humans launching into space, balloons were used as a space analog flying missions over 24 h above 100,000 ft. Balloon technology continues to advance to this day, and stratospheric balloons continue to be a viable testbed for life support systems and crew escape tests as well as use as a first stage for sounding rockets. Commercial companies are targeting “Near Space” human stratospheric balloon flights for tourism and scientific research.

There are many reasons for sustained human return to the Moon. These include scientific, development and operational considerations, which are described in this chapter. In addition, lunar exploration would be inspirational to the next generation and contribute to national prestige of participating nations.

This chapter describes major challenges and opportunities associated with transferring bioastronautics knowledge among space faring nations. It highlights select programs at the elementary school through postdoctoral levels, including medical and military training, that promote bioastronautics and broader science, technology, engineering, and mathematics (STEM) literacy, particularly in Africa. The chapter also examines bioastronautics knowledge transfer partnerships among commercial space organizations and national space agencies (MacLeish et al., International cooperation for space life sciences knowledge sharing and development in Africa. International Academy of Astronautics, Paris, 2014).The coordinating theme is that educational outreach is essential for transferring bioastronautics and STEM knowledge in support of the emerging global consensus that (1) space exploration’s ultimate mission is to serve humanity and (2) international partnerships are a primary mechanism for accomplishing this missing (Pace et al. 2010). Education modules and programs selected for discussion cover multidisciplinary topics, including the nature of the space environment, student experiments on the International Space Station, and impacts of space travel on the human body (e.g., sleep circadian rhythm interruption; bone loss; radiation exposure; and brain, muscle, neurovestibular, and cardiovascular alterations). Science and engineering coursework, clinical experiences, space-related research apprenticeships, and research projects are the major foci at graduate and undergraduate levels. Military training programs are limited in number and scope, but they are included because they offer a unique pathway for developing specialized bioastronautics skills among professionals, including astronauts and scientists. The chapter also includes a brief discussion of multimedia scientific literacy outreach programs delivered by museums, science centers, and radio/television outlets.Educators and other science literacy disseminators across the globe are challenged in weaving new bioastronautics information into their respective outreach programs. The chapter’s detailed description of partnerships among educators, scientists, and non-academic or informal education communities illustrates the key role that such collaborations play in bridging the bioastronautics knowledge/STEM literacy gap and in producing innovative classroom materials that are indigenous to diverse cultures and efficacious for use in classrooms worldwide. This section also provides an overview of global bioastronautics careers and discusses strategies employed by various governmental/nongovernmental entities to introduce bioastronautics education into their respective countries’ curricula [ENQA] European Association for Quality Assurance in Higher Education (Standards and guidelines for quality assurance in the European higher education area, Brussels, Belgium. ENQA, Brussels, 2005) Standards and guidelines for quality assurance in the European higher education area, Brussels, Belgium.

K-12 education programsK-12 education programs – Selected NASA and international education programs (curriculum materials and events) suitable for kindergarten students through precollege students in the 12th grade

This section describes a pedagogical framework for establishing a comprehensive curriculum that incorporates bioastronauticsBioastronauticsdefinition – the study and support of life in space – into academia and also lists currently identified educational programs that offer or plan to offer coursework in various topics related to this field of study.

The chapter describes select medical schools in the United States (US) and Europe that conduct research and specialized training in bioastronautics science and space medicine. These programs illustrate the key role that medical schools play in producing countermeasures to the health-related problems and physical and psychological challenges men and women will face on long-duration missions. Also, medical school bioastronautics disciplines are leading the way for scientists and physicians to develop technologies that provide medical monitoring, diagnosis, and treatment in the extreme environments that space explorers will face during exploration missions. These discoveries have potential to impact medical care on Earth by transferring the solutions to patients suffering from similar conditions, including osteoporosis, muscle wasting, shift-related sleep disorders, balance disorders, and cardiovascular system problems.Medical schools with formal bioastronautics research and training programs engage medical specialties to examine the effects of spaceflight on humans, identify risks, and prevent problems that humans face while living in the extreme environment of space. These risks include exposure to the hazardous environments of space and medical challenges – sleep and circadian disorders experience in space exploration, behavioral, mental and physical risks, among others – that have potential to affect crew health and mission success (IOM, Health standards for long duration and exploration spaceflight: ethics principles, responsibilities, and decision framework. Institute of Medicine Report, 2014). In general, these medical bioastronautics programs utilize multidisciplinary teams of physicians, space scientists, and engineers to study the physical, mental, and social health of humans in space, on their return to Earth and to spin off products for commercialization.Many medical school bioastronautics programs collaborate with complementary graduate education research programs to broaden understanding of the systemic nature of spaceflight risk mitigation. These programs, which include governmental and nongovernmental space organizations and graduate/undergraduate level academic research departments, provide graduate and undergraduate level space science and engineering coursework, clinical experiences, space-related research apprenticeships, and research projects.

Internships, fellowships, residencies, and other relevant opportunities that provide experiential scientific experiences and mentoring to students and postgraduates, pursuing careers in the space biomedical sciences.Increasing retention among students and postgraduates in scientific fields has become imperative to 0 consistent and stable growth within the space biomedical sciences. To address difficulties recruiting a new generation of skilled professionals, many entities have initiated internship programs, fellowships, and residencies intended to generate interest in space biomedical science careers. These interventions are both immersive and intensive, encouraging exceptional young scientists to explore more rigorous and thought-provoking careers.

This discussion covers how space-based museums and science centers increase science literacy, promote public appreciation for/understanding of bioastronautics education, and publicize the relevance and benefits of space exploration to life on Earth. Globally, these institutions are considered essential for educating scientifically literate publics, and they are deemed central to the global astronautic vision that space exploration enhances our understanding of Earth and the universe, while also producing benefits for future generations (IAA, 2010). Space museums and science centers differ from traditional museums, which have existed for centuries to preserve and provide access to culture and objects of art. Private museums often have specialized missions, while multidisciplinary museums, such as the American Museum of Natural History, may have broad mandates ranging from exhibits on dinosaurs to IMAX films and space shows in their planetariums. Space museums and science centers also may offer a wide variety of experiences covering space and aviation history, technology-driven exhibits, and multimedia programs that interpret space exploration science and translate bioastronautics research for their respective audiences. They collaborate with the full spectrum of educational institutions – from elementary through postgraduate levels –to create new space-related materials and promote deeper understanding of science, technology, engineering, art, and mathematics (STEAM) fields. Many space museums are funded by both governmental and nongovernmental entities and serve wide-ranging constituencies – students, teachers, families, and general populations – through an array of activities, including multimedia productions (e.g., television, film, radio, web-based), topical exhibits, teacher professional development programs, and summer/after school education programs (MacLeish et al., Acta Astronaut 63:1158–1167, 2008).

The personal recollections of physiological changes during and after spaceflight are summarized by an astronaut who made five trips to space on the Space Shuttle (Fig. 1).

Performing life science research in space during the Shuttle program was not easy. While there was great promise for scientists interested in understanding the effect of gravity on living things, the path was daunting and required perseverance, patience, ingenuity, flexibility, and compromise. Experiments on the Shuttle were expensive, and the number of data points and repetitions was often quite limited. This is a personal perspective of that arduous yet rewarding journey during my career as an astronaut from 1978 until 1996.