Thriving in Space Ensuring the Future of Biological and Physical Sciences Research: A Decadal Survey for 2023-2032 (2023) / Chapter Skim
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4 Science to Enable Space Exploration
4 Science to Enable Space Exploration
Pages 93-132
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This chapter focuses on the key scientific questions (KSQs) that need to be answered in the coming decade to enable space exploration, including the rationale and possible research areas that support such investigations.
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Table 4-1 summarizes the KSQs presented in detail in Chapter 4, addressing two of the three themes of this decadal survey. These two themes focus on research outcomes that will enable space exploration in the decades to come.
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Answers to questions posed in this chapter will be important to close that gap of data and knowledge over the coming decade. BPS KEY SCIENTIFIC QUESTIONS THEME 1: ADAPTING TO SPACE -- OPTIMIZING BIOLOGICAL ADAPTATIONS FOR SURVIVING AND THRIVING IN THE SPACE ENVIRONMENT Many gains were made over the past 60 years of space exploration in understanding how organisms, including humans, physiologically adapt to relatively short stays in the space environment (Afshinnekoo et al.
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The committee sees potential for significant advances in space exploration if a biological and physical sciences portfolio in the coming decade is aimed at understanding • Biological responses that occur during transitions between the Earth and space environments over extended duration and distance to fundamentally enable space exploration; • Genetic diversity to understand positive and negative responses and long-term adaptations to spaceflight to accelerate the identification of risks, mechanisms of adaptation, and potential positive adaptations that could improve life in space; and • How cells, systems, and organisms concurrently adapt to the spaceflight environment and develop mechanisms for encouraging positive and countering negative communicated responses. Question 1: How Does the Space Environment Influence Biological Mechanisms Required for Organisms to Survive the Transitions to and from Space, and Thrive While Off Earth?
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. Understanding such adaptations in more depth is necessary for optimizing survival of organisms during space exploration, especially beyond LEO.
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The reduced hydrostatic pressures and mechanical loading couples the cell interactome, the local microenvironment, and global transport processes to produce the observed mechanistic and functional changes. Other ways that fluid shifts disrupt mechanisms that arise in living systems are by controlling thermodynamics, reaction kinetics, and transport processes.
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The effects of fluid shifts in microgravity are complex; microgravity will alter hydrostatic pressures, flow, and mechanosensory pathways that drive changes in overall maintenance, growth, and repair processes. Potential Research Areas -- Fluid Shifts How do shifts in fluid dynamics impact the movement and metabolism of molecules?
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. Understanding how fluid shifts affect growth and plant structures will help identify gene pathways for enhancing plant growth.
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Analyses of findings indicated significant effects on metabolic genes, which would be expected to directly and indirectly impact all tissue types. In mouse models, lipid metabolism and liver function have also been shown to be impacted by the spaceflight environment (Beheshti et al.
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. Biological Mechanism -- Structural Biology and Wound Responses Wounds can occur during space exploration, including internal wounds often associated with bone fracture.
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Because wound responses are seen in plants in spaceflight, even in the absence of actual wounding, increased knowledge of the plant defense responses may reveal the overall principles involved in recognition of tissue damage in space and the repair mechanism enacted as a response to that perceived damage. Indeed, analogy to other organisms including extremophiles has the potential to provide Earth-based knowledge that can be applied to enabling space exploration.
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of exploration class missions and the opening of opportunities for more humans to travel in space owing to privatized spaceflight, it is increasingly critical to understand if and how preexisting chronic conditions that may go undetected before launch will impact on that individual's health and performance in the space environment. Genetic Diversity in Spaceflight Response Two decades ago, the only astronaut health issue for which a large enough data set exists to allow valid conclusions to be drawn about gender differences was orthostatic intolerance following shuttle missions, in which women have a significantly higher incidence of presyncope during stand tests than do men (Harm et al.
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and will contribute to evaluations of genetic diversity in a model grass species that will be relevant to future exploration agriculture. In the spaceflight environment, genotypic variation in Arabidopsis impacts the plant's ability to adapt.
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In addition to the genetic diversity approach to examining the physiological adaptation to spaceflight, an approach particularly important for plans is understanding the pathways to implementing that genetic information to produce biological systems that directly support space exploration. How best to deploy the currently available genetic information to producing strains that better support exploration?
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2019) , which provided a unique opportunity to compare molecular profiles of identical twin astronauts, revealed how the structure and function of numerous physiological processes are altered by space exploration (e.g., changes in DNA methylation, telomere length, immune response, microbiome, biochemistry, and metabolomics)
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Impact on Extracellular Molecules and Extracellular Vesicles Extracellular vesicles are prime candidates for cross-talk vectors, and their study in organisms in space is critical for an understanding of the biological effects of the space environment. Extracellular molecules are the communicators in intra-organism cross talk and can be either small molecules, protein-based, or nucleic acid– based.
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Identification of extracellular molecules and extracellular vesicles secreted during spaceflight or planetary life is the first step in understanding key cellular cross-talk mechanisms. Potential Research Areas -- Extracellular Molecules and Extracellular Vesicles What are the downstream phenotypic consequences of this crosstalk as altered by the space environment?
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. An enhanced understanding of how the stressors associated with deep-space environments impact microbes, their disease-causing properties, and their susceptibility to treatment with antimicrobials will be important to enable deep-space exploration (Tierney et al.
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Additional studies evaluating the genomic and physiological effect on plants after controlled pathogen infections will show if any altered mechanisms of pathogenesis are unique to the spaceflight environment. Zinnia plants growing in the Veggie unit, which were under an excess water stress, were highly susceptible to infection by an opportunistic fungal pathogen Fusarium oxysporum (Schuerger et al.
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(See Figure 4-7.) The theme of Living and Traveling in Space fully integrates the biological and physical sciences in enabling space exploration, including a completely integrated system of biology encased within unique physical systems, which is seeking to eventually thrive without resupply.
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• What principles enable identification, extraction, processing, and use of materials found in extraterrestrial environments to enable long-term, sustained human and robotic space exploration? Resources from planetary materials, atmospheric, and mission wastes can all be captured and harnessed for production of mission-critical/high-value chemicals, materials, and biological feedstocks.
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Recommendation 4-3: To ensure the long-term survival of life in the spaceflight environment, NASA should ramp up investigations into space impacts on sustained human presence in space by investigating: • Reproduction, development, and evolution within all relevant biological systems; • The relationships between biology and space hardware to ensure structural integrity, optimized recycling, and utilization of local resources; • Effective chemical, physical, and biological methods for locating, extracting, and processing local resources, especially from the Moon, for use in local habitation and downstream production; and • Fluid physics, combustion, and related sciences to enable sustainable space exploration and habitation. Question 4: What Are the Important Multi-Generational Effects of the Space Environment on Growth, Development, and Reproduction?
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Over the past decade, an increasing number of studies have discovered spaceflight-induced epigenetic alterations in a variety of biological organisms in LEO.5 Given the added impacts of long-term radiation exposure in spaceflight during deep-space exploration, it is expected that there will be generational effects in long-duration space habitation. Owing to generation times and the opportunities and needs for reproduction, the generational effects of spaceflight are most likely to be seen in microbes, plants, and other organisms with short life cycles (e.g., worms and flies)
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The resulting increased understanding the microbial responses of key species to ambient and engineered spaceflight environments will be imperative for supporting robust biological life support systems in future surface habitats on the Moon or Mars. These experiments can leverage new advances in multi-omics profiling and sensor technologies, as well as classical microbiological analyses, to obtain a more complete view of any changes that occur in space relative to ground control.
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Which microbes most efficiently enable fermentation as a nutrient preservation measure in space environments? How does the spaceflight environment influence microbial community dynamics and the ability of members of microbial communities to coordinate their metabolism toward carrying out key metabolic processes, such as nutrient cycling?
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Therefore, it is important to study the multi-generational effects of the space environment on plants. Potential Research Areas -- Plants How does the spaceflight environment influence pollination/fertilization and seed development/viability of various crops over multiple generations, and what strategies are needed to ensure continuous crop production?
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Understanding the role of epigenetic modifications in the spaceflight environment has practical application to exploration needs. In terrestrial environments, acquired DNA methylation patterns can transfer to the next generation, where they may contribute (Heard and Martienssen 2014)
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from different space environments can impact both engineered systems and native biological systems, as well as their interactions. In biological systems, synthetic biology has been proposed to help overcome challenges associated with longterm deep-space exploration (Llorente et al.
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FIGURE 4-9 Examples of biological and abiotic system interactions that are potentially altered by space environments. Biological and abiotic systems likely interact in the space environment, although principles and opportunities of interaction are not yet well understood.
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It will be critical to identify, prevent, and mitigate any potential harmful effects or byproducts associated with biological organisms in space habitats (Nickerson et al.
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(See Figure 4-10.) How will the spaceflight environment impact the interaction between microbes and the surfaces of the built environment (i.e., a space, lunar, or Mars station)
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How does the spaceflight environment impact the microbes of the built environment (MoBE)
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Question 6: What Principles Enable Identification, Extraction, Processing, and Use of Materials Found in Extraterrestrial Environments to Enable Long-Term, Sustained Human and Robotic Space Exploration? Impact and Rationale Exploration and long-term sustained presence beyond Earth will be enabled using planetary surfaces, materials, and environment, particularly for ISRU.
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Additive manufacturing with lunar regolith when there is a binder phase would be less energy intensive because the lunar regolith would not be sintered. However, binder feedstocks generally cannot be sourced from the lunar environment, although plastic waste can be converted to binders for some of these additive manufacturing methods.
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Because damage will inevitably arise, repair methods need to be considered, and these need to be flexible with regard to materials and able to shape materials on demand because the ability to carry spare manufactured parts is limited. Thus, flexible methods for forming and/or placement of various materials is an essential engineering science research direction to enable space exploration.
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In fact, any research benefits long-term space exploration, but also sustainability on Earth. Propellant production under partial gravity is of particular interest on Mars and the Moon and a key enabling method to increase the range of space travel.
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Thus, fluids in space environments are critical to biological functions, engineered materials processing, and safe transportation, but can confound expectation and prediction based on Earth-based fluid dynamics. (See Figure 4-12.)
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for a summary along with a description of the shortcomings of existing flammability tests -- more systematic investigations are essential to improve fire safety relevant to space missions and to develop predictive models and new fire-resistant materials. How best to store fluids onboard spacecraft for long-duration travel, managing temperature and pressure in the presence of different thermal environments?
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influence the combustion behavior and supercritical oxidation. In fact, the lack of fundamental understanding of the dynamics and the associated chemical kinetics of supercritical oxidation limit its implementation, as critical to advance solid waste treatment and or wastewater recovery and management for long-duration spaceflights and advanced space exploration systems.
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Understanding these altered behaviors is critical to providing safe space environments and to effective processing and manufacture in space. COMPLETING THE SCIENCE IMPERATIVES It is increasingly recognized that the key scientific questions of the BPS do not stratify easily into the categories of those enabling space exploration and those enabled by having access to space.
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