Recapturing a Future for Space Exploration Life and Physical Sciences Research for a New Era (2011) / Chapter Skim
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4 Plant and Microbial Biology
4 Plant and Microbial Biology
Pages 57-80
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From page 57... ...
The reduced gravity of spaceflight is therefore outside the limits that have shaped terrestrial biology. This fact provides the overarching principle for the need to understand the biological impacts of spaceflight environments.
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From page 58... ...
For example, an improved understanding of how to optimize plant growth in the extreme environment of spaceflight may lead to strategies to increase the efficiency of terrestrial crop production, and insights into how microbial populations change in response to the stresses of spaceflight could provide clues to how microbial populations might be managed in terrestrial settings. RESEARCH ISSUES Overview: The Need for Modern Analyses Applied to Model Systems The past decade has redefined our understanding of biology in terrestrial settings at the molecular, develop mental, and cellular levels.
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From page 59... ...
A NASA research thrust into these fundamental control mechanisms underlying plant growth and development would provide knowledge needed to design plant-based systems as an integral component of bioregenerative life support systems for extended human spaceflight, as well as provide a better understanding of plant growth control mechanisms on Earth. The mechanisms underlying the control of subsequent plant growth responses have received intensive study, with directional transport of the plant hormone auxin emerging as a significant regulatory element.
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From page 60... ...
-- for example, those involved in a bioregenerative life support system -- so they can better handle the environments involved in space exploration. There has been an ongoing interest in the responses of bacteria to the spaceflight environment, 26 and these studies indicate that when grown in a liquid environment in microgravity, bacteria behave differently than when grown in the same environment under normal gravity.
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From page 61... ...
61 PLANT AND MICROBIAL BIOLOGY FIGURE 4.1 Microbial contaminants growing on the interior wall of the International Space Station where crew placed their clothing after working out. The panel eventually had to be replaced after attempts at decontamination failed.
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From page 62... ...
Here again the observations reinforce the need to develop a research portfolio aimed at searching across kingdoms for commonalities and differences in the themes of sensing and response. Finally, bacteria have intercellular communication systems that work through molecules known as quorum sensing signals.40,41 We have no idea how these signals may function in spaceflight environments.
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From page 63... ...
. Both HZE particles and protons can be produced at the NSRL to perform focused, mechanistic studies on the biological consequences of exposure to the components of space radiation environments.
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From page 64... ...
In addition to considerations relative to plants and microbes within human spaceflight environments, a pri mary and long-term goal of sustaining life in remote space locations such as the Moon or Mars is to minimize the overall cost by employing bioregenerative life support systems. Because plants tolerate pressures much lower than those required for humans, well below 25 kPa depending on the plant and its stage of growth, 50,51 plants could be grown within low-pressure habitats, thereby saving on the resources needed to maintain high atmospheric pressures.
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From page 65... ...
can be grown successfully in space and advances in understanding how plants respond to their environment. The improvements in hardware for plant growth in space suggest that future experiments will need to address fewer of the syndrome components due to intrinsic factors such as hardware limitations and can instead focus on fundamental extrinsic factors such as microgravity and partial gravity or radiation exposure during both spaceflight and excursions to planetary surfaces such as the Moon and Mars.
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From page 66... ...
The ISS provides a limited platform to understand the relationship of microgravity and other aspects of space and spaceflight environments to bacterial virulence. Currently, bacterial virulence is assayed post-flight in groundbased facilities.
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From page 67... ...
It will be critical to determine whether changes in microbial populations and plant pathogenicity are a response to the unique elements of the spaceflight environment, such as direct effects of microgravity on microbial or plant physiology, or are effects that relate to suboptimal growth conditions such as poor humidity control or nutrient delivery in plant growth chambers designed for use in space. Such studies may not only have long-term benefits for life support systems in low-gravity environments; an increase in our understanding of how to optimize plant growth conditions/responses in the controlled environments of spaceflight may also benefit crop production in controlled environments on Earth.
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From page 68... ...
Early studies focused on wheat, potato, soybean, and lettuce as model CELSS candidate crop species.101-104 The common outcome of these studies was yield rates exceeding world records for those crops in the field.105,106 Calculations indicated that caloric and nutritional requirements for a space-crew diet could be met by ≤50 m2 of crop-growth space per person, with air revitalization occurring by default.107,108 The subsequent Advanced Life-Support Program supported research on resource recovery, systems analysis, food technology, and some plant research during the 1990s.109-114 Several multi-institutional NASA Specialized Centers of Research and Training (NSCORTs) were established in the 1990s and early 2000s to address systems integration issues for closing loops between edible-biomass production, food processing, human activities, and resource recovery in a complex life support system that would be closed with respect to mass but open with respect to energy.115,116 Hypobaric pressure was also evaluated to reduce the structural mass required for growing plants in space.117 Physico-chemical resource recovery was added to bioregenerative approaches.
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From page 69... ...
Ground-based analysis of shared specimens and data from space experiments using new technological approaches such as transcript profiling would increase the value of research and build a broad community of researchers engaged in solving the central issues of space biology. In addition, ground-based facilities that would allow systems integration and validation for a bioregenerative life support system will need to be implemented, with the goal of testing such integration toward the end of the next 10 years, once the applicability of individual components has been rigorously verified.
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From page 70... ...
ity and serve as a preparatory step to interplanetary journeys. The upcoming completion of the ISS is leading to a new era in which operations can focus on research and the development and validation of technologies to enable space exploration.
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From page 71... ...
The effects of the spaceflight environment on microbial population dynamics are largely unknown and represent both a significant gap in our knowledge and an important opportunity to study the evolution of microbial populations and predict health and engineering risks during long-term space exploration. As part of this effort, NASA should: a.
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From page 72... ...
Establish a robust spaceflight program of research analyzing plant and microbial growth and physiologi cal responses to the multiple stimuli encountered in spaceflight environments; b. Encourage research studying the responses to individual components of spaceflight environments, such as altered gravity, radiation, and atmospheric composition, and to the integrated effects of these multiple fac tors; and c.
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From page 73... ...
Stable funding of multiyear durations is essential for implementing projects that will enable a scientific community that is not only immediately responsive to short-term issues but also capable of educating the next generations of space biology scientists. The space biology research programs will advance rapidly when supported by a robust ground research pro gram.
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From page 74... ...
74 RECAPTURING A FUTURE FOR SPACE EXPLORATION TABLE 4.1 Overview of Research Timeline Research Targets Current Status 2010-2020 2020 and Beyond Outcomes Understand the SWAB program • Establish Microbial Increased effects of space samples ISS Observatory on the ISS to understanding of environments populations, little study population dynamics the fundamental on microbial experimentation and genomic alterations mechanisms and populations • Generational experiments designs of life on and metagenomics to Earth investigate microbial evolution in space Ability to predict the adaptation Determine Impacts documented, • Carry out controlled • Apply systems-level processes of cell, how space but mechanisms comprehensive analysis analyses to responses to microorganisms, environments poorly characterized with model systems multiple stimuli plants, and affect organisms and understood • Focus rigorous, highly ecosystems in replicated "omic"a at critical stages Components of response to space of growth and spaceflight analyses on mechanistic environments development syndrome not questions using a single clearly separated stimulus Understand No consensus on • Resolve basis of cell and • Test interactions with gravity sensing gravity sensing in microbial responses to other stimuli and response microbes microgravity • Systems analysis systems Components identified • Define and test establishing interactions in plants, but molecular basis using of gravity responses with little systems spaceflight experiments other stimuli understanding in combination with centrifugation Mitigate and Indications of altered • Characterize and • Develop and evaluate Risks to the manage human virulence of assess critical risks by candidate countermeasures exploration infectious disease single species of assessing effects of with ground analogs and process decreased risks microorganisms space environments on spaceflight by a mechanistic in spaceflight pathogenic and cooperative appreciation of the conditions interactions among species effects of radiation, • Advance understanding of gravity, and closed mechanisms environments on plant and microbe Reduce ISS baseline is 90-day • Identify critical • Integrated testing of lower systems, and on exploration resupply components for rigorous equivalent system mass human health and costs and risks Low-level effort in ground-based programs life support technologies performance through robust, United States after • Emphasis on fresh food and subsystems in relevant sustainable, five decades of first environments bioregenerative research • Trade studies for low Earth • Select space-optimized life support International efforts orbit, the Moon, Mars plants and microbes components strong • On-orbit/lunar surface validation Reduce Little information about • Expand knowledge of • Establish acceptable levels uncertainties the impacts of space risk using comprehensive of risk about the risks of radiation on plants analyses of model systems • Develop and test space radiation and microbes in ground facilities, countermeasures including environments especially the NASA Space genetic resistance to microbes and Radiation Laboratory plants • Validation in the combined space environment using free-flyers and external platforms on the ISS
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From page 75... ...
Space biology represents a potential opportunity for coalescing disparate programmatic elements within NASA and its international partners. Biological studies discussed in this report currently have representation in multiple parts of NASA, including astrobiology, planetary protection, fundamental space biology, and exploration life sci ences.
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From page 76... ...
Gravitational and Space Biology Bulletin 18(2)
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From page 77... ...
2008. Managing Space Radiation Risk in the New Era of Space Exploration.
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From page 78... ...
1998. A Strategy for Research in Space Biology and Medicine in the New Century.
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From page 79... ...
Gravitational and Space Biology Bulletin 14(2)
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From page 80... ...
1998. A Strategy for Research in Space Biology and Medicine in the New Century.
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