B

Glossary and Selected Acronyms

25-OH vitamin D3 25-hydroxycholecalciferol, a metabolically active form of vitamin D
   
ACES Atomic Clock Ensemble in Space, a European space mission; advanced crew escape suit
ACME Advanced Combustion via Microgravity Experiments
ACTH adrenocorticotrophic hormone
actin protein that forms one component of the internal skeleton (cytoskeleton) of the cell
ADH antidiuretic hormone
AG artificial gravity generated by devices creating centrifugal forces
AGE arterial gas emboli
agglutinates in lunar regolith, easily crushable aggregates of smaller soil particles that have been bonded by melting during micrometeoroid impacts
AHB Animal and Human Biology (Panel)
amyloplast plant organelle that contains starch; because of its high density it moves within the cell in response to the direction of gravity
ANP atrial natriuretic peptide
applied physical sciences the study of physical sciences with particular applications in mind; in this report, the applied physical sciences of particular interest are fluid physics, combustion, and materials science
ARED advanced resistive exercise device
ATV Automated Transfer Vehicle


The National Academies | 500 Fifth St. N.W. | Washington, D.C. 20001
Copyright © National Academy of Sciences. All rights reserved.
Terms of Use and Privacy Statement



Below are the first 10 and last 10 pages of uncorrected machine-read text (when available) of this chapter, followed by the top 30 algorithmically extracted key phrases from the chapter as a whole.
Intended to provide our own search engines and external engines with highly rich, chapter-representative searchable text on the opening pages of each chapter. Because it is UNCORRECTED material, please consider the following text as a useful but insufficient proxy for the authoritative book pages.

Do not use for reproduction, copying, pasting, or reading; exclusively for search engines.

OCR for page 403
B Glossary and Selected Acronyms 25-OH vitamin D3 25-hydroxycholecalciferol, a metabolically active form of vitamin D ACES Atomic Clock Ensemble in Space, a European space mission; advanced crew escape suit ACME Advanced Combustion via Microgravity Experiments ACTH adrenocorticotrophic hormone actin protein that forms one component of the internal skeleton (cytoskeleton) of the cell ADH antidiuretic hormone AG artificial gravity generated by devices creating centrifugal forces AGE arterial gas emboli agglutinates in lunar regolith, easily crushable aggregates of smaller soil particles that have been bonded by melting during micrometeoroid impacts AHB Animal and Human Biology (Panel) amyloplast plant organelle that contains starch; because of its high density it moves within the cell in response to the direction of gravity ANP atrial natriuretic peptide applied physical the study of physical sciences with particular applications in mind; in this report, the sciences applied physical sciences of particular interest are fluid physics, combustion, and materials science ARED advanced resistive exercise device ATV Automated Transfer Vehicle 403

OCR for page 403
404 RECAPTURING A FUTURE FOR SPACE EXPLORATION auxin plant hormone thought to play a key role in regulating plant growth responses to gravity; in addition it regulates many other developmental processes in plants AVP arginine vasopressin BDCF Baseline Data Collection Facility (at NASA Kennedy Space Center) BEC Bose-Einstein condensate, at a temperature near absolute zero, atoms behave as a “superatom” biofilm complex aggregation of different microbes growing on a surface, generally living within a matrix of secreted compounds biofuel gas or liquid fuel produced from biomass, the biological materials produced by living organisms biomolecule chemical compound found in living organisms Bion Russian space capsule that can support animals (e.g., monkeys, rats) and insects in orbit for up to 3 weeks bioregenerative life life support system based on biological components designed to regenerate air and water support and produce food to sustain crew members on extended missions bisphosphonate a pharmaceutical drug to prevent bone loss BMD bone mineral density BNL Brookhaven National Laboratory boiling curve plot of heat flux versus the difference between (a) the temperature of the wall where heat is being added to a boiling liquid and (b) the temperature of the liquid Brayton cycle a thermodynamic cycle used for power generation that features high conversion efficiency and a single-phase working fluid but with the drawback of relatively low heat-rejection temperatures, requiring relatively large and massive radiators buoyant convection a form of convection in which the movement of the working fluid (gas or liquid) is caused by density differences at different points in the fluid; also referred as natural or free convection; see also forced convection CADMOS Centre d’Aide au Développement des activités en Micro-pesanteur et des Operations Spatiales (operated by CNES) carbon nanotubes hollow tubes that are made of pure carbon and are just a few nanometers in diameter CCDev Commercial Crew Development (NASA contract) CD4/CD8 subgroups of immune cells used to fight infection cellular a mode of solidification that (1) forms a fine-grained material (compared, for example, solidification to dendritic solidification) and (2) facilitates close control of the microstructures within the material, in part because the direction of growth is determined by the direction of heat flow within the material as it solidifies and not by crystallographic properties of the material

OCR for page 403
405 APPENDIX B CELSS Closed Ecological Life Support System; Controlled Environment Life Support System ceramic-matrix a composite material that uses a ceramic material (i.e., a ceramic matrix) to bind together composite the strengthening agent embedded in the matrix CHeX Confined Helium Experiment chute flow a flow of granular material down the inclined surface of a chute CIR Combustion Integrated Rack (on the ISS) closed porosity a measure of the void spaces in a material (e.g., as a percentage of the total volume of a material) that considers only those void spaces that are sealed off from the external surface of the material; total porosity is the sum of open and closed porosities closure relations small scale models that provide data on important physics phenomena that are lost when physical data or DNS results are averaged; these relations are necessary for two- fluid CMFD models to close (that is, to define all the unknowns in the model), and the accuracy of these two-fluid models is limited by the accuracy of the closure models upon which they rely CMFD computational multiphase fluid dynamics: a numerical approach using high-speed computers for evaluating the conservation equations that describe multiphase flows CNES Centre National d’Études Spatiales, the French government space agency colloid any gas, solid, or liquid in a fine state of subdivision, with particles too small to be seen in an ordinary microscope, that is dispersed in a continuous gaseous, liquid, or solid medium and either does not settle or settles very slowly combustion a technique for synthesizing materials that uses highly exothermic, self-sustaining synthesis reactions complex fluids fluids that are homogeneous at macroscopic scales but have a complex structure at microscopic scales; common examples include colloidal suspensions of solid particles in liquid (e.g., paint or ink); emulsions of two immiscible liquids such as oil and water (e.g., milk or mayonnaise); foams, which are a mixture of liquid and gas (e.g., shaving cream); and liquid crystals composite a combination of two or more materials that (1) have significantly different physical or chemical properties and (2) remain separate and distinct on a macroscopic level within the finished product; in a typical composite, one material (the matrix) is used to bind together a strengthening agent, which may take the form of filaments, foils, flakes, or other particles condensation curve plot of heat flux versus the difference between (1) the temperature of the wall where heat is being removed from a gas that is being condensed and (2) the temperature of the gas constant gravity the natural force of attraction exerted by celestial bodies, e.g., Earth stimulus convection the transfer of energy and mass in a fluid (liquid or gas) caused by the physical movement of molecules within the fluid; see also buoyant convection and forced convection countermeasure a physiological intervention to maintain normal organ and/or systemic function

OCR for page 403
406 RECAPTURING A FUTURE FOR SPACE EXPLORATION CPT symmetry the concept that the universe should behave the same if one could simultaneously reverse the charge of all particles, their “parity” or handedness, and the direction of the flow of time critical heat flux the maximum rate of heat transfer that occurs before a breakdown in the boiling process; during nucleate boiling, this occurs when the boiling process makes a transition to film boiling critical point the temperature and pressure above which the liquid and gas forms of a material no longer exist as distinct phases because the material takes the form of a supercritical fluid; the critical point for water is 705°F and 3,200 psi CTSA Clinical and Translational Science Award CVP central venous pressure cytokinin plant hormone that plays important roles in regulating development cytoskeleton internal protein skeleton of the cell; made of microtubules, microfilaments, and in animals, intermediate filaments Damec Danish Medical Centre of Research DARPA Defense Advanced Research Projects Agency DCI decompression illness (see DCS) DCS decompression sickness DDREF dose and dose rate effectiveness factor deflagration vigorous burning with subsonic flame propagation dendrite tree-like crystal that forms during solidification from a liquid Desert RATS Desert Research and Technology Studies detonation explosive combustion that spreads supersonically via shock compression diffusion flame a flame in which the oxidizer combines with the fuel (by diffusion) and burns simultaneously; in most combustion systems or fires, fuel and air are initially unmixed, resulting in the formation of diffusion flames, which typically have a distinct edge that defines the limits of the region where combustion is occurring; the alternative is premixed flames, which occur when fuel and oxidizer are mixed before they burn DLR German Aerospace Center (Deutsches Zentrum für Luft- und Raumfahrt) DNS direct numerical simulation: a simulation in computational fluid dynamics in which the Navier-Stokes equations for turbulent flows are numerically solved DOD U.S. Department of Defense DOE U.S. Department of Energy DOF degrees of freedom down mass capacity to transfer payload from a location in space, such as low Earth orbit, to Earth

OCR for page 403
407 APPENDIX B drift-flux model a computational approach for predicting the performance of a multiphase fluid that considers the performance of the fluid as a whole, rather than assessing different phases individually; although less sophisticated than CMFD models, the simplicity of drift-flux models is advantageous for engineering tasks where the sophistication of a CMFD model is not needed drop tower a facility, which may be above or below ground, in which experiments are subjected to free-fall for a few seconds to create conditions of weightlessness DTH delayed-type hypersensitivity EBV/VZV latent herpes viruses EDMP experiment data management plan EDS Emergency Detection System EELV Evolved Expendable Launch Vehicle elastic modulus the relative stiffness of a material within the elastic range, which can be calculated as the ratio of stress to strain electrolysis passing a direct electric current through an ion-containing solution to produce chemical changes at the electrodes electrometallurgical related to the use of electricity and electrolysis to extract metals from ore, regolith, or other materials EMG electromyographic activity (as measured in skeletal muscle) EMU Extravehicular Mobility Unit (space shuttle EVA suit) endodermis specialized layer of cells enclosing the transport tissues (vasculature) of the plant EP the general relativity equivalence principle that all objects, regardless of their composition, move under gravity in exactly the same way, depending only on their mass epigenetics factors modulating genetic expression without altering DNA sequences EPM European Physiology Module (of the ISS) ESA European Space Agency ETDP Exploration Technology Development Program ethylene a lightweight hydrocarbon, C2H4; ethylene is used by plants as a growth signal eukaryote a cell in which the genetic information is enclosed in a membrane-bounded structure called the nucleus; eukaryotes generally contain many other membrane-bounded regions of specialized function, called organelles EVA extravehicular activity, for example space walks performed by astronauts outside of the ISS excursion see flow excursion EXPRESS expedite the processing of experiments to space station; a standardized rack configuration used on the ISS

OCR for page 403
408 RECAPTURING A FUTURE FOR SPACE EXPLORATION extinction limit the minimum conditions necessary to sustain combustion of a flowing gas; for example, in some combustors, the extinction limit is the minimum time that a point in the flow stream (of mixed air and fuel) must spend in the combustor to sustain continuous combustion for a given set of conditions, such as fuel type, fuel/air mix, pressure, and temperature fermions a class of fundamental particles that includes systems such as the electron gas that makes metals resilient, elastic, and conductive and that is the source of forces that stabilize white dwarf stars against collapse FIR Fluids Integrated Rack (on the ISS) flammability limit the limiting conditions under which combustion of a given type can be sustained in a given environment; for example, in gas-phase combustion, flammability limits are primarily a function of the fuel type, the total pressure, the concentrations of fuel and oxygen, and the temperature; flammability limits typically describe upper and lower bounds (e.g., the maximum and minimum limits) on fuel concentration FLEX Flame Extinguishment Experiment flow excursion an event in which a two-phase system goes from one operating state to another but does not return to the original state fMRI functional magnetic resonance imaging forced convection a form of convection in which the movement of the working fluid (gas or liquid) is externally imposed, for example, by a blower or pump; see also buoyant convection free-flyer a satellite that can be used for automated microgravity research in both biological and physical sciences, such as growing bacteria in space or exposing materials to the space environment, among many other uses; mission durations, satellite bus and payload sizes, and mission purposes vary widely; free-flyers can operate either with or without human interaction and may or may not return samples or data back to Earth autonomously; some free-flyers will only transmit data back to Earth and are not designed for re-entry FSB Fundamental Space Biology (NASA program) FSL Fluid Science Laboratory (on the ISS) FSPS Fission Surface Power System (joint NASA/DOE technology effort) fuel cell device that converts chemical energy of a fuel directly into electrical energy functional residual amount of air in the lungs after exhaling capacity FY fiscal year genome the entire genetic information of an organism geomorphic relating to the surface features of a landscape and the forces that shaped them geotechnics practical application of geological science to mining, civil engineering, etc. GeV billion (giga) electron volts: unit of measure for high-energy particles

OCR for page 403
409 APPENDIX B GH growth hormone g-jitter gravity-jitter: small fluctuations in acceleration that are present in a spacecraft environment and are caused by machinery, rocket firings, astronauts in motion, etc. global equilibrium state in which intensive properties of a system are homogeneous and constant throughout the system gravitaxis the swimming of an organism in a direction determined by the gravity vector gravitropism directional growth response of plant stems and roots to the force of gravity gravity a force per unit mass experienced by a physical body as a result of mutual attraction with all other bodies, independent of electromagnetic or other forces green revolution a range of research and development advances applied to crop plants, such as reducing the height of some cereals, that greatly increased worldwide agricultural yields from the 1940s to 1970s GWAS genome-wide association study(ies) Gy gray: the SI unit of absorbed dose of ionizing radiation halon any of a group of compounds used as fire suppression agents; they are created by replacing the hydrogen atoms of a hydrocarbon with halogen atoms, such as bromine or fluorine; for example, Halon 1301, used on the space shuttle, is bromotrifluoromethane: CF3Br heat exchanger device that facilitates the transfer of heat from a hot source to a cold sink heat pipe a container of two-phase fluid used to transfer heat efficiently heat sink a reservoir to absorb thermal energy HEDS abbreviated name of the NRC report titled Microgravity Research in Support of Technologies for the Human Exploration and Development of Space and Planetary Bodies (2000) heliopause the theoretical boundary of the solar system where the Sun’s solar wind is stopped by the interstellar medium; the heliopause is at a distance of about 140 AU from the Sun Henry Gauer reflex a head-ward movement of fluid occurring during spaceflight hot pressing a process in which the particles of a powder are welded together by the simultaneous application of pressure and heat; hot pressing is also known as pressure sintering (see also sintering and liquid-phase sintering) hPa hectopascal; a unit of measure commonly used for barometric pressure; 1,013 hPa is the barometric pressure equivalent to 760 mm Hg (1 atmosphere), the nominal atmospheric pressure at Earth’s surface HRF Human Research Facility; either of two facilities, HRF-1 and HRF-2, on the ISS HTV H-II Transfer Vehicle; a Japanese launch vehicle HU hindlimb unloading [model]; a rodent model for unloading skeletal muscle in vivo in ground-based experiments

OCR for page 403
410 RECAPTURING A FUTURE FOR SPACE EXPLORATION hydrometallurgical related to the use of chemical processes involving water-based solutions to extract metals from ore, regolith, or other materials hypobaric pressure pressure less than 1 atmosphere hypoxia a condition wherein an organism receives insufficient oxygen to support its metabolism HZE particles high-energy particles such as iron nuclei present in cosmic rays; HZE particles have an energy range of about 102 to 103 MeV per nucleon ICP intracranial pressure ignition limit the minimum conditions that must be present for combustion to start in a given environment in the presence of a spark; for example, with gas phase combustion, ignition limits are primarily a function of the fuel type, the total pressure, the concentrations of fuel and oxygen, and the temperature IL interleukin IMLEO initial mass in low Earth orbit insolation the solar radiation energy received on a given surface area in a given time intensive property physical property of a system or material that does not depend on the size of the system or the amount of the material; examples include pressure, temperature, density, viscosity, and boiling point, but not mass, energy, volume, or stiffness interfacial material behaviors associated with the boundaries (faces) between different phases, phenomena including those between similar phases of different materials interstitial gas gas that may be present in the openings or pore spaces in rock or soil IOM Institute of Medicine iRED interim resistive exercise device ISLSWG International Space Life Sciences Working Group ISPR International Standard Payload Rack (on the ISS) ISRU in situ resource utilization; the proposed use of resources found or manufactured on the Moon, Mars, or other planetary bodies to further the goals of a space mission ISS International Space Station IVGEN Intravenous Fluid Generation for Exploration (project) JAXA Japan Aerospace Exploration Agency Josephson effect a phenomenon of electric current across two weakly coupled superconductors separated by a very thin insulating barrier (a Josephson junction); Josephson effects in 3He and 4He have applications in advanced technology such as new superfluid gyroscopes JSC Johnson Space Center

OCR for page 403
411 APPENDIX B laminar flame flame that occurs in an environment where fluid flow is laminar rather than turbulent (that is, the flow is smooth and orderly, with little mixing between adjacent fluid layers); laminar flames are impractical because of the low rate of mixing of fuel and air LBNP lower body negative pressure LCROSS Lunar Crater Observation and Sensing Satellite LEA launch, entry, and abort (suit) LED light-emitting diode LEO low Earth orbit; approximately 100 to 1,200 miles above Earth’s surface LET linear energy transfer; the amount of energy deposited per unit distance that a charged particle travels; high-LET radiation includes the heavier-than-protons charged-particle radiation found in galactic cosmic rays; the biological concerns are that such radiation is more damaging than is low-LET radiation such as the x-rays, gamma rays, or protons used in clinical/medical applications lignification the production of the polymer lignin in plant cell walls; leads to extremely strong support tissues within the plant liquid-phase a sintering process that occurs in the presence of a liquid that coexists with the powder sintering being sintered at the sintering temperature; the liquid phase increases the bonding rate because the capillary forces associated with the presence of the liquid are equivalent to very large external pressures (see also sintering and hot pressing) lodging the bending over of plant stems in response to extreme weather such as wind and rain; in cereal crops, lodging can lead to poor grain formation and problems with harvesting; lodged plants can often right themselves through the gravitropic response of their stems Lorentz symmetry a symmetry of physics under rotations and boosts low-shear modeled a fluid-based microbial culture environment using a rotating vessel, for which the very microgravity low shear forces generated have been shown to mimic some of the effects of microgravity LPE Lambda Point Experiment LRO Lunar Reconnaissance Orbiter LSS life support system LTMPF Low-Temperature Microgravity Physics Facility; a multiflight facility designed to attach to the Japanese Experiment Module/Exposed Facility of the ISS LVEDV left ventricular end diastolic volume MARES Muscle Atrophy Research and Exercise System (on the ISS) MASER Material Science Experiment Rocket MDCA Multi-user Droplet Combustion Assembly MEDES Institute for Space Medicine and Physiology, Toulouse, France MELFI Minus Eighty Degree Laboratory Freezer for the ISS

OCR for page 403
412 RECAPTURING A FUTURE FOR SPACE EXPLORATION MELiSSA Micro-Ecological Life Support System Alternative; a project from a consortium of European and Canadian research laboratories and universities that is managed by the European Space Agency; investigates artificial microbe/plant ecosystems with an aim to develop elements of a bioregenerative life support system mesoscale of intermediate size; in materials science, of a size ranging from approximately 10 microns to 1 millimeter metabolomics an analytical technique that comprehensively catalogs the small-molecule metabolites present in an organism metagenomics the study of the multiple genomes found in environmental samples metal-ceramic a composite with both metal and ceramic components, such as ceramic particles dispersed composite in a metal matrix or metal filaments embedded in a ceramic matrix; see also composite metal-matrix a composite material that uses a metallic substance (i.e., a metal matrix) to bind together composite the strengthening agent embedded in the matrix; see also, composite MHC myosin heavy chain; the motor protein regulating muscle contraction MHD magnetohydrodynamics microarray an analytical technique by which the levels of expression of thousands of genes can be assayed simultaneously microgravity an environment in which there is very little net gravitational force, such as in free-fall or in orbit MICROSCOPE a room-temperature weak equivalence principle experiment in space relying on electrostatic differential accelerometers MISSE Materials International Space Station Experiment mixed fields mixtures of protons with heavier charged particles or of a variety of heavy particles model system an organism that is particularly tractable to study and for which there is a large body of information about its development and response systems, and that is used to infer how other similar biological systems may respond or develop; examples: for bacteria, Escherichia coli; for animals, the nematode Caenorhabditis elegans and the fruit fly Drosophila melanogaster; and for plants, thale cress (Arabidopsis thaliana) and rice (Oryza sativa) motor unit a group of muscle fibers of similar properties innervated by a common neuron MPLM Multi-Purpose Logistics Module (on the ISS) MRM1 Mini-Research Module-1 (on the ISS) MSG Microgravity Science Glovebox (on the ISS) MSL Materials Science Laboratory (on the ISS) MSL-1 Microgravity Science Lab (space shuttle mission) MSNA muscle sympathetic nerve activity MSRR-1 Materials Science Research Rack-1

OCR for page 403
413 APPENDIX B multiphase any process involving a mixture of two or more phases (solid, liquid, and gas); a glass of ice water is a multiphase system myostatin an antigrowth factor protein that impacts bone and muscle formation nanoslurry a mixture of nanoscale particles and a liquid NASA National Aeronautics and Space Administration Navier-Stokes the equations of motion for a viscous fluid in terms of pressure, density, external force, equations fluid velocity, and viscosity NE norepinephrine NEP nuclear electric propulsion NGF nerve growth factor NIAID National Institute of Allergy and Infectious Diseases NIH National Institutes of Health Nomex® an artificial heat- and fire-resistant fabric manufactured by the DuPont Corporation NRC National Research Council NSBRI National Space Biomedical Research Institute NSF National Science Foundation NSRL NASA Space Radiation Laboratory at Brookhaven National Laboratory; a facility able to generate the spectrum of radiation types to which astronauts are likely to be exposed in space NTR nuclear thermal rocket nucleate boiling in pool boiling, the boiling that occurs when individual bubbles of gas appear on the heat transfer surface (that is heating the fluid) and then rise to the surface, as opposed to film boiling, which occurs when the bubbles of gas are formed so rapidly that they combine to form a gas film that covers the heat transfer surface open porosity a measure of the void spaces in a material (e.g., as a percentage of the total volume of a material) that considers only those void spaces that are connected to the external surface of the material; total porosity is the sum of open and closed porosities order parameter a parameter of a system that is zero in the disordered phase, exhibits large fluctuations about its zero mean as the critical point is approached, and grows from zero to larger values as the ordered phase is entered organelle a membrane-bounded structure that is found within a cell and is a site of specialized function orthostatic inability to maintain normal blood pressure while standing intolerance osmotic force the driving force of water movement across the membrane of a cell

OCR for page 403
414 RECAPTURING A FUTURE FOR SPACE EXPLORATION Ostwald ripening tendency for a particle dispersion to grow in diameter over time as smaller particles (with higher solubility) dissolve preferentially, with subsequent crystallization onto larger particles, making them even larger PCAI power, communications, avionics, and informatics PHA polyhydroxyalkanoate phase a homogeneous and physically distinct state of aggregation of a substance, e.g., solid, liquid, or vapor phase phase separation separation of a mixture of phases into individual component phases physically based a model of system behavior based on fundamental physical principles (e.g., model thermodynamic laws) and the appropriate physical mechanisms (e.g., heat transfer, capillary flow), as opposed to an empirical model, which is based primarily on experimental measurements and incorporates only a limited theoretical understanding of the system pile flow a flow of granular material along the inclined surface of a stationary pile corresponds to energies of ~1019 GeV Planck scale PLSS portable life support system pO2 (or PO2) partial pressure of oxygen pool boiling boiling that occurs when the heating surface is submerged in a relatively large body of still liquid (there is no liquid movement except that which arises naturally from buoyant convection currents and from agitation by bubbles of gas that form during the boiling process) PRA plasma renin activity protein balance the net status of protein content in a muscle fiber; if the protein balance is negative, the fiber atrophies protein turnover the process in a cell by which any given protein stock undergoes simultaneous processes of synthesis and degradation proteomics an analytical approach for the large-scale identification of the proteins present within an organism; can be used to monitor how the spectrum of proteins changes with environmental changes psi pounds per square inch PTSD post-traumatic stress disorder pyrolysis decomposition of a material or compound due to heating without combustion, which is prevented by the absence of oxygen or any other oxidizing reagents pyrometallurgical related to the use of heat-based processes, such as smelting, to extract metals from ore, regolith, or other materials QT interval in cardiology, a measure of time that represents the interval between electrical depolarization and repolarization of the left and right ventricles of the heart

OCR for page 403
415 APPENDIX B quantum gas a system of particles in which the size of an individual particle’s quantum wavelength becomes large compared to the length scale of interactions between the particles in the system quantum phase transition from a continuous quantum fluid to a discrete atomic lattice, such as the transition “superfluid-to-Mott” insulator transition quorum sensing the coordination of responses from bacterial populations through the exchange of small signaling molecules; quorum sensing allows bacteria to respond to their own population levels R&D research and development radiation anything propagated as rays, waves, or a stream of particles, but especially light and other electromagnetic waves or the emission from radioactive substances radioisotope a radioactive isotope of an element Rankine cycle a thermodynamic cycle for power generation that uses separate boilers and condensers with two-phase (liquid/vapor) mixtures with high conversion efficiencies and high heat- rejection temperatures, allowing reduced radiator mass and areas RANKL an orthoclase-stimulating peptide that induces bone loss RE resistance exercise reaction wood strengthening tissue that forms upon mechanical stress of woody plants, such as occurs from wind, snow build up, or the weight of the plant reactive hot a hot pressing process in which powders are mixed and an exothermic chemical reaction pressing occurs reactive oxygen highly reactive molecules derived from oxygen, such as superoxide or hydrogen species peroxide; reactive oxygen species are produced during normal metabolism, but they can be deleterious to the cell; they are also widely used as signaling molecules that regulate organism function reduced gravity gravity levels less than 1 g REM rapid eye movement residence time the length of time that combustion gases are in the combuster; it is larger for larger combusters and shorter for systems with higher gas velocities resorption the process of losing bone material RFC regenerative fuel cell regolith surface rock, especially used to describe the lunar surface soil rheology the science of the deformation and flow of liquids and solids rpm revolutions per minute RPS radioisotope power system RVLM rostral ventrolateral medulla; a brain region

OCR for page 403
416 RECAPTURING A FUTURE FOR SPACE EXPLORATION SACHRP Secretary’s Advisory Committee on Human Research Protections (of the U.S. Department of Health and Human Services) SARG Suborbital Applications Researchers Group sclerostin a bone factor gene stimulating bone growth self-healing polymer composite designed to automatically repair cracks within the material that may material be caused by impact, fatigue, or wear SEP solar electric propulsion SHS self-propagating high-temperature synthesis: see combustion synthesis sintering a process in which the particles of a packed powder are bonded to each other by heating to a high temperature below the melting temperature (but generally above one-half the absolute melting temperature); this process generally takes place without external pressure (see also hot pressing and liquid-phase sintering) SLS Space Life Sciences (as referred to in STS space shuttle science missions, e.g., SLS-1) solar particle event flux of energetic ions and/or electrons of solar origin sounding rocket uncrewed rocket used for short, non-orbital flights; the most common uses are to study Earth’s atmosphere and to conduct microgravity research Spacelab Spacelab was a reusable laboratory module flown in the space shuttle’s cargo bay and used for microgravity experiments that were operated and/or monitored by astronauts. Spacelab had four main components: a pressurized laboratory module with a shirt-sleeve working environment; a tunnel for gaining access to the module; one or more pallets for exposing materials and equipment to space; and an instrument pointing system for astronomical, solar, and/or Earth observations, along with other targets. A memorandum of understanding was signed in 1973 between the European Space Agency (then the European Space Research Organization) and NASA (with Marshall Space Flight Center as the lead NASA center) to design and develop the laboratory. The 10-foot-long pressurized modules were built by an industrial consortium and flew on all five space shuttle vehicles between 1983 and 1998. SpaceX Space Exploration Technologies Corporation specific impulse efficiency of rocket engines expressed as thrust per unit mass of flow rate produced by burning rocket propellant spinodal a mechanism by which a solution of two or more components can separate into distinct decomposition regions (or phases) with distinctly different chemical compositions and physical properties STAR Space-Time Asymmetry Research (project) Starling Landis an equation designed to estimate pressures in the capillary beds of the circulatory system equation STEP Satellite Test of Equivalence Principle; a space mission to test the weak equivalence principle using cryogenically controlled test masses on a spacecraft orbiting Earth

OCR for page 403
417 APPENDIX B Stirling cycle a method of power conversion that utilizes sealed gas/piston-linear alternator components and can operate at relatively high efficiency with comparatively small heat source-sink differential temperatures stoichiometric mix a “perfect” mix of a combustible gas and air, such that there is just enough oxygen to support combustion of all the fuel present stoichiometry the proportions in which chemical elements combine or are produced and the weight relations in a chemical reaction, such as combustion strain deformation of a body in response to an external force stress external force per unit area acting on a body STS Space Transport System; formal name for the U.S. space shuttles; used with a number to designate a specific space shuttle flight, e.g., STS-17 superfluid a fluid, such as a liquid form of helium, exhibiting a frictionless flow at temperatures close to absolute zero surface engineered advanced coating consisting of multiple, thin layers designed to improve the performance coating of a given component in a particular application by improving the mechanical, physical, and/or chemical properties of that component surface spreading the phenomenon observed when a relatively insoluble liquid is placed on the clean surface of another liquid (or when a liquid is placed on the smooth surface of a solid) surfactant surface-active agent; also known as a wetting agent, a surfactant lowers the surface tension of a liquid, allowing easier spreading SWAB Surface, Water, and Air Biocharacterization (program); an environmental sampling program established by NASA to document the microbes found in the water and air supply and on the surfaces of the ISS T3 triiodothyronine (the active form of thyroid hormone) T4 thyroxine tensegrity a structure in which compression and tension forces are balanced throughout a network; in a cell, tensegrity is thought to reside in the rigid and flexible components of the cytoskeleton that are connected together and so can rapidly transmit mechanical forces throughout this network thermal wadi an engineered source of stored solar energy using modified lunar regolith as a thermal storage mass thermophotovoltaic the selective emission and conversion to electrical energy of thermally produced photons thermophysical related to physical properties that are affected by temperature TKSC [JAXA] Tsukuba Space Center; located in Tsukuba, Japan TNF-α tumor necrosis factor-alpha; a cytokine that induces inflammatory responses transcriptional the use of approaches such as microarray analysis to catalog the expression/activity of a profiling wide range of genes in an organism

OCR for page 403
418 RECAPTURING A FUTURE FOR SPACE EXPLORATION transcriptome the spectrum of genes that are being actively expressed at any moment in time; the transcriptome can change as an organism experiences new stimuli and changes the genes it is expressing in response to those stimuli tree of life a depiction of the interrelatedness of the various kingdoms of life as branches on a tree, with the trunk reflecting their common ancestry; DNA sequencing has been used in recent years to more closely define these relationships and so locate organisms more precisely within this tree representation of ancestry TRL technology readiness level; one of a set of nine graded definitions/descriptions (TRL-1 to TRL-9) of stages of technology maturity; for example TRL-1 indicates that a basic principle has been observed and reported, TRL-8 indicates a design qualified for spaceflight TSH thyroid stimulating hormone tubulin a protein that forms one component of the internal skeleton, the cytoskeleton, of cells tumbler flow a flow of granular material in a rotating drum turbulent flame flame that occurs in an environment where fluid flow is turbulent rather than laminar (that is, the flow is chaotic and disorganized, with substantial mixing between adjacent fluid layers); all practical combustion systems with liquid or gas fuels use turbulent flow to provide adequate mixing of fuel and air twisted ribbons twisted metal strips placed in the water-filled tubes of a boiler to increase the boiling rate by providing additional nucleation sites for the formation of gas bubbles unitized RFC a regenerative fuel cell with a particular packing geometry up-mass capacity to transfer payload from Earth to a location in space, such as low Earth orbit USOC user support and operation center (ESA centers) UV ultraviolet, a portion of the electromagnetic spectrum Van der Waals a group of relatively weak and temporary intermolecular interactions that generally result forces when a molecule or group of molecules become polarized into a magnetic dipole, most often because of uneven or shifting distributions within the electron clouds of the atoms vasculature (plant) specialized tissue that transports water, mineral nutrients, and sugars produced by photosynthesis around the plant; consists of two specialized cell types: xylem that principally transports water and phloem, which is largely responsible for the movements of sugars VGE venous gas emboli wetting the ability of a liquid to maintain contact with a solid surface; the degree of wetting is determined by a force balance between adhesive and cohesive forces WORF Window Observational Research Facility (on the ISS)

OCR for page 403
419 APPENDIX B ZARM Zentrum für angewandte Raumfahrttechnologie und Mikrogravitation in Bremen, Germany zero gravity an environment in which the net vector of all gravitational and accelerative forces acting on a body is essentially zero; see microgravity

OCR for page 403