Recapturing a Future for Space Exploration: Life and Physical Sciences Research for a New Era (2011)
Chapter: Appendix B: Glossary and Selected Acronyms
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Suggested Citation:
"Appendix B: Glossary and Selected Acronyms." National Research Council. 2011. Recapturing a Future for Space Exploration: Life and Physical Sciences Research for a New Era. Washington, DC: The National Academies Press.
doi: 10.17226/13048.
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 |
Suggested Citation:
"Appendix B: Glossary and Selected Acronyms." National Research Council. 2011. Recapturing a Future for Space Exploration: Life and Physical Sciences Research for a New Era. Washington, DC: The National Academies Press.
doi: 10.17226/13048.
| 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 support | life support system based on biological components designed to regenerate air and water 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 solidification | a mode of solidification that (1) forms a fine-grained material (compared, for example, 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 |
Suggested Citation:
"Appendix B: Glossary and Selected Acronyms." National Research Council. 2011. Recapturing a Future for Space Exploration: Life and Physical Sciences Research for a New Era. Washington, DC: The National Academies Press.
doi: 10.17226/13048.
| CELSS | Closed Ecological Life Support System; Controlled Environment Life Support System |
| ceramic-matrix composite | a composite material that uses a ceramic material (i.e., a ceramic matrix) to bind together 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 synthesis | a technique for synthesizing materials that uses highly exothermic, self-sustaining 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 stimulus | the natural force of attraction exerted by celestial bodies, e.g., Earth |
| 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 |
Suggested Citation:
"Appendix B: Glossary and Selected Acronyms." National Research Council. 2011. Recapturing a Future for Space Exploration: Life and Physical Sciences Research for a New Era. Washington, DC: The National Academies Press.
doi: 10.17226/13048.
| 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 |
Suggested Citation:
"Appendix B: Glossary and Selected Acronyms." National Research Council. 2011. Recapturing a Future for Space Exploration: Life and Physical Sciences Research for a New Era. Washington, DC: The National Academies Press.
doi: 10.17226/13048.
| 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 |
Suggested Citation:
"Appendix B: Glossary and Selected Acronyms." National Research Council. 2011. Recapturing a Future for Space Exploration: Life and Physical Sciences Research for a New Era. Washington, DC: The National Academies Press.
doi: 10.17226/13048.
| 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 capacity | amount of air in the lungs after exhaling |
| 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 |
Suggested Citation:
"Appendix B: Glossary and Selected Acronyms." National Research Council. 2011. Recapturing a Future for Space Exploration: Life and Physical Sciences Research for a New Era. Washington, DC: The National Academies Press.
doi: 10.17226/13048.
| 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 |
Suggested Citation:
"Appendix B: Glossary and Selected Acronyms." National Research Council. 2011. Recapturing a Future for Space Exploration: Life and Physical Sciences Research for a New Era. Washington, DC: The National Academies Press.
doi: 10.17226/13048.
| 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 phenomena | material behaviors associated with the boundaries (faces) between different phases, 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 |
Suggested Citation:
"Appendix B: Glossary and Selected Acronyms." National Research Council. 2011. Recapturing a Future for Space Exploration: Life and Physical Sciences Research for a New Era. Washington, DC: The National Academies Press.
doi: 10.17226/13048.
| 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 sintering | a sintering process that occurs in the presence of a liquid that coexists with the powder 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 microgravity | a fluid-based microbial culture environment using a rotating vessel, for which the very 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 |
Suggested Citation:
"Appendix B: Glossary and Selected Acronyms." National Research Council. 2011. Recapturing a Future for Space Exploration: Life and Physical Sciences Research for a New Era. Washington, DC: The National Academies Press.
doi: 10.17226/13048.
| 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 composite | a composite with both metal and ceramic components, such as ceramic particles dispersed in a metal matrix or metal filaments embedded in a ceramic matrix; see also composite |
| metal-matrix composite | a composite material that uses a metallic substance (i.e., a metal matrix) to bind together 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 |
Suggested Citation:
"Appendix B: Glossary and Selected Acronyms." National Research Council. 2011. Recapturing a Future for Space Exploration: Life and Physical Sciences Research for a New Era. Washington, DC: The National Academies Press.
doi: 10.17226/13048.
| 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 equations | the equations of motion for a viscous fluid in terms of pressure, density, external force, 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 intolerance | inability to maintain normal blood pressure while standing |
| osmotic force | the driving force of water movement across the membrane of a cell |
Suggested Citation:
"Appendix B: Glossary and Selected Acronyms." National Research Council. 2011. Recapturing a Future for Space Exploration: Life and Physical Sciences Research for a New Era. Washington, DC: The National Academies Press.
doi: 10.17226/13048.
| 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 model | a model of system behavior based on fundamental physical principles (e.g., 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 |
| Planck scale | corresponds to energies of ~1019 GeV |
| 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 |
Suggested Citation:
"Appendix B: Glossary and Selected Acronyms." National Research Council. 2011. Recapturing a Future for Space Exploration: Life and Physical Sciences Research for a New Era. Washington, DC: The National Academies Press.
doi: 10.17226/13048.
| 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 | transition from a continuous quantum fluid to a discrete atomic lattice, such as the “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 pressing | a hot pressing process in which powders are mixed and an exothermic chemical reaction occurs |
| reactive oxygen species | highly reactive molecules derived from oxygen, such as superoxide or hydrogen 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 |
Suggested Citation:
"Appendix B: Glossary and Selected Acronyms." National Research Council. 2011. Recapturing a Future for Space Exploration: Life and Physical Sciences Research for a New Era. Washington, DC: The National Academies Press.
doi: 10.17226/13048.
| 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 material | polymer composite designed to automatically repair cracks within the material that may 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 decomposition | a mechanism by which a solution of two or more components can separate into distinct regions (or phases) with distinctly different chemical compositions and physical properties |
| STAR | Space-Time Asymmetry Research (project) |
| Starling Landis equation | an equation designed to estimate pressures in the capillary beds of the circulatory system |
| 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 |
Suggested Citation:
"Appendix B: Glossary and Selected Acronyms." National Research Council. 2011. Recapturing a Future for Space Exploration: Life and Physical Sciences Research for a New Era. Washington, DC: The National Academies Press.
doi: 10.17226/13048.
| 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 coating | advanced coating consisting of multiple, thin layers designed to improve the performance 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 profiling | the use of approaches such as microarray analysis to catalog the expression/activity of a wide range of genes in an organism |
Suggested Citation:
"Appendix B: Glossary and Selected Acronyms." National Research Council. 2011. Recapturing a Future for Space Exploration: Life and Physical Sciences Research for a New Era. Washington, DC: The National Academies Press.
doi: 10.17226/13048.
| 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 forces | a group of relatively weak and temporary intermolecular interactions that generally result 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) |
Suggested Citation:
"Appendix B: Glossary and Selected Acronyms." National Research Council. 2011. Recapturing a Future for Space Exploration: Life and Physical Sciences Research for a New Era. Washington, DC: The National Academies Press.
doi: 10.17226/13048.
| 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 |
Suggested Citation:
"Appendix B: Glossary and Selected Acronyms." National Research Council. 2011. Recapturing a Future for Space Exploration: Life and Physical Sciences Research for a New Era. Washington, DC: The National Academies Press.
doi: 10.17226/13048.
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