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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
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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
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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
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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
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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
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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
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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
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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
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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
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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
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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
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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
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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
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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
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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
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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)
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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
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