NASA Thesaurus - Volume 3 - Definitions

8/14/2019 NASA Thesaurus - Volume 3 - Definitions

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NASA SP-7064(VOI . 3)

NASATHESAURUSVOLUME 3DEFINITIONS1988 EDITION

National Aeronauticsand Space Adm inistrationScientific and TechnicalInformation Division

1988


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ISSN 0899-5257

This document is available from the National Technical Information Service (NTIS), Springfield,Virgin ia 22161 for


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TABLE OF CONTENTS

Volume 1 Hierarchical ListingVolume 2 Access VocabularyVolume 3 DefinitionsIntroduction ............................................................................................... vSources of Definitions ............................................................................... vTypical Definition Entry ............................................................................. vDefinitions ................................................................................................. 1

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INTRODUCTIONDefinitions are given for m ost terms a dded to the NASA Thesaurus since 197 6 as well as for manyearlier terms. De finitions of mo re comm on or general scientific terms are given a NASA slant if on eexists. Certain terms are not defined as a matter of policy: common place names, chemical ele-ments, specific models of comp uters, and non technical terms. Other terms lack definitions becausethe NASA Thesaurus predates by a number of years the systematic effort to define terms. N everthe-less, definitions of older terms are continually being added.The following da ta are provide d for each definition: term in up percase/lowercase form, definitionper se, source, and year the term (not the definition) was adde d to the NASA Thesaurus.The NASAHistory Office is the authority for capitalization of NASA names. USE cross references from theNASA Thesaurus are also included in uppercase/lowercase form.SOURCES OF DEFINITIONSDefinitions with no source given were constructed by lexicographers at the NASA Scientific andTechnical Information (ST I) Facility, who rely on the following sources for their information: expertsin the field, literature searches from the NASA STI database, and specialized references, includingthose listed below.

ASTM. Compilation of ASTM Standard Definitions,6th edition. Ph iladelphia, PA, ASTM, 1986.Copyright, the American Society for Testing and Materials (ASTM). All rights reserved. Usedwith the permission of ASTM. Two ASTM sou rces are distinguished: stan dards are iden tified byan alphanume ric designation with no hyphen; committees are identified by a n alphanumericdesignation with a hyphen. The original definitions appeared in the Annual Book of ASTMStandards.DOE. Energy Data Base Subject Thesaurus (DOE/TIC-7000-R7). Oak Ridge, TN, Departmentof Energy, 1987.SP-7. Dictionary of Technical Terms for Aerospace Use, NASA SP -7. Washington, DC, NASA,1965.In some cases, definitions used from these sources have been subjected to editorial alterations,such as making a definition agree in number with the NASA form of the term.

TYPICAL TERM DEFINITION ENTRY

TERM -prisms Transparent bodies with at least two polished plane faces inclinedwith respect to each other, from which light is reflected or through/ hich ,light, s refracted. When light is refracted by a prism whoserefractive index exceeds that of the surrounding medium, it isdeviated or bent toward the thicker part of the prism.DEFINITION ASTM (E 175,E-25) 1968 YEAR TERM ENTEREDSOURCE OFDEFINITION


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NASA THESAURUSVOLUME 3DEFINITIONS

AaberrationIn astronomy, the apparent angular displacement of the positionof a celestial body in the direction of motion of the observer,caused by the combination of the velocity of the observer andthe velocity of light. In optics, a specific deviation from perfectimagery, as, for example: spherical aberration, coma, astigmatism,curvature of field, and distortion. SP-7 1968ablated nosetipsUse PANT programablationThe removal of surface material from a body by vaporization,melting, chipping, or other erosive process; specifically theintentional removal of material from a nose cone or spacecraftduring high speed movement through a planetary atmosphere toprovide thermal protection to the underlying structure. SP-7 1968ablative materialsMaterials, especially coating materials, designed to provide thermalprotection to a body in a fluid stream through the loss of mass.

SP-7 1968abrasionThe surface loss of a material due to frictional forces.

ASTM (01566,0- 1) 1968abrasivesRocks, minerals, or other substances that, owing to their superiorhardness, toughness, consistency, of other properties, are suitablefor grinding, cutting, polishing, scouring, or similar use.

ASTM (0 53, D- 18) 1968absolute zeroTemperature of -273.16 deg. C or -459.69 deg. F or 0 deg. K atwhich molecular motion vanishes and a body has no heat energy.

1980absorptanceThe ratio of the radiant flux absorbed by a body to that incidentupon it. SP-7 1968absorptionThe process by which radiant energy is absorbed and convertedinto other forms of energy. In general, the taking up or assimilationof one substance by another. In vacuum technology gas enteringthe interior of a solid. SP-7 1968absorption bandsUse absorption spectraabsorption coefficientUse absorptivity

absorption coolingRefrigeration in which cooling is effected by the expansion ofliquid ammonia into gas and the absorption of the gas by water.The ammonia is reused after the water evaporates. 1980absorption cross sectionsIn radar, cross sections characterized by the amount of powerremoved from a beam by absorption of radio energy by a targetto the power in the beam incident upon the target. Used forcapture cross sections. SP-7 1968absorption spectraThe arrays of absorption lines and absorption bands which resultfrom the passage of radiant energy from a continuous sourcethrough a selectively absorbing medium cooler than the source.Used for absorption bands and spectral absorption. SP-7 1968absorptive indexUse absorptivityabsorptivityThe capacity of a material to absorb incident radiant energy,measured as the absorptance of a specimen of material thickenough to be completely opaque, and having an optically smoothsurface. Used for absorption coefficient and absorptive index.

SP-7 1968accelerated life testsMethods designed to approximate, in a short time, the deterioratingeffects under normal long-term service conditions.

ASTM (D 1566,D-11) 969acceleration (physics)The rate of change of velocity. The act or process of acceleratingor the state of being accelerated. Used for boost and G force.

SP-7 1968acceleratorsMachines that ionize gases and electrically accelerate the ionsonto targets. ASTM (E 385, E-10) 1968accelerometersTransducers which measure acceleration or gravitational forcescapable of imparting acceleration. SP-7 1968access controlThe procedures for providing systematic, unambiguous, orderly,reliable and generally automatic use of communication lines,channels, and networks for information transfer. 1980acclimatizationThe adjustments of a human body or other organism to a newenvironment; the bodily changes which tend to increase efficiencyand reduce energy loss. Used for deacclimatization. SP-i 1968

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ACCOMMODATION COEFFICIENT

accommodation coefficientThe ratio of the average energy actually transferred between asurface and impinging gas molecules which are scattered by thesurface to the average energy which would theoretically betransferred if the impinging molecules reached complete thermalequilibrium with the surface before leaving the surface. Used forthermal accommodation coefficients. SP-7 1968accountingThe practice and system of recording and summarizing businessand financial transactions and reporting as well as verifying andanalyzing their results. 1982accretion disksRotation disks of matter surrounding an astronomical object, suchas a star, galactic nucleus, black hole, etc., which is accumulatedgravitationally by the object. 1982accumulatorsDevices or apparatus that accumulate or store. Used forcollectors. SP-7 1968accumulators (computers)In computer technology, devices which store a number and uponreceipt of another number add it to the number already storedand store the sum. SP-7 1968accuracyThe degree of agreement of the measurements with the true valueof the magnitude of the quantity measured. Used for error bandand fidelity. ASTM (E 319, E-41) 1968ACE programA NASA program started in 1975 to reduce fuel consumption fortransport aircraft through the study of structural and aerodynamicenergy efficiency as well as engine energy efficiency consisting ofengine component improvement, new energy efficient engines, andadvanced turbopropellers. The acronym stands for aircraft energyefficiency. Used for Aircraft Energy Efficiency program and energyefficiency transport program. 1982acetationUse acetylationacetylationSubstitution of an acetyl radical for an active hydrogen. Specifically,formation of cellulose acetate from cellulose. Used for acetation.

ASTM (0 1695,0-23) 1968acid rainLow pH rainfall resulting from atmospheric reactions of aerosolscontaining chlorides and sulfates (or other negative ions). 1977acoustic delay linesDevices used in a communications link or a computer memory inwhich the signal is delayed by the propagation of sound waves.Used for sonic waveguides. SP-7 1968acoustic emissionThe stress and pressure waves generated during dynamicprocesses in materials and used in assessing structural integrityin machined parts. 7977acoustic excitationThe process of inducing vibration in a structure by exposure tosound waves. SP-7 1968

2NASAISTIF FRAME NUMBER 2

acoustic generatorsUse sound generatorsacoustic levitationMethod by which molten materials in space are suspended duringprocessing experiments in the low gravity environment. Also, theuse of very intense sound waves to keep a body suspended,thereby eliminating any container contact. 1980acoustic measurementMeasurement of properties, quantities, or conditions of acousticalLe., mechanical waves. Used for sound measurement. DUE 1968acoustic microscopesInstruments which use acoustic radiation at microwave frequenciesto allow visualization of microscopic detail exhibited in elasticproperties of objects. Used for scanning laser acoustic microscope(SLAM). 1980acoustic radiationUse sound wavesacoustic retrofittingModification, especially of aircraft, to effect noise reduction;specifically the introduction of absorber materials and jet noisesilencers. 1977acoustic streamingUnidrectional flow currents in a fluid that are due to the presenceof sound waves. SP-7 1968acoustic velocityThe speed of propagatic of sound waves. Used for sonic speed,sound barrier, and sound velocity. SP-7 1968acoustic vibrationsUse sound wavesacousticsThe study of sound, including its production, transmission, andeffects. Those qualities of an enclosure that together determineits character with respect to distinct hearing. Used for sound.SP-7 1968ACPL (Spacelab)Use atmospheric cloud physics lab (Spacelab)actinide seriesThe series of elements beginning with actium, Element No. 89,and continuing through lawrencium, Element No. 103.

ASTM (C 859, C-26) 1968actinographsUse actinometersactinometersThe general name for instruments used to measure the intensityof radiant energy, particularly that of the sun. Used for actinographsand emissographs. SP-7 1968activated sludgeA semiliquid mass removed from the liquid flow of sewage andsubjected to aeration and aerobic microbial action. The end productis dark to golden brown, partially decomposed, granular and

7977locculent, and has an earthy odor when fresh.active controlThe automatic activation of various control surface functions inaircraft. 1980


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AEROLOGY

active satellitesSatellites which transmit a signal, in contrast to passive satellites.SP-7 1968

actuatorsMechanisms to activate process control equipment, e.g., valves.Used for cartridge actuated devices, hydraulic actuators, andtriggers. DOE 1968acuityThe keeness of ability to detect and discriminate.

ASTM (E 253, E-18) 1968Ada (programming language)A programming language based on PASCAL, originally developedon behalf of the U6 Department of Defense for use in embeddedcomputer systems. It is named Ada in honor of Augusta AdaByron, countess of Lovelace, primarily due to the fact that shewas the assistant and patron of Charles Babbage and is consideredthe worlds first programmer. 1982adaptationThe adjustment, alteration or modification of an organism to fit itmore perfectly for existence in its environment. SP-7 1968adaptersDevices or contrivances used or designed primarily to fit or adjustone thing to another. Devices, appliances or the like used to altersomething so as to make it suitable for a use for which it was notoriginally designed. SP-7 1968adaptive opticsReal-time optical correction for atmospheric perturbations and othersystem error sources. 1977additivesMaterials or substances added to something else for a specificpurpose. Used for doping (additives). SP-7 1968adductsChemical compounds with weak bonds, e. g., occlusive or Vander Waal bonds. DOE 1968adiabatic demagnetization coolingUse of paramagnetic salts cooled to the boiling point of helium ina strong magnetic field, then thermally isolated and removed fromthe field to demagnetize the salts and attain temperatures of lo( -3)K. 1980adsorbentsMaterials which take up gases by adsorption. SP-7 1968adsorptionThe adhesion of a thin film of liquid or gas to the surface of asolid substance. The solid does not combine chemically with theadsorbed substance. SP-7 1968advanced range instrumentation aircraftAn EC-135 aircraft configured for reception recording and real-timerelay of telemetry data. 1981advanced technology laboratoryAn all-pallet payload utilizing the Space Shuttle and the EuropeanSpacelab and designed to accommodate 8 to 15 experiments permission. 1985Advanced X Ray Astrophysics FacilityUse X Ray Astrophysics Facility

advectionThe process of transport of an atmospheric property solely by themass motion of the atmosphere; also, the rate of change of thevalue of the advected property at a given point. SP-7 1968ae roas sChanging orbit size by utilizing aerobraking, aerocapture, oraeromaneuvering. 1982aerobiologyThe study of the distribution of living organisms freely suspendedin the atmosphere. SP-7 1968aerobrakingChanging orbit size by using the upper atmosphere to createdrag. 1982aerocaptureMaking use of the atmosphere of a planet or planetary satelliteby capturing the object and reducing the orbit size so that itremains in orbit or lands on the body. 1982aerodynamic buzzUse flutteraerodynamic chordsUse chords (geometry)aerodynamic coefficientsAny nondimensional coefficients relating to aerodynamic forces ormoments, such as a coefficient of drag, a coefficient of lift, etc.Used for li ft coefficients. SP-7 1968aerodynamic forcesThe force exerted by a moving gaseous fluid upon a bodycompletely immersed in it. Used for Glauert coefficient. SP-7 1968aerodynamic heatingThe heating of a body produced by the passage of air or othergases over its surface. DOE 1968aerodynamic liftUse liftaerodynamicsThe science that deals with the motion of air and other gaseousfluids, and the forces acting on bodies when the bodies movethrough such fluids, or when such fluids move against or aroundthe bodies. Used for hydroaeromechanics. SP-7 1968aeroelastic research wingsWings that are designed with less than normal stiffness to testdevices that suppress flutter. 1983aeroelasticityThe study of the response of structurally elastic bodies toaerodynamic loads. SP-7 1968aeroembolismThe formation or liberation of gases in the blood vessels of thebody, as brought on by a too-rapid change from a high, or relativelyhigh, atmospheric pressure to a lower one. SP-7 1968aero ogyThe study of the free atmosphere throughout its vertical extent,as distinguished from studies confined to the layer of theatmosphere adjacent to the earths surface. SP-7 1968

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AEROMAGNETO FLUlTER

aeromagneto flutterUse flutteraeromaneuveringChanging orbit size or plane or both by entering the upperatmosphere to create drag or lift or both. 1982aeromaneuvering orbit to orbit shuttleProposed reusable upper stage for the Space Shuttle supersededby the orbit transfer vehicle. Used for AMOOS. 1979ae ronomyThe study of the upper regions of the atmosphere where ionization,dissociation, and chemical reactions take place. SP-7 1968aerosolsDispersions of solid or liquid particles n gaseous media.ASTM (D 1356, 0-22) 968aerospace medicineThat branch of medicine dealing with the effects of flight throughthe atmosphere or in space upon the human body and with theprevention or cure of physiological or psychologicalmalfunctionsarising from these effects. SP-7 1968aerospace safetyThe engineering assessment and analysis of systems, subsystems,and functions of spacecraft, missiles, advanced aircraft and groundsupport in order to identify hazards associated with such systemsand to design procedures that eliminate those hazards or determinetolerable safety levels. 1982aerospace technology transferTechnology transfer germane to aircraft and space vehicles, theirpropulsion, guidance, etc. 1977aerospace vehiclesVehicles capable of flight within and outside the sensibleatmosphere. SP-7 1968aerostatsUse airshipsaerothermodynamicsThe study of aerodynamic phenomena at sufficiently high gasvelocities that thermodynamic properties of gas are important.SP-7 1968aerothermoelasticltyThe study of the response of elastic structures to the combinedeffects of aerodynamic heating and loading. SP-7 1968aerozineA rocket fuel consisting of a mixture of hydrazine and unsymmetricaldimethylhydrazine (UDMH). 1968AFC (control)Use automatic frequency controlafterbodiesCompanion bodies that trail satellites. Sections or pieces of rocketsor spacecraft that enter the atmosphere unprotected behind nosecones or other bodies that are protected for entry. afterparts ofvehicles. Used for cylindrical afterbodies and sterns. SP-7 1968afterburnersUse afterburning

afterburningIrregular burning of fuel left in the firing chamber of a rocket aftercutoff. The function of an afterburner, a device for augmentingthe thrust of a jet engine by burning additional fuel in theuncombined oxygen in the gases from the turbine. Used forafterburners. SP-7 1968afterglowsBroad, high arches of radiance or glow seen occasionally in thewestern sky above the highest clouds in deepening twilight, causedby the scattering effect of very fine particles of dust suspended inthe upper atmosphere. Also, the transient decay of a plasma afterthe power has been turned off. SP-7 1968AGC (control)Use automatic gain controlagricultural aircraftLight aircraft specially equipped for agricultural applications suchas crop dusting. 1979AgRlSTARS projectA multiagency program utilizing Landsat remote sensing data topredict crop yields, land use, and detecting pollution. Used forCrop Inventories by Remote Sensing. 1980agrophysical unitsGeogiaphic areas defined for statistical purposes by AgRlSTARSpersonnel whose boundaries are based on natural rather thanpoli tical lines for the purpose of comparing similar agriculturalregions. 1983AGTUse automated guideway transit vehiclesAH-1G helicopterUS Army designation for the Bell Model 209 Hueycobra attackhelicopter powered by a single Avco Lycoming T53-L-13 turboshaftengine. 1980airThe mixture of gases comprising the earths atmosphere.SP-7 1968air breathing boostersBoosters which are possible substitutes for rocket engines andwhich have inlets for oxygen sources for their engines rather than1981arrying their own oxygen as in a conventional rocket.air conditioningThe simultaneous control of all, or at least three, of those factorsaffecting both the physical and chemical conditions of theatmosphere within any structure. These factors include temperature,humidity, motion, distribution, dust, bacteria, odor, and toxicgases. ASTM (E 41, G-3) 968air cushion landing systemsLanding systems based on the ground effect principle whereby astratum of air is utilized as the aircraft ground contacting medium(in place of landing gear). 1977air lawThe body of domestic and/or international laws dealing withregulations and liabilities in civil or military aviation. 1980

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ALKALINITY

air locksA stoppage or diminution of flow in a fuel system, hydraulic system,or the like, caused by pockets of air or vapor. Also chamberscapable of being hermetically sealed that provide for passagebetween two places of different pressure as between an altitudechamber and the outside atmosphere. SP-7 1968air pollutionThe presence of unwanted material in the air. The term unwantedmaterial here refers to material in sufficient concentrations, presentfor a sufficient time, and under circumstances to interferesignificantly with comfort, health, or welfare of persons, or withthe full use and enjoyment of property. Used for atmosphericimpurities. ASTM (D 1356, 0-22) 1968air sicknessUse motion sicknessair slew missilesSolid propellant rockets utilizing thrust vector control. 1977airborne integrated reconnaissance systemAerial reconnaissance system incorporating various modes ofdetection. Used for AIRS (reconnaissance sys). 1977airborne radar approachThe use of airborne radar for aircraft approach control -- the radarcursor technique. 1980aircraft construction materialsA general term designating the materials used in manufacturingan aircraft. 1976Aircraft Energy Efficiency programUse ACEE program

aircraft noise predictionUse noise prediction (aircraft)aircraft power suppliesElectrical sources for the normal operation of aircraft. 1984aircraft runupFinal engine check prior to takeoff. 1980aircraft spinA prolonged stall in fixed-wing aircraft characterized by a sustainedspiral descent, usually with the nose down. 1979airfoil characteristicsUse airfoilsairfoil oscillationsPeriodic motions experienced by airfoils in aerodynamicconditions. 1987airfoilsStructures, pieces, or bodies, originally likened to foils or leavesin being wide and thin, designed to obtain a useful reaction onthemselves in their motion through the air. Used for airfoilcharacteristics. SP-7 1968airframesThe assembled structural and aerodynamic components of anaircraft or rocket vehicle that support the different systems andsubsystems integral to the vehicle. SP-7 1968

airglowThe quasi-steady radiant emission from the upper atmosphere asdistinguished from the sporadic emission of the auroras. Used foratmospheric emission. SP-7 1968airport securityOrganization of trained security personnel, surveillance andscreening devices, and procedures used for the protectionof airportand airline property, aircraft, passengers, employees, and visitorsfrom injury, air piracy, and other unauthorized acts. 1977AIRS (reconnaissance sys)Use airborne integrated reconnaissance systemairshipsPropelled and steerable dirigibles dependent on gases for flotation.Used for aerostats and dirigibles. DOE 1968airspaceThe atmosphere above a particular port ion of the earth, usuallydefined by the boundaries of an area on the surface projectedperpendicularly upward. SP-7 7968Aitken nucleiMicroscopic particles in the atmosphere which serve ascondensation nuclei for droplet growth during the rapid adiabaticexpansion produced by an Aitken dust counter. 1978albedoThe ratio of the amount of electromagnetic radiation reflected bya body to the amount incident incident upon it, often expressedas a percentage, as, the albedo of the earth is 34%. SP-7 1968aldehydesCarbonyl groups to which a hydrogen atom is attached; the firststage of an alcohol; - CHO. ASTM (D 1695, 0-23) 1968Alfven wavesUse magnetohydrodynamic wavesAlGaAsUse aluminum gallium arsenidesalgaeAny plants of a group of unicellular and multicellular primitiveorganisms that include the Chlorella, Scenedesmus, and othergenera. Used for algal bloom. SP-7 1968algal bloomUse algae

algorithmsSpecial mathematical procedures for solving a particular type ofproblem. SP-7 1968alkali metalsMetals in group IA of the periodic system; namely, lithium, sodium,potassium, rubidium, cesium, and francium. SP-7 1968alkali vapor lampsLamps in which light is produced by an electric discharge betweenelectrodes in an alkali vapor at low or high pressures. 1977alkalinityThe state of being alkaline. 1981



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ALLOYS

alloysSubstances having metallic properties and being composed oftwo or more chemical elements of which at least one is anelemental metal. SP-7 1968alluviumSoil, the constituents of which have been transported in suspensionby flowing water and subsequently deposited by sedmentation.ASTM (0 653, 0-18) 1973aloha systemA multiple random access communications scheme in which thereis a nonfixed allocation of channel capacity, so that the channelis available to any terminal whenever it has a packet ready fortransmission. 1981alpha decayThe radioactive transformation of a nuclide by alpha-particleemmission. SP-7 1968alpha particlesPositively charged particles emitted from the nuclei of certain atomsduring radioactive disintegration. Used for alpha radiation.SP-7 1968alpha radiationUse alpha particlesAlpine meteorologyWind, precipitation, atmospheric physics, and other climatologicalphenomena peculiar to the Alps and/or other similar mountainousareas. 1979altimetersInstruments for measuring height above a reference datum.

SP-7 1968altitudeIn astronomy, angular displacement above the horizon. Also height,especially radial distance as measured above a given datum, asaverage sea level. SP-7 1968altitude acclimatizationA physiological adaptation to reduced atmospheric and oxygen

altitude sicknessIn general, any sickness brought on by exposure to reduced oxygen

pressure. SP-7 1968

tension and barometric pressure. SP-7 1968aluminidesIntermetallic compounds of aluminum and a transition metal. 1987aluminum arsenidesBinary compounds of aluminum with negative, trivalent arsenic.1978aluminum boron compositesStructural materials composed of aluminum alloys reinforced withboron fibers (filaments). 1976aluminum gallium arsenidesCompounds exhibiting characteristics suitable for use in laserdevices, light-emitting diodes, solar cells, etc. Used for AIGaAs.

1978aluminum graphite compositesStructural materials composed of aluminum alloys reinforced withgraphite. 1976

alveolar airThe respiratory air in the alveoli (air sacs) deep within the lungs.SP-7 1968alveoliThe terminal air sacs deep within the lungs. SP-7 1968AmaltheaInnermost satellite of Jupiter. 1978ambient temperatureTemperature of surrounding medium. Used for environmentaltemperature. DOE 1968AMOOSUse aeromaneuvering orbit to orbit shuttleAmor asteroidOne group of earth-approaching asteroids with orbits between theplanets Mars and Jupiter. Used for Minor Planet 1221. 1978amphibolesA group of dark, rock-forming, ferromagnesian silicate mineralsclosely related in crystal form and composition. DOE 1968amplifiersDevices which enable an input signal to control a source of powerwhose output is an enlarged reproduction of the essentialcharacteristics of the signal. Used for electronic amplifiers.SP-7 1968amplitude modulationIn general, modulation in which the amplitude of a wave is thecharacteristic subject to variation. SP-7 1968amplitudesThe maximum value of the displacement of a wave or other periodicphenomenon from a reference position. Also, angular distancenorth or south of the prime vertical; the arc of the horizon, or theangle at the zenith between the prime vertical and a vertical circle,measured north or south from the prime vertical to the verticalcircle. SP-7 1968ampoulesGlass containers designed to be filled and sealed by fusion of theglass neck. ASTM (C 162, C-14) 1968AMTVUse automated mixed traffic vehicles

analog computersComputers that work on the principle of measuring, as distinguishedfrom counting, in which the input data is analogous to ameasurement continuum such as linear lengths, voltages, orresistances which can be manipulated by the computer.SP-7 1968analog to digital convertersDevices for converting non-digital information into digits. Used fordigitizers. DOE 1968analysis (mathematics)That part of the field of mathematics which arises from the calculusand which deals primarily with functions. 1968

6NASAlST lF FRAME NUMBER 6


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ANTIPARTICLES

analysis of varianceA systematic statistical procedure for determining the sources andthe magnitudes of the errors present in a measurement process,and for assessing the significance of differences between materials,processes, or test methods under study.ASTM ( 0 3980, D-1) 1971andes teVolcanic rock composed essentially of andesine and one or moremafic constituents. DOE 1968angle of attackThe angle between a reference line fixed with respect to an airframeand a line in the direction of movement of the body. SP-7 1968angles (geometry)The inclination to each other of two intersecting lines, measuredby the arc of a circle intercepted between the two lines formingthe angle, the center of the circle being the point of intersection.

SP-7 1968angular accelerationThe rate of change of angular velocity. SP-7 1968angular motionUse angular velocityangular resolutionSpecifically the ability of a radar to distinguish between two targetssolely by the measurement of angles. SP-7 1968angular velocityThe change of angle per unit time; specifically, in celestialmechanics, the change in angle of the radius vector per unit time.Used for angular motion. SP-7 1968Anik satellitesA series of geostationary communication satellites operated byTelesat which is partly owned by the Canadian government andpartly owned by private enterprise. The name 'Anik' is derivedfrom an Eskimo word meaning 'brother'. It was so designatedbecause of its par tial use in the Far North. 1983anisotropyHaving different properties in different directions. Used fornonisotropy, onisotropy, photothermotropism, and thermotropism.

ASTM (D 653, 0-18) 1968annealingApplication of heat energy to a material cooling at a suitable rateto relieve stresses, change certain properties, improvemachinability, or for realignment of atoms in a distortedlattice ascaused, for example, by radiation damage. SP-7 1968annular ductsRing-shaped openings for the passage of fluids (gases, etc.)designed for optimum aerodynamic flow properties for theapplication involved. 1979annular suspension and pointing systemIn the Shuttle era, high accuracy pointing and stabilization of anexperiment payload. 1980anodesThe positive pole or electrode of any electron emitter, such as anelectron tube or an electric cell. SP-7 1968

anodic strippingThe removal of metal coatings. 1!WOanodizingAn electrolytic oxidation process in which the surface of a metal,when anodic, is converted to a coating having desirable protective,decorative, of functional properties. ASTM (6 74, 6-8) 1!768anomaliesIn general, deviations from the norm. SP-7 1968anorthositeA group of essentially monominefalic plutonic igneous rockscomposed almost entirely of plagioclass feldspar. DOE 1968anoxiaA complete lack of oxygen available for physiological use withinthe body. SP-7 1968antenna arraysSystems of antennas coupled together to obtain directional effects,or to increase sensitivity. SP-7 1968antennasConductors or systems of conductors for radiating or receivingradio waves. SP-7 1968anthropologyThe study of the interrelations of biological, cultural, geographical,and historical aspects of man. DOE 1968anticlinesGeologic formations characterized by folds the core of whichcontain stratigraphically older rocks; they convex upward. Usedfor anticlinoria. DOE 1.974anticlinoriaUse anticlinesantifoulingMeasures taken to prevent corrosion or the accumulation of organicor other residues or growths on operating machanisms, especiallyin underwater environments. 1.981antigravityA hypothetical effect that would arise from cancellation by someenergy field of the effect of the gravitational field of the earth orother body. SP-7 1968antimisting fuelsFuels which have an additive to reduce misting and thus createsafer fuels. 1985antinodesEither of the two points on an orbit where a line in the orbitplane, perpendicular to the line of nodes and passing through thefocus intersects the orbit. Also a point, line, or surface in a standingwave where some characteristic of the wave field has maximumamplitude. SP-7 1968antioxidantsCompounding ingredients used to retard deterioration caused byoxidation. ASTM (D 1566, D-1 1 ) 1968antiparticlesParticles with a charge of opposite signs to the same particles innormal matter. SP-7 1968



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ANTIPODES

antipodesAnything exactly opposite to something else. Particularly, that pointon the earth 180 deg. from a given place. SP-7 1968

antiquitiesMan made objects or surviving parts or fragments from the past.1985antiradiation missilesMissiles that attack radiating targets such as radar transmitters,etc. 1980AOIPSUse atmospheric 8 oceanographic inform sysAPL (programming language)A Programming Language is a high level interactive computerlanguage primarily designed for mathematical applications. It wasdeveloped by Kenneth lverson in 1962. It is characterized byextensive operators and array handling capability. NASA Goddardwas one of the first users and was instrumental in introducingAPL to the computer community. 1983apneaUse respirationApollo asteroidsEarth grazing asteroids in orbits between Mars and Jupiter, andcrossing the earths orbit. This group contains 19 knownasteroids. 1978approach and landing tests (STS)A series of flight maneuvers involving the Space Shuttle. 1978aquatic plantsPlants growing in or on water 1981aquicultureThe cultivation (breeding, raising, and harvesting) of fish, mollusks,shellfish, and/or other aquatic life as sources of food. 1977aquifersBodies of rock that contain sufficient saturated permeable materialto conduct ground water and to yield economically significantquantities of ground water to wells and springs. DOE 1974aragoniteA white, yellowish, or gray orthorhombic mineral, that containscalcium carbonate. DOE 1968archaebacteriaOrganisms belonging to the taxonomic kingdom of the same namewhich are characterized by distinct t- and r-RNAs, the absence ofpeptoglycan cell walls and their possible replacement by aproteinaceous coat, ether-linked lipids from phytanyl chains, andoccurance in unusually harsh habitats, e.g., methane, halide andthermoacidic environments. These hardy bacteria are significantin the study of the origin of li fe. 1987architecture (computers)The design of system and logic organization and information flowrelationships in a computer rather than the circuit and componentfeatures. 1976arguments (mathematics)Use independent variables


ArielA satellite of Uranus orbiting at a mean distance of 192,000kilometers. SP-7 1986

Ariel 5 satelliteOne in a series of artificial satellites launched for Britain by theUnited States. 1976Aries sounding rocketThe largest in terms of weight and volume of the sounding rockets.It has a 44 inch payload capacity. 1982ARlP (impact prediction)Use computerized simulationARPA computer networkThe Advanced Research Projects Agency of the Department ofDefense nationwide computer network incorporating digitalcommunication between large numbers of dissimilar computers aswell as direct access to programs, data, storage, etc. shared byall terminals. 1977arrhythmiaAbsence of rhythm, as, for example, in heart beat. SP-7 1968arrow wingsAircraft wings of V-shaped planform, either tapering or of constantchord, suggesting a stylized arrowhead. SP-7 1968artificial gravityA simulated gravity established within a space vehicle by rotationor acceleration. SP-7 1968artificial intelligenceA subfield of computer science concerned with the concepts andmethods of symbolic inference by a computer and the symbolicrepresentation of the knowledge to be used in making inferences.Used for machine recognition. DOE 1968artificial satellitesMan-made satellites. SP-7 1968aspect ratioThe ratio of the square of the span of an airfoil to the total airfoilarea, or the ratio of its span to its mean chord. SP-7 1968asphaltA dark brown to black cementitious material, in which thepredominating constituents are bitumens which occur in nature orare obtained in petroleum processing.

ASTM (0 1079, 0-8 , 0 - 4 ) 1968asphaltenesComponents of bitumens that are soluble in carbon disulphide butnot in paraffin naphtha, consti tute the solid dispersed particles ofthe bitumens, and consist of high molecular weight hydrocarbons.

1980aspirationUse vacuumassociation reactionsGas phase chemical processes in which two molecular speciesand B react to form a larger molecule AB. In astrophysics theseprocesses are involved in the condensation of small gaseousmolecules into larger species. 1980


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ATMOSPHERIC OPTICS

associative processing (computers)Byte-variable computer processing with multifieldsearch, arithmetic,and logic capability. 1977asteroid beltsThe location of the orbits of most of the minor planets (estimatedat a half million asteroids) between Mars and Jupiter; about 2000asteroids have been assigned numbers and names. 1978asteroid captureThe transfer of an asteriod or comet from the influence of aplanet into that of another planet or neutral satellite.asteroid missionsSpace missions for the study of asteroids and related celestialbodies. 1978

1979

asteroidsSmall celestial bodies revolving around the sun, most having orbitsbetween those of Mars and Jupiter. SP-7 1968astrobiologyUse exobiologyastrodynamlcsThe practical application of celestial mechanics, astroballistics,propulsion theory, and allied fields to the problem of planning anddirecting the trajectories of space vehicles. SP-7 1968astrolabesInstruments designed to observe the positions and measure thealtitudes of celestial bodies. 1981astronomical coordinatesCoordinates defining a point on the surface of the earth, or of thegeoid, in which the local direction of gravity is used as areference. SP-7 1968astronomyThe science that treats of the location, magnitudes, motions, andconstitution of celestial bodies and structures. Used for celestialobservation. SP-7 1968astrophysicsA branch of astronomy that treats of the physical properties ofcelestial bodies, such as luminosity, size, mass, density,temperature, and chemical composition. Used for

asymptotic propertiesProperties of any mathematical relation or corresponding physicalsystem characterized by an approach to a given value as anexpression, containing a variable, tends to infinity. 1984ATARSUse automatic traffic advisory and resolutionatelectasisCollapsed or airless state of all or part of the lung.athodydsUse ramjet enginesatmospheric 6 oceanographic inform sysA data system designed primarily for the interactive manipulationof meteorological satellite images. Capabilities include displaying,analyzing, storing, and manipulating digital data in the field ofmeteorology and earth resources. Used for AOIPS. 1985

geoastrophysics. SP-7 1968

SP-7 1968

atmospheric chemistryStudy of the production, transport, modification, and removal ofatmospheric constituents in the troposphere and stratosphere.DOE 7968atmospheric circulationGlobal or hemispheric air movements which can be treated byequations of motion in contrast to atmospheric diffusion which issmall random movement not amenable to treatment by theseequations. Used for wind circulation. DOE 1968atmospheric cloud physics lab (Spacelab)A NASA Spacelab mission involving cloud physics experiments inzero gravity environment. Also known as ACPL. Used for ACPL(Spacelab) and zero-g ACPL (Spacelab). 1976atmospheric conditionsUse meteorologyatmospheric correctionRemoval of the effects of the intervening atmosphere from satelliteimagery. 1983atmospheric electricityElectrical phenomena, regarded collectively, which occur in theearths atmosphere. Also the study of electrical processes occiiringwithin the atmosphere. SP-7 1968atmospheric emissionUse airglowatmospheric entryThe penetration of any planetary atmosphere by any object fromouter space; specifically, the penetration of the earths atmosphereby a manned or unmanned capsule or spacecra ft. Used forplanetary entry. SP-7 1968atmospheric general circulation experimentModel experiment of the earths atmospheric circulation asproposed for a Spacelab flight on which a liquid contained betweentwo concentric spheres is subjected to rotation. The thermal drivingforce will be a stable radial temperature gradient and an unstablelatitudinal gradient. 1980atmospheric impuritiesUse air pol lutionatmospheric lasersThe theoretical phenomena whereby the upper atmosphere is usedas the lasing medium. 1981atmospheric loadingUse pol lution transportatmospheric noiseUse atmosphericsatmospheric opticsThe study of the optical characteristics of the atmosphere and ofthe optical phenomena produced by the atmospheres suspensoidsand hydrometeors. It embraces the study of refraction, reflection.diffraction, scattering, and polarization of light, but is not commonlyregarded as including the study of any other kinds of radiation.

SP-7 1970



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ATMOSPHERIC PRESSURE

atmospheric pressureThe pressure at any point in an atmosphere due solely to theweight of the atmospheric gases above the point concerned. Usedfor barometric pressure. SP-7 1968atmospheric radiationInfrared radiation emitted by or being propagated through theatmosphere. SP-7 1968atmospheric refractionRefraction resulting when a ray of radiant energy passes obliquelythrough an atmosphere. SP-7 1968atmospheric shellsUse atmospheric stratificationatmospheric soundingMeasurement of atmospheric phenomena generally withinstruments carried aloft by spacecraft, rockets, etc. 1980atmospheric stratificationThe presence of strata or layers in the earths atmosphere. Usedfor atmospheric shells. SP-7 1968atmospheric tidesDefined in analogy to the oceanic tide as an atmospheric motionon a worldwide scale, in which vertical accelerations are neglected(but compressibility is taken into account). SP-7 1968atmosphericsThe radiofrequency electromagnetic radiations originating,princ ipally, in the i rregular surges of charge in thunderstormlightning discharges. Atmospherics are heard as a quasi-steadybackground of crackling noise (static) in ordinary amplitudemodulated radio receivers. Used for atmospheric noise andsferics. SP-7 1968atomic clocksTimekeeping devices controlled by the frequency of the naturalvibrations of certain atoms. SP-7 1968atomic massUse atomic weightsatomic weightsThe weight of an atom according to a scale of atomic weightunits, awu, valued as one-twelfth the mass of the carbon atom.Used for atomic mass. SP-7 1971attenuationReducing in intensity. SP-7 1969attenuation coefficientsA measure of the space rate of attenuation of any transmittedelectromagnetic radiation. SP-7 1968attenuatorsDevices for measuring attenuation. They are usually calibrated indB (decibels). ASTM (E 500, E-7) 1968attitude (inclination)The position or orientation of an aircraft, spacecraft, etc., either inmotion or at rest, as determined by the relationship between itsaxes and some reference line or plane or some fixed system ofreference axes. Used for spatial orientation, tilt, and tilting.

SP-7 1968

attitude controlThe regulation of the attitude of an aircraft, spacecraft, etc. Alsoa device or system that automatically regulates and correctsattitude, especially of a pilotless vehicle. SP-7 1968attitude gyrosGyro-operated flight instruments that indicate the attitude of anaircraft or spacecraft with respect to a reference coordinate systemthroughout 360 degrees of rotation about each axis of the craft.

SP-7 1968audio dataUseful information at audio signal frequency.audio frequenciesFrequencies corresponding to normally audible sound waves.

1984

SP-7 1968audio signalsSignals with a bandwidth of less than 20 kilohertz. 1984auditory sensation areasIn acoustics, the frequency region enclosed by the curves definingthe threshold of pain and the threshold of audibility. SP-7 1968aufeis (ice)Icing of ground or river water in Arctic areas with continuouspermafrost on which the water has continued to flow. 1980auroral activityUse aurorasauroral zonesRoughly circular bands around either geomagnetic pole abovewhich there is a maximum of auroral activity. The zones lie about10deg. to 15 deg. of geomagnetic latitude from the geomagneticpoles. SP-7 1968aurorasSporadic radiant emissions from the upper atmosphere over middleand high latitudes. Used for auroral activity and polar auroras.

SP-7 1968austeniteA solid solution of carbon in gamma-iron. DOE 1968austenitic stainless steelsSteels having at room temperature a microstructure consisting, atleast predominantly, of austenite. Their austenitic microstructureis attained above all by alloying conditions, e.g.. manganese andnickel. DOE 1968autocollimatorsUse collimatorsautocorrelationIn statistics, the simple linear internal correlation of members of atime series (ordered in time or other domains). SP-7 1968automated en route ATCAn air traffic control technology which allows computers to makedecisions about conflict resolution, the generation of clearances,and their automatic transmission, with the operator standing by totake over in an emergency. 1981automated guideway transit vehiclesA system of a large number of captive vehicles traveling at relativelyclose headways on an exclusive guideway controlled by a computer.Used for AGT. 1979



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BACKWARD FACING STEPS

automated mixed traffic vehiclesLow speed, surface vehicles automatically operated and controlledin a pedestrian environment by following a buried wire in theroadways sensing obstacles and stopping at predetermined spotsfor passenger exit and entry. Used for AMTV. 1978automated pilot advisory systemAn airport advisory system and an air traffic advisory systemdesigned to improve airport and air traffic advisories at high densityuncontrolled airports. 1981automated radar terminal systemRadar tracking system for use in a terminal area. Primary andsecondary radar targets are detected and data for the two arecorrelated for transmission to a central computer. 1980automatic controlControl of devices and equipment, including aerospace vehiclesby automatic means. Used for self regulating. SP-7 1968

automatic data processingUse data processingautomatic frequency controlAn arrangement whereby the frequency of an oscillator isautomatically maintained within specified limits. Used for AFC(control). SP-7 1968automatic gain controlA process by which gain is automatically adjusted as a functionof input or other specified parameter. Used for AGC (control).SP-7 1968automatic pilotsEquipment which automgtically stabilizes the attitude of a vehicleabout its pitch, roll, and yaw axes. Used for autopilots. SP-7 1968automatic rocket impact predictorsUse computerized simulationautomatic traffic advisory and resolutionGround based collision avoidance system using the surveillanceand data link capabilities of the discrete address beacon system(DABS). Used for ATARS. 1980automatic weather stationsWeather stations at which the services of observers are notrequired. They are usually equipped with telemetric apparatus.

1976autonomous spacecraft clocksStandard Time scale instruments aboard spacecraft with provisionsfor synchronization with existing satellite-based system (globalpositioning system, for example). 1980autopilotsUse automatic pilotsautotrophsOrganisms capable of synthesizing organic nutrients directly fromsimple inorganic substances such as carbon dioxide and inorganicnitrogen. DOE 1968autumnThe season of the year between summer and winter. Its beginningis marked by the autumnal equinox and its end by the wintersolstice. 1985

aviation meteorologyWeather conditions and meteorological studies pertaining toaeronautics. 1.987

awardsDistinctions that are bestowed upon a person or persons due totheir special contributions to a field. 1982AXAFUse X Ray Astrophysics Facilityaxes (coordlnates)Use coordinatesaxial modesRegimes of vibration along a given axis. 1.981axial strainLinear strain in a plane parallel to the longitudinal axis of thespecimen. Used for axisymmetric deformation and uniaxial strain.

ASTM (E 6.E-28) 1.968axisymmetric deformationUse axial strainazimuthHorizontal direction or bearing. Used for solar azimuth. SP-7 1.968azolesCompounds that contain a five-membered heterocylic ringcontaining one or more nitrogen atoms. DOE 1.968

BB-A-W devicesUse bulk acoustic wave devicesbabbitt metalAny of the white alloys composed primarily of tin or lead and oflesser amounts of antimony, copper, and other metals, and usedfor bearings. 1976background noiseIn recording and reproducing, the total system noise independentof whether or not a signal is present. The signal is not to beincluded as part of the noise. In receivers, the noise in the absenceof signal modulation on the carrier. SP-7 1.968backingsUse backupsbackupsItems kept available to replace items which fail to performsatisfactorily. Items under developement intended to perform thesame general functions of another item also under developmentperforms. Used for backings. SP-7 1968backward differencingA method of solving a parabolic problem for approximating a timederivative in terms of a previous time step. 1.982backward facing stepsA step structure which faces an oncoming flow. Used for rearwardfacing steps. 1982

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BACKWARD WAVES

backward wavesIn traveling wave tubes, waves whose group velocity is oppositeto the direction of electron-stream motion. SP-7 1968bactericidesAgents that destroy microorganisms.Used for germicides. DOE 1968bafflesPlates that regulate the flow of a fluid, e.g., a heat exchanger,boiler flue, or automotive muffler. DOE 1968bakeoutUse degassingbalanced amplifiersUse push-pull amplifiersball lightningA relatively rare form of lightning, consisting of a reddish, luminousball, of the order of one foot in diameter, which may move rapidlyalong solid objects or remain floating in midair. Hissing noisesemanate from such balls, and they sometimes explode noisily butmay also appear noiselessly. SP-7 1973ballistic camerasGround-based cameras using multiple exposures on the same plateto record the trajectories of rockets. SP-7 1968ballistic missilesMissiles designed to operate primarily in accordance with the lawsof ballistics. SP-7 1968ballistic trajectoriesTrajectories followed by a body being acted upon only bygravitational forces and the resistance of the medium through whichit passes. SP-7 1968ballisticsThe science that deals with the motion, behavior and effects ofprojectiles, especially bullets, aerial bombs, rockets or the like;the science or art of designing and hurling projectiles so as toachieve a desired performance. SP-7 1968bandgapUse energy gaps (solid state)bandpass filtersWave filters having a single transmission band; neither of thecut-off frequencies being zero or infinity. ASTM (E268, E-21) 1968bang-bang controlUse off-on controlBarany chairA kindof chair inwhich a person is revolved to test his susceptibilityto vertigo. It is named after the Swedish physician Robert Baranywho lived from 1876 to 1936. SP-7 1968barchansUse dunesbaroclinic instabilityHydrodynamic instability arising from the existence of a meridionaltemperature gradient (and hence a thermal wind) in an atmospherein quasigeostrophic equilibrium and possessing static stability.1980

baroclinityThe state of stratification in a fluid in which surfaces of constantpressure (isobaric) intersect surfaces of constant density (isoteric).The number, per unit area, of isobaric-isoteric solenoids intersectinga given surface is a measure of baroclinity. SP-7 1968barometersInstruments used to measure atmospheric pressure.barometric pressureUse atmospheric pressurebarotropismThe state of a fluid in which surfaces of constant density (ortemperature) are coincident with surfaces of constant pressure; itis the state of zero baroclinity.barred galaxiesSpiral galaxies whose nuclei are in the shape of bars at the endsof which the spiral arms begin. About one fifth of all spiral galaxiesare barred spirals. 1978barricadesUse barriersbarrier injection transit time diodesUse Barritt diodesbarriersAny materials limiting passage through itself of solids, liquids,semisolids, gases, or forms of energy such as ultraviolet light.

SP-7 1968

SP-7 1968

Used for barricades and obstacles. ASTM (F 17, F-2) 1968Barritt diodesBarrier injection transit time diodes that operate similarly to IMPATTdiodes. The operating frequencies are determined by the transittimes across the drift. Used for barrier injection transit timediodes. 1980barycenterUse center of gravitybaryon resonanceAn anomaly found in scattering cross sections indicating theexistence of an unstable, excited state baryon. 1968base flowFluid flow at the base or extreme aft end of a body.base pressureIn aerodynamics, the pressure exerted on the base, or extremeaft end, of a body, as of a cylinderical or boattailed body or of a

1968

blunt-trailing-edge wing, in a fluid flow. SP-7 1968bathymetersInstruments that measure the ocean depths and check thetopography of the ocean floor. Used for bathymetry. DO 1968bathymetryUse bathymetersbauxiteA farruginous aluminium hydroxide rock consis ting of severalminerals. It is the principle source for aluminum. DOE 1968Bayard-Alpert ionization gagesIonization vacuum gages using a tube with an electrode structuredesigned to minimize x ray induced electron emission from theion collector. SP-7 1968

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BIOCHEMISTRY

beaconsLights, groups of lights, electronic apparatus, or other devicesthat guide, orient, or warn aircraft, spacecraft, etc. in flight.SP-7 1968beam currentsCurrents incident on specimens by primary particle sources.ASTM (E673, E-42) 1968beam injectionThe introduction of a particle radiation beam into a plasma orionized gas for the purpose of diagnostics, plasma control, or thestudy of beamlplasma interactions. 1980beam interactionsA general term for interactions between various types of beamswith each other or with plasmas or substances. 1981beam neutralizationNeutralization that takes place by means of charge exchange witha neutral gas. 1981beam rider guidanceSystem for guiding aircraft, spacecraft, or missiles, along a desiredpath by means of a radar beam, light beam, etc. The center ofthe beam axis forms a line along which the vehicle senses itslocation and corrects its course relative to the beam axis. 1977beam splittersPartially reflecting mirrors which permit some incident light to passthrough and reflect the remainder. SP-7 1968beatUse synchronismbeat frequenciesThe frequencies obtained when two simple harmonic quantities ofdifferent frequencies f l and f2 are superimposed. The beatfrequency equals f l f2. SP-7 1968Beech 99 aircraftLight, low-wing aircraft manufactured by Beechcraft. 1977behaviorThe way in which an organism, organ, body, or substance acts inan environment or responds to excitation, as the behavior of steelunder stress, or the behavior of an animal in a test. SP-7 1968Bell 214A helicopterSixteen-seat utility helicopter. 1980bellowsMechanical structures with walls like those of an accordion.

DOE 1968bend testsDuctility tests in which specimens are bent through an arc ofknown radius and angle. 1985bends (physiology)Use decompression sicknessBernoulli equationUse Bernoulli theorem

Bernoulli theoremIn aeronautics, a law or theorem stating that in a flow ofincompressible fluid the sum of the static pressure and the dynamicpressure along a streamline is constant if gravity and frictionaleffects are disregarded. It is named for Daniel Bernoulli, a Swissscientist who lived from 1700 to 1782. Used for Bernoulliequation. SP-7 1968BESS (satellite)A proposed NASA primate biomedical experiment scientific satellitethat was never developed. Used for biomedical experiment scientificsatellite. 1577beta factorIn plasma physics, the ratio of the plasma kinetic pressure to Ihemagnetic pressure. 1580beta interactionsUse weak interactions (field theory)

betatronsParticle accelerators in which magnetic induction is used toaccelerate electrons. SP-7 1968biasA constant or systematic error as opposed to a random error. Itmanifests itself as a persistent positive or negative deviation ofthe method average from the accepted reference value.

ASTM (E 180, E-15) 1968bifurcation (biology)The separation or branching into two parts, areas, aspects orconnected segments, of anatomical systems or functions. 1578bimetric theoriesTheories of gravitation. 1980binary codesCodes composed of a combination of entities each of which c:anassume one of two possible states. Each entity must be identifiablein time or space.binary starsSystems of two stars revolving about a barycenter.

SP-7 1969

SP-7 1968bioassayA standardized procedure for the determination of the effects ofan environmental variable or substance on living organisms. Usedfor biological analysis. ASTM (0 1129,0-19) 1668bioastronauticsThe study of biological, behavioral, and medical problems pertainingto astronautics. This includes systems functioning in theenvironments expected to be found in space, vehicles designedto travel in space, and the conditions on celestial bodies earth.SP-7 1968biochemical oxygen demandThe amount of oxygen necessary for the oxidative decompositionof a material by microorganisms. The amount of oxygen consunledin mg/l of water (or waste water) over a period of 5 days at 20deg. C under laboratory conditions. Used for BOD. DO 7976biochemistryChemistry dealing with the chemical processes and compoundsof living organisms. SP-7 1968

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BlOCOMPATlBlLlTY

biocompatibilityCompatibil ity of substances with living tissues and bloodcomponents. 1980

bioconversionThe transformation of algae and/or other biomass materials insuccessive stages to aliphatic organic acids to aliphatichydrocarbons to diesel and/or other liquid fuels. 1980biodegradabilityThe characteristic of a substance that can be decomposed bymicroorganisms. 1977biodynamicsThe study of the effects of dynamic processes (motion,acceleration, weightlessness, etc.) on l iving organisms. Used forbiomechanics. SP-7 1968biofeedbackOriginally confined to the presenting of a subject with sensoryinformation about his ongoing physiological activities, it nowincludes the controlling of specific physiological activities throughtrained mental effort. 1983biological analysisUse bioassaybiological modelsUse bionicsbiological models (mathematics)Mathematical models for living systems. 1980biomagnetismMagnetic fields surrounding parts or the whole of a living biologicalsystem; also, the effects of magnetism on parts or the whole of abiological entity. 1977biomassThe dry weight of living matter in a given area expressed in termsof mass or weight per unit of volume or area. 1985biomechanicsUse biodynamicsbiomedical experiment scientific satelliteUse BESS (satellite)bionicsThe study of systems, particularly electronic systems, whichfunction after the manner characteristic of, or resembling livingsystems. Used for biological models and biosimulation. SP-7 1968bioreactorsBiological processors to remove or produce certain chemicals ora particular chemical. 1981bioregenerative life support systemsUse closed ecological systemsbiosatellitesArtificial satellites which are specifically designed to contain andsupport man, animals, or other living material in a reasonablynormal manner for a adequate period of time and which, particularlyfor man and animals, posesses the proper means for safe returnto the earth. SP-7 7968biosimulationUse bionics

biosphereThat transition zone between earth and atmosphere within whichmost forms of terrestrial life are commonly found: the outer portionof the geosphere and inner or lower portion of the atmosphere.

SP-7 1976Biot numberA standard heat transfer dimensionless number. 1985biotechnologyThe application of engineering and technological principles to thelife sciences. SP-7 1968biotelemetryThe remote sensing and evaluation of life functions, as, e.g., inspacecraft and artificial satellites. Used for physiologicaltelemetry. SP-7 1968biotiteA widely distributed and important rock-forming mineral of the micagroup. Used for kimberlite. DOE 1968bipolarityCapability of assuming negative or positive values. 1981bipropellantsUse liquid rocket propellantsbirefringenceA double-refraction phenomenon in which an unpolarized beam oflight is divided into two beams with different directions and relativevelocities of propagation. The amount of energy transmitted alongan optical path through a crystal which exhibits birefringencebecomes a function of crystalline orientation. Used for Pockelseffect. ASTM (F 120, F-1) 1968bistable amplifiersUse flip-flopsbistatic radarUse multistatic radar

bistatic reflectivityThe characteristic of a reflector which reflects energy along aline, or lines, different from, or in addition to, that of the incidentray. SP-7 1968bit error rateThe number of erroneous bits or characters received from somefixed number of bits transmitted. 1983bitumensDark-colored (solid, semisolid, or viscous) cementitious substances,natural or manufactured, composed principally of high molecularweight hydrocarbons, of which asphalts, tars, pitches, andasphaltenes are typical. ASTM (0 8, -4) 1968BL lacertae objectsOne of a class of astronomical objects exhibiting; (1 ) rapid variationsin intensity at radio, infrared, and optical wavelengths: (2) energydistributions largely at infrared wavelengths; (3) absence of discretefeatures in low dispersion spectra; and (4) strong and rapidly varyingpolarization at visual and radio wavelengths. 1978

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BOOSTGLIDE VEHICLES

black body radiationThe electromagnetic radiation emitted by an ideal black body; it isthe theoretical maximum amount of radiant energy of allwavelengths which can be emitted by a body at a giventemperature. SP-7 1968Black Hawk assault helicopterUse H-60 Helicopterblade slap noiseImpulsive noise (short high pressure sound waves) of rotatingblades primarily helicopter blades. Used for helicopter impulsivenoise. 1981bladesArms of propeller and rotating wings. Specifically, restrictive, thoseparts of propellers or of rotat ing wings from the shank outward,i.e. those parts having efficient airfoil shapes and that cleave theair. Vanes such as rotating vanes or stationary vanes in rotary aircompressors, or vanes of turbine wheels. SP-7 1968blankets (fission reactors)Damper materials for fission reactors.blankets (fusion reactors)Damper materials for fusion reactors.

1979

1979blast deflectorsDevices used to divert the exhaust of a rocket fired from a verticalposition. SP-7 1968bloediteA mineral consisting of hydrous sodium mangnesium sulfate thatis colorless. Also known as astrakanite or astrochanite. 1978blood-brain barrierA mechanism which maintains the constancy of the neurons inthe central nervous system by preventing certain substances fromleaving the bloodstream and entering the neural tissue. 1980blue starsStars of spectral type 0, B, A, or F according to the Draper

bluff bodiesBodies having a broad, flattened front, as in some rentry vehicles.

catalog. f981

SP-7 1968blunt leading edgesThe obtuse cross sections of certain front edges of airfoils orwings. 1976blunt trailing edgesThe rounded or obtuse angled trailing edges of wings and/orcontrol surfaces designed to enhance aerodynamiccharacteristics. 1979boattallsThe rear portions of elongated bodies, as in rockets, havingdecreasing cross-sectional area toward the rear. SP-7 1968BODUse biochemical oxygen demandbodies of revolutionSymmetrical bodies having the form described by rotating a planecurve about an axis in its plane. SP-7 1968

body temperature (non-biological)Use temperaturebody temperature regulationUse thermoregulationBoeing 757 aircraftBoeings twin turbofan short/medium range transport aircraft thatmade its first flight on February 19, 1982. 19g90Boeing 767 aircraftBoeings widebodied medium range commercial transport aircraft1980hat made its first flight on September 26, 1981.bogsUse marshlandsBohr magnetonA constant equivalent to the magnetic moment of an electron.

SP-7 7970bolidesBrilliant meteors, especially ones which explode; detonatingfireballs. SP-7 1968bologramsUse bolometersbolometersInstruments which measure the intensity of radiant energy byemploying thermally sensitive electrical resistors; a type ofactinometer. Used for bolograms. SP-7 19178bolted jointsJoints fastened with bolts. They are usually designed for heavyloads. 1987bombs (ordnance)Explosive devices designed to be detonated under specifiedconditions. DOE 1968bondingSpecifically, a system of connections between all metal parts iofan aircraft or other structure forming a continuous electrical unitand preventing jumping or arching of static electricity. Glueing o rsementing together for structural strength. SP-7 1968Bonne projectionA type of conical map projection in which meridians are plottedas curves and the parallels are spaced along them at truedistances. 1980Boolean algebraThe study of the manipulation of symbols representing operationsaccording to the rules of logic. Boolean algebra corresponds toan algebra using only the numbers 0 and 1, therefore can beused in programming digital computers which operate on the binaryprinciple. SP-7 1968boostUse acceleration (physics)boostglide vehiclesVehicles designed to glide in the atmosphere following arocket-poweredphase. Portions of the flights may be ballistic, outof the atmosphere. SP-7 1968



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BOREHOLES

boreholesHoles made by drilling into the ground to study stratification, tosearch for or to obtain natural resources, or to release undergroundpressures. 1980boresight errorLinear displacement between two parallel lines of sight.boron fibersFibers produced by vapor deposition methods; used in variouscomposite materials to impart a balance of strength and stiffness.1979

1980

borosilicate glassLow expansion heat resistant glass. Used for Pyrex (trademark).DOE 1968Borsic (tradename)Trademark of United Aircraft Products, Inc. for its boron aluminumcomposite materials. 1980Bouguer lawA relationship describing the rate of decrease of flux density of aplane-parallel beam of monochromatic radiation as it penetrates amedium which both scatters and absorbs at that wavelength.Used for Lambert law. SP-7 1968boundary element methodTechnique for solving two-and three-dimensional boundary valueproblems in thermodynamics, mechanics, etc. 1981boundary integral methodTechnique related to the boundary element method, and used forlaminar and turbulent flow problems. 1981boundary layer plasmasPlasmas resulting from the frictional heat of hypersonic spacecraftentering the earths atmosphere. 1976boundary value problemsPhysical problems completely specified by a differential equationin an unknown, valid in a certain region of space, and certaininformation (boundary condition) about the unknown, given on theboundaries of that region. The information required to determinethe solution depends completely and uniquely on the particularproblem. Used for initial value problems and point matching method(mathematics). SP-7 1968Boussinesq approximationThe assumption (frequently used in the theory of convection) thatthe fluid is incompressible except insofar as the thermal expansionproduces a buoyancy. SP-7 1968bow shock wavesUse bow waves

shock waves

bow wavesShock waves in front of a body, such as an airfoil, or apparentlyattached to the forward tip of the body. Used for bow shockwaves. SP-7 1968Bragg angleThe angle between the incident beam and the lattice planesconsidered. ASTM (E 7, E-4) 1968

16

Bragg curveA curve showing the average specific ionization of an ionizingparticle of a particular kind as a function of its kinetic energy,velocity, or residual range. 1981brailleA system of writing that uses characters made up of raised dots.It was named after Louis Braille. 1981Brayton cycleA thermodynamic cycle consisting of two constant-pressureprocesses interspersed with two constant-antropy cycles. Namedafter George B. Brayton, American engineer. DOE I968Brazilian space programThe space program of Brazil which is under the jurisdiction of thelnstituto de Pesquisas Espaciais (INPE). 1982breadboard modelsAssemblies of preliminary circuits or parts used t o prove t hefeasibility of a device, circuit, system, or principle without regardto the final configuration or packaging of the parts. SP-7 1968bremsstrahlungElectromagnetic radiation produced by the rapid change in thevelocity of an electron or another fast, charged particle as itapproaches an atomic nucleus and is deflected by it. In Germanit means braking radiation. SP-7 1968bricksSolid masonry units of clay or shale, usually formed into arectangular prism while plastic and burned or fired in a kiln. Bricksare ceramic products. ASTM (C 43, C-15) 1968brightnessThe attribute of visual perception in accordance with which anarea appears to emit more or less light. SP-7 1968brightness distributionThe statistical distribution based on brightness, or the distributionof brightness over the surface of an object. 1981brightness temperatureIn astrophysics, the temperature of a black body radiating thesame amount of energy per unit area at the wavelengths underconsideration as the observed body. The temperature of a nonblackbody determined by measurement with an optical pyrometer.SP-7 1970brinesWater saturated or strongly impregnated with common salt.

DOE 1968broken symmetryPhenomena where a loss of symmetry is present such as inpiezoelectricity. Used for symmetry breaking. 1981Brunt-Vaisala frequencyThe frequency at which an air parcel will oscillate when subjectedto an infinitesimal peturbation in a stably stratified atmosphere.

1983brushes (electrical contacts)Conductive metal or carbon blocks used to make sliding electricalcontact with a moving part as in an electric motor. 1976

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CAPSULES (SPACECRAFT)

bubblesInternal voids or trapped globules of air or other gas.ASTM (C 582, C-3) 1968

bucklingAn unstable state of equilibrium of a thin-walled body stemmingfrom compressive stresses in walls. The lateral deflection of athin-walled body resulting from such instability. SP-7 1968buffer storageIn computer operations, storage used to compensate for adifference in rate of flow or time of occurence when transferringinformation from one device to another. SP-7 1968buffetingThe beating of an aerodynamic structure or surfaces by unsteadyflow, gusts, etc.; the irregular shaking or oscillation of a vehiclecomponent owing to turbulent air or separated flow. SP-7 1968building structuresUse buildingsbuildingsStructures erected and framed of component structural membersdesigned for the housing, shelter or support of persons, animals,or property. Used for building structures.ASTM (E 683, E-44) 968bulk acoustic wave devicesAcoustooptic devices utilizing bulk sound waves at megahertzfrequencies in thin fi lm transducers. Used for B-A-W devices.1979bulk modulusThe reciprocal of the coefficient of compressibility.bulkheadsSteep or vertical structures supporting natural or artificial

SP-7 1968

embankments. ASTM (A 700, A-1) 1968bumpy torusesThe shapes (doughnuts) of certain plasmas.burningUse combustionburning processUse combustionburning rateThe velocity at which a solid propellant in a rocket is consumed.

burnoutThe termination of combustion in a rocket engine because of

butylene oxidesUse tetrahydrofuranbypass ratioRatio of the secondary to the primary inlet airflows for a turbofanengine. 1981

1980

The symbol is r. SP-7 1968

exhaustion of the propellant. 1968

C

C-8A augmentor wing aircraftNASA's research, short haul, jet aircraft. 1.977CAD (design)Use computer aided designcadmium mercury telluridesUse mercury cadmium telluridescalderasLarge, basin-shaped volcanic depressions, more or less circular inform, the diameter of which is many times greater than that ofthe included vent or vents. DOE 1.971calendarsOrderly arrangements of days, weeks, months, etc. to suit aparticular need such as civil life. SP-7 1.969CallistoA satellite of Jupiter orbiting at a mean distance of 1,884,000kilometers. Also called Jupiter IV . SP-7 1876calorimetersInstruments designed to measure heat evolved or absorbed. Usedfor microcalorimeters. SP-7 1968CAM (manufacturing)Use computer aided manufacturingCanadian space programSpace research, programs, and activities undertaken by Canada.7.980Canadian spacecraftSpacecraft of the Canadian Government. The following satelliteshave been developed: Alouette satellites, lSlS satellites, A.niksatellites, and Hermes satellite. RADARSAT and MSAT are in theprocess of being developed. 1?83canard configurationsPertaining to an aerodynamic vehicle in which horizontal surfacesused for trim and control are forward of the main lifting surface;the horizontal trim and control surfaces in such an arrangement.

. SP-7 1!?68canopies (vegetation)The topmost layers of leaves and branches of forest trees orother plants. 1.980capacitanceThat property of a system of conductors and dielectrics whichpermits the storage of electrically seperated charges when potentialdifferences exist between the conductors. It is the ratio of a quantity,Q, of electricity to a potential difference, V. A capacitance valueis always positive. The units are farads when the charge isexpressed in coulombs and the potential in volts: C = Q/V.Capacitance is symbolized as C.ASTM (D 150, D 1711; 0-4) 1968capacitance-voltage characteristicsThe characteristics of a metal semiconductor contact or asemiconductor junction that manifests a measured capacitance asa function of a dc bias voltage with small, superimposed ac voltageapplied to that junction or contact. 1985capsules (spacecraft)Use space capsules

C-M diagramUse color-magnitude diagram



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CAPTIVE TESTS

captive testsHolddown tests of a propulsive subsystem, rocket engine or motoras distinguished from a flight test. SP-7 1968capture cross sectionsUse absorption cross sectionscapture effectAn effect in frequency-modulation (FM) reception where thestronger signal of two stations on the same frequency completelysurpresses the weaker signal. SP-7 1968carbenesAn organic radical containing divalent carbon.carbidesCompounds 0:carbon with one or more metallic elements.

DOE 1968

SP-7 1968carbon cycleThe path of carbon in living beings in which carbon dioxide isfixed by photosynthesis to form organic nutrients and ultimatelyrestored to the inorganic state by respiration and protoplasmicdecay. 1980carbon suboxidesColorless lacrimatory gases having unpleasant odors and boilingpoints of approximately -7 degrees C. 1977carbonaceous materialsSubstance composed of or containing carbon or carboncompounds. 1978carburizingIntroducing carbon into a solid ferrous alloy by holding above A c lin contact with a suitable carbonaceous material. The carborizedalloy is usually quench hardened. ASTM (E 44, E-4) 1968carcinogensAgents producing or inciting cancerous growth.ASTM (E 609, E-35) 1968cardiovascular systemThe system of an animal pertaining to the heart and blood vessels.Used for vascular system. SP-7 1968Caribbean regionThe region that consists of all or parts of the islands of theCaribbean Sea, the Bahamas, the British dependent territories,the Virgin Islands, and the mainland areas of the three Guianasand Belize. 1984Carnot cycleAn idealized reversible thermodynamic cycle. The carnot cycleconsists of four stages: (a) an isothermal expansion of the gas attemperature T I ; (b) an adibiatic expansion to temperature T2; (c)an isothermal compression at temperature T2; (d) an adiabaticcompression to the original state of the gas to complete thecycle. SP-7 1968carrier density (solid state)semiconductor which determines its electronic characteristics andThe charge carrier concentrations of holes and/or electrons in afunction. 1979carrier modulationUse modulation

carrier to noise ratiosRF signal power input to the receiver divided by the noise powerinput. 1981carrier transport (solid state)The mobility of conduction electrons or holes in semiconductors.1980carrier wavesWaves generated at a point in the transmitting system andmodulated by the signal. Used for subcarrier waves. SP-7 1968Cartesian coordinatesA coordinate system in which the locations of points in space areexpressed by reference to three planes, called coordinate planes,no two of which are parallel. Used for rectangular coordinates.SP-7 1968cartridge actuated devicesUse actuatorscatapultsA power-actuated machine or device for hurling forth something,as an airplane or missile, at a high initial speed; also a deviceusually explosive, for ejecting a person from an aircraft.SP-7 1968cathode ray tubesVacuum tubes consisting essentially of an electron gun producinga concentrated electron beam (or cathode ray) which impingeson a phosphorescent coating on the back of a viewing face (orscreen). The excitation of the phosphor produces light, the intensityof which is controlled by the flow of electrons. Deflection of thebeam is achieved either electromagnetically by currents in coilsaround the tube, or electrostatica lly by voltages on internaldeflection plates. SP-7 1968cathodesIn electron tubes, electrodes through which a primary stream ofelectrons enters the interelectrode space. SP-7 1968cathodic coatingsMaterial forming a continuous film on a base metal by mechanicalcoating or by electroplating. 1980cathodoluminescenceLuminescence produced when high velocity electrons bombard ametal in a vacuum, thus vaporizing small amounts of the metalwhich, in an excited state, emit radiation characteristic of themetal. 1985

cationsPositively-charged ons.CATT devicesControlled avalanche transit time triodes which use avalanchemultiplication in the collector depletion region of a silicon, bipolar,transistor-like structure to increase the gain and thereby achievea higher frequency operation of silicon bipolar transistos. Used forcontrolled avalanche transit time devices. 1981

ASTM (B 374, B-8; G 15,G- 1) 1968

caulkingMaterial ranging in physical characteristics from plastic to solid topreformed. Used to seal and waterproof joints and overlaps instructures, other assemblies or portions thereof where movementmay occur. ASTM (C460, C-17) 1968



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CERMETS

caustic linesThe locations of wave front interactions induced by the maneuversof supersonic aircraft in changing direction and/or attitude. 1980

caustics (optics)The envelope of rays diffracted by surface defects in materials.7980cavitationUse cavitation flowcavitation flowThe formation of bubbles in a liquid, occurring whenever the staticpressure at any point in the fluid flow becomes less than the fluidvapor pressure. Used for cavitation and gaseous cavitation.SP-7 1968cavitonsDensity cavities created by localized oscillating electric fields.1982CCDUse charge coupled devicesCCD star trackerNavigation instrument designed for the NASA space transportationsystem. Used for stellar (star tracker).CDMAUse code division multiple accesscelestial bodiesAny aggregations of matter in space constituting a unit forastronomical study, as the sun, moon, a planet, comet, star, or

1977

nebula. Also called heavenly bodies. SP-7 1968celestial geodesyThe determination of the form of the earth, of the earth'sgravitational field, and of relative positions of satellite trajectories.

7968celestial mechanicsThe study of the theory of motions of celestial bodies under theinfluence of gravitational fields. SP-7 1968celestial navigationThe process of directing a craft from one point to another byreference to celestial bodies of known constants. SP-7 1968celestial observationUse astronomycelestial sphereAn imaginary sphere of infinite radius concentric with the earth,on which all celestial bodies except the earth are assumed to beprojected. SP-7 1968celluloseThe carbohydrate that is the principal constituent of wood andforms of structural framework of the wood cells.

ASTM (D 9, 0-7) 1968cementiteAn intermetallic compound containing iron and carbon. DO 1968center of gravityThe center of mass of a system of masses, as the barycenter ofthe earth-moon system. Used for barycenter. SP-7 1968

center of massA point of a material body or system of bodies which moves asthough the system's total mass existed at that point and all externalforces were applied at the point. 19j78centimeter wavesElectromagnetic radiation in the 3,000 to 30,000 MHz range. 19j77centrifugal forceThe apparent force in a rotating system, deflecting masses radiallySP-7 1968rom the axis or rotation.centrifugesSpecifically in aerospace, large motor driven apparatus with longarms at the end of which human and animal subjects or equipmentcan be revolved and rotated at various speeds to simulate (veryclosely) the (prolonged) accelerations in high performance aircraft,rockets, and spacecraft. Sometimes called astronautic centrifuges.Used for cyclones (equipment). SP-7 1968

cepstraThe Fourier transformation of the logarithm of the powerspectrum. 1976cepstral analysisThe application of cepstral methods to wave or signal phenomeriain seismology, speech analysis, echos, underwater acoustics, etc:.1976ceramal protective coatingsUse cermetsceramalsUse cermetsceramic fibersFibers composed of ceramic materials. They are usually used forreinforcement. 1965ceramic matrix compositesComposite materials consisting of a reinforced ceramic matrix.1963ceramicsInorganic compounds or mixtures requiring heat treatment to fusethem into homogeneous masses usually posessing hightemperature strength but low ductility. Types and uses range fromchina for dishes to refractory liners for nozzles. SP-7 1968Cerenkov effectUse Cerenkov radiationCerenkov radiationThe radiation from a charged particle whose velocity is greaterthan th phase velocity that an electromagnetic wave would haveif it were propagating in the medium. The particle will continue tolose energy by radiation until its velocity is less than this phasevelocity. Used for Cerenkov effect. SP-7 1968cermetsBodies consisting of ceramic particles bonded with a metal; usedin aircraft, rockets, and spacecraft for high strength, hightemperature applications. The name is derived from a combinationof CERamic and METal. Used for ceramal protective coatingsand ceramals. SP-7 1968



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CESSNA 4028 AIRCRAFT

Cessna 4028 aircraftA lighter, twin-engine, short-haul cargo/passenger aircraftmanufactured by the Cessna Aircraft Company. 1976CFDUse charge flow devicesChandler motionUse polar wandering (geology)change detectionA process of examining imagery to detect changes on a planetarysurface or astronomical body. 1984channel noiseIn communications bursts of interruptive pulses caused mainly bycontact closures in electromagnetic equipment or by transientvoltages in electric cables during transmission of signals or data.Impulsive noise is the frequent cause of transmission errors. 1980Chapman-Jouget flameUse detonationcharacteristicsSpecifically, distinguishing qualities, properties, features orcapabilities of an entity. SP-7 1968charge coupled devicesSemiconductor devices arrayed so that the electric charge at theoutput of one provides the input stimulus to the next. Use forCCD. DOE 1974charge efficiencyThe efficiency d electric cell recharging. 1980charge exchangeThe collisional transfer of an electron from a neutral atom ormolecule to an ion. 1968charge flow devicesMetal oxide semiconductor (MOS) devices used for fire detectorsand humidity sensors. Used for CFD. 1978charm (particle physics)A quantum number which has been proposed to account for anapparent lack of symmetry in the behavior of hadrons relative tothat of leptons, to explain why certain reactions of elementaryparticles do not occur, and to account for the longevity of the Jparticle. 1981CharonNatural satellite of the planet Pluto, discovered and named by Dr.James W. Christy. 1979checkoutA sequence of actions taken to test or examine a thing as to itsreadiness for incorporation into a new phase of use, or for theperformance of its intended function. The sequence of steps takento familiarize a person with the operation of an airplane or otherpiece of equipment. Used for debugging. SP-7 1968chemical cloudsArtifical clouds of chemical compounds released in the ionospherefor observation of dispersion and other characteristics. 1978chemical defenseAll actions and counteractions designed for the protection ofpersonnel and material against offensive chemical agents. 1980

20

chemical energyEnergy produced or absorbed in the process of a chemical reaction.In any such a reaction, energy losses or gains usually involveonly the outermost electrons of the the atoms or ions of thesystem undergoing change; here a chemical bond of some typeis established or broken without disrupting the original atomic orionic identities of the constituents. SP-7 1968chemical evolutionThe theory of the creation or production of living matter fromnonliving matter. 1976chemical fuelsFuels that depend upon an oxidizer for combustion or fordevelopement of thrust, such as liquid or solid rocket fuel or internalcombustion engine fuel: distinguished from nuclear fuel.SP-7 1969chemical release modulesShuttle launched, free-flying spacecraft containing canisters forinjecting chemicals into the upper atmosphere and themeasurement of the reactions. 1980chemiluminescenceAny luminescence produced by chemical action. SP-7 1968chemisorptionThe binding of a liquid or gas on the surface or in the interior ofa solid by chemical bonds or forces.chemosphereThe vaguely defined region of the upper atmosphere in whichphotochemical reactions take place. It is generally considered toinclude the stratosphere (or the top thereof) and the mesosphere,and sometimes the lower part of the thermosphere. SP-7 1968

SP-7 1968

Chinese spacecraftSatellites built and launched by the Chinese Peoples Republic.1980chips (electronics)Integrated microcircuits mounted on substrates and performingsignificant numbers of functions. 1977chips (memory devices)Integrated microcircuit devices used collectively to perform thefunctions of data storage: accepting, retaining, and emitting bitsof data. 1977ChironMinor planet 2060, a solar system asteriod discovered by CharlesT. Kowal of Hale Observatories. Used for Minor Planet 2060.1980chirpAn all encompassing term for the various techniques of pulseexpansion-pulse compression applied to pulse radar; a techniqueto expand narrow pulses to wide pulses for transmission, andcompress wide received pulses to the original narrow pulse widthand wave shape, to gain improvement in signal-to-noise ratiowithout degradation to range resolution and range discrimination.

SP-7 1968chitinA polysaccharide which is the principal constituent of the shellsof crabs and lobsters and of the shards of beetles. It is alsofound in certain fungi. 1968

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NASA Thesaurus - Volume 3 - Definitions