EP - 107 Skylab: A Guidebook

 

[237-243] CHAPTER XI: Glossary

 

 

ABLATION - The removal of surface material from a body by vaporization, melting chipping, or other erosive process; specifically, the intentional removal of surface matter from a reentry body during high-speed movement through a planetary atmosphere to protect the remaining body from the heat generated by friction.
 
ABSORPTIVITY - A property of a material, characterizing its capability to absorb rather than transmit or reflect incident radiant energy.
 
ALBEDO - Relative brightness of a surface or region, measured as the ratio of the amount of reflected radiation to the amount of incident radiation.
 
ALDOSTERONE - The principal electrolyte-regulating steroid secreted by the adrenal complex (steroid is a group name for compounds that resemble cholesterol chemically). Some of the substances in this group include sex hormones and bile acids.
 
ALPHA PARTICLE - The positively charged nucleus of a helium atom. Each alpha particle consists of two protons and two neutrons. Alpha particles are emitted by some of the radioactive substances, they are also found in cosmic radiation.
 
ALTIMETER - An instrument that determines height above a reference level, commonly by measuring the change of atmospheric pressure, or by measuring vertical distance directly with a radar-type system.
 
ANGIOTENSIN - A vessel-constricting substance present in the blood, and formed by the action of renin (enzyme involved in changing proteins into other products) on a globulin (a class of proteins characterized by being insoluble in water, but soluble in saline solutions ) .
 
ANGSTROM UNIT - Unit of length employed to measure wave lengths of light. One Angstrom unit is one ten-thousandth of a micrometer or one ten-billionth of a meter. Ten Angstrom units make one nanometer.
 
ANTIBODY - A substance produced by the body in response to the introduction of a foreign substance (antigen).
 
ANTIDIURETIC HORMONE (vasopressin) - A hormone that suppresses the secretion of urine. Vasopressin also stimulates the contraction of the muscular tissue of the capillaries and arterioles.
 
ANTIGEN - A substance which, when introduced into the body, stimulates the production of antibodies. Bacteria, their toxins, red blood corpuscles, tissue extracts, pollens, dust, and many other substances may act as antigens.
 
APOGEE - That point on the trajectory of an Earth - orbiting body which is most distant from the Earth. Also used in connection with orbits of celestial bodies around other celestial bodies.
 
BALMER SERIES - The visible line spectrum emitted by hydrogen. The wavelengths of the lines form a series, the formula of which was established by Balmer ( 1885 ).
 
BANDPASS FILTER - A wave filter that has a single transmission band extending from a lower cutoff frequency greater than zero to a finite upper cutoff frequency.
 
BIOASSAY - Estimation of the active power of a sample of a drug, or of other agents or influences, by noting their effects on animals or man.
 
BLOOD PLASMA - The liquid component of the blood in which the corpuscles are suspended. Plasma may be obtained from whole blood by removing the corpuscles by centrifuging or by sedimentation. It contains all the chemical constituents of whole blood except hemoglobin.
 
BORESIGHTING - A process of parallel alignment of the lines of sight of two instruments by an optical procedure.
 
CARDIOTACHOMETER - An instrument for counting or recording the heart beats over long periods of time.
 
CARDIOVASCULAR - Heart and vessel system.
 
CHROMOSPHERE - Layer of the solar atmosphere about 14,000 km (8000 naut. ml.) thick, which surrounds the Sun's visible surface (photosphere). It is best observable during an eclipse or other occultation of the solar disc.
 
CIRCADIAN RHYTHM - A rhythm with a period of about 24 hours, applied especially to the rhythmic repetition of certain phenomena in living organisms at about the same time each day.
 
CONTROL MOMENT GYROSCOPE - A large and heavy gyroscope suspended by a two axis gimbal system. The outer gimbal axis is connected with the spacecraft through a torque motor, the inner axis is free to precess. By energizing the torque motor the spacecraft attitude can be controlled.
 
CONVECTION - Mass motions with a fluid (liquid or gas) resulting in transport and mixing of the components of that fluid. Thermal convection results from temperature differences within the fluid.
 
CORONA - The tenuous envelope of the Sun, beginning about 14,000 km (8000 naut. mi. ) above the solar surface and extending many millions of kilometers into space. The corona is visible only when the solar disc is occulted.
 
CRAWLER - A large tracked vehicle also called Transporter. It is similar to machines used in strip mining operations. The vehicle moves on four double tracks and transports the Saturn V with the Skylab and mobile launcher, and also the Saturn lB, from the Vertical Assembly Building to the launch pad at the Kennedy Space Center.
 
CYTOGENETICS - The branch of genetics devoted to the study of the cellular constituents which are concerned with heredity (chromosomes and genes). Also, the scientific study of the relationship between chromosomal aberrations and pathological conditions.
 
DECIBEL - The decibel is a ratio of two numbers, equal to the tenth root of ten or about 1.259. It is mostly used as the ratio of two power levels. If a radio receiver, playing at a certain "volume" level. is turned up until the acoustic power output has increased by 25.9%, its new level is one decibel above the original level.
 
DEGREES K - Degrees Kelvin. A degree of temperature on the Kelvin scale also called '`absolute scale." The Kelvin zero point is approximately -273.1° Centigrade. A degree Kelvin is equal in magnitude to a degree on the Centigrade scale.
 
DEHYDROGENASE - An enzyme which mobilizes the hydrogen of a substrate (the base on which an organism lives) so that it can pass to a hydrogen acceptor.
 
DESSICANT - A drying agent.
 
DICHROIC - The property of a substance to appear in one color by reflected light and in another by transmitted light.
 
DIFFUSION - In an atmosphere, as in any gaseous system, the exchange of fluid parcels between regions, in apparently random motions of a scale too small to be treated by the equations of motion.
 
DNA - Deoxyribonucleic acid, a complex organic acid of high molecular weight consisting of chains of alternate units of phosphate and a pentose sugar (a sugar having five oxygen atoms) which has a purine and pyrimidine base attached to it. In DNA the sugar is 2-deoxyribose. DNA is believed to carry all the hereditary traits of a species coded in the sequence of atomic groups along its length. See RNA.
 
DOSIMETER - An instrument for measuring the accumulated flux of particle or photon radiations, such as protons in the Van Allen Belts, or X - rays in solar radiation.
 
ELECTROCARDIOGRAM - A written or printed record of the heart's action, made by an electrocardiograph, an instrument for recording the changes of electrical potential occurring during the heartbeat.
 
ELECTROLYTE - A solution which conducts electricity. Passage of current is accompanied by liberation or consumption of matter at the electrodes. Also, a substance, as an acid, base, or salt, that becomes such a conductor when dissolved in a suitable solvent, or fused. The current is carried by charged particles (ions).
 
ELECTROPHORESIS - The movement of molecules or other very small particles through a fluid under the action of an external electric field. Positively charged particles (metallic oxides, basic dyestuffs) migrate to the cathode, and negatively charged particles (metals, sulfur, metallic sulfides, acid dyestuffs) migrate to' the anode.
 
EMISSIVITY - A property of a material, characterizing its capability to emit electromagnetic radiation as a consequence of its inherent thermal energy.
 
ENDOCRINE GLAND - A ductless gland whose secretions pass directly into the lymph or blood stream. These glands produce hormones which control action and development of other parts of the body either by activation or by inhibition.
 
ENZYME - An organic compound, frequently a protein, capable of accelerating or producing by catalytic action some change in an organic substance for which it is often specific. An activating enzyme activates a given amino acid by attaching it to the corresponding transfer ribonucleic acid.
 
EPHEMERIS - Periodical publication which lists the predicted positions of celestial bodies at regular intervals, and the times of astronomical occurrences. It also contains other data of interest to astronomers.
 
EPINEPHRINE CONCENTRATIONS - Concentrations of adrenaline (compound occuring naturally as the adrenal hormone). In certain concentrations the compound causes an increase in blood pressure and in the sugar content of the blood.
 
ERGOMETER - A device for measuring energy expended or work done.
 
EUTECTIC - In certain ranges of metal alloys there is one is mixture which melts at a lower temperature than any other alloy in the series. Such an alloy is termed the eutectic.
 
EXOTHERMIC - A process which releases rather than absorbs, heat energy.
 
FABRY-PEROT INTERFEROMETER - An instrument utilizing the wave nature of light to cause constructive or destructive interference of light by passing a light beam between two parallel partially reflecting surfaces.
 
FIBRIN - A whitish, insoluble protein which forms the essential portion of the blood clot.
 
FIBRINOLYSIS - The splitting Up of fibrin by enzyme action.
 
FIBRINOLYTIC - Pertaining to, characterized by. or causing fibrinolysis.
 
FILAMENT - In solar physics, filament designates a quiet prominence or plasma cloud high above the chromosphere, visible as a dark narrow patch against the bright solar disc.
 
FLARE - A violent eruption on the Sun's surface (chromosphere), accompanied by emissions of protons and other particles and of electromagnetic radiation.
 
FRAUNHOFER LINES - Dark lines in the spectrum of solar radiation. produced by the absorption of light by gases in the outer portions of the Sun.
 
GEGENSCHEIN - A faint light observed from the dark side of the Earth in a direction opposite to the Sun. It results from sunlight reflected by dust particles which orbit the Sun at planetary distances.
 
GEOCORONA - That region around the Earth which extends from a height of about 600 km (330 naut. mi.) to about 3000 km (1700 naut. mi.). It consists mainly of helium in the lower regions, and of hydrogen in the upper regions.
 
GIMBAL - A ring or frame with two mutually perpendicular and intersecting axes of rotation, providing free angular movement in two directions, on which a rocket engine, or a gyroscope or another instrument may be mounted.
 
GLUCOSE - - Chemical name for a natural sugar found in fruits and in the blood.
 
GLUTATHIONE - Co - enzyme of glyoxalase which acts as a respiratory carrier of oxygen.
 
GLYCERALDEHYDE - A compound formed by the oxidation of glycerol, a mixture of glycerin and acetanilid powder.
 
GRANULATION - A net - like pattern of irregular cells on the solar surface, visible in white light. The cells are caused by plasma convection within the photosphere. Cell diameters are 800 km (450 naut. mi.) to 3000 km (1700 naut. mi.); each individual cell has a lifetime of several minutes.
 
GREENWICH MEAN TIME - Mean solar time at the Greenwich meridan, used by most navigators, and adopted as the prime basis of standard time throughout the world.
 
GROUND TRUTH - Definition of Earth surface conditions through direct measurements or visual inspections for calibration or evaluation of remote sensing observations made from satellites or aircraft.

HEMATOCRIT - An instrument for determining the relative amounts of plasma and corpuscles in blood, generally some form of centrifugal apparatus.

 
HEMATOLOGY - A branch of medicine concerning the study of the blood, the bloodforming tissues, and the diseases of the blood.
 
HEMOLYSIS - The dissolution of red blood corpuscles with liberation of their hemoglobin, an iron-containing protein respiratory pigment occurring in the red blood cells.
 
HEXOKINASE - An enzyme that catalyzes the transfer of a high-energy phosphate group of a donor to D-glucose, producing D-glucose-6-phosphate.
 
HUMORAL - Pertaining to fluid or semifluid substances in the body.
 
IMMUNOLOGY - The medical, bacteriological, and chemical study of the phenomena and causes of immunity.
 
IONOSPHERE - Region of ionized gases surrounding the Earth and extending from about 60 km (33 naut. mi) to distances up to several hundred kilometers. The ionization in this region is due to bombardment by ultraviolet radiation and X - rays from the Sun, and by cosmic rays. The existence of this region makes possible longrange radio communications through reflection of terrestrial radio transmission.
 
ISOTOPE - Isotopes of an element have the same number of protons in their nuclei, and hence represent the same element, but they differ in the number of neutrons and therefore in mass number.
 
KINASE - An organic substance (enzyme) which activates other substances to develop into chemical ferments or enzymes.
 
LEUKOCYTE - White blood corpuscle.
 
LIMB - The outer edge or a portion of the edge of a celestial body such as the Moon, Venus, or the Sun, as seen from a distance.
 
LYIDE (Lipid) - A fatty acid insoluble in water.
 
LYMAN CONTINUUM - The ultraviolet region of the spectrum of the hydrogen atom immediately adjacent to the Lyman line spectrum with wavelengths shorter than 912 Å.
 
LYMPHOCYTE - Lymph cell or white blood corpuscle without cytoplasmic granules.
 
MAGNETOSPHERE - The region around the Earth above about 160 km (90 naut. mi.) and below the magnetopause (about 15 earth radii in the solar direction, and at least 40 earth radii in the antisolar direction ) . Inside the magnetosphere, the Earth's magnetic field is dominant; outside, the interplanetary magnetic field dominates.
 
MASS SPECTROMETER - An instrument which determines the masses of atoms and molecules.
 
METABOLIC CHANGES - The sum of all physical and chemical changes which take place within an organism; all energy and material transformations which occur within living cells.
 
METABOLISM - The interchange of materials between living organisms and the environment, or within a living organism, by which energy for maintaining life is secured.
 
METAPHASE - The stage during cell division in which the chromosomes are arranged in an equatorial plate.
 
METEOR - The light resulting from the transition of a solid particle (meteoroid) from space through the Earth's atmosphere, commonly called a "shooting star" or "falling star."
 
METEORITE - A solid particle from space which enters the Earth's atmosphere and reaches the surface. Meteorites are classified as iron meteorites (siderites) and stone meteorites (aerolites) according to their compositions.
 
METEOROID - A solid object moving through interplanetary space of a size considerably smaller than an asteroid and considerably larger than an atom or molecule. When the object glows while traveling through the Earth's atmosphere, it is called a meteor; when it reaches the surface of the Earth, it is called a meteorite.
 
METHEMOGLOBIN - A soluble brownish-red, crystalline compound from which the oxygen cannot be removed in a vacuum. It is formed by the spontaneous decomposition of blood, and also by the action on blood of various oxidizing reagents, as oxone, etc.
 
MICRON - A unit of length equal to one - millionth of a meter or one - thousandth of a millimeter, usually called micrometer.
 
MORPHOLOGY - Branch of biology dealing with the form and structure of animals and plants. It includes anatomy, histology and organography, and also the nonphysiological aspects of cytology and embryology.
 
MULTISPECTRAL - Utilizing radiation from several discrete bands of the spectrum simultaneously.
 
NADIR - The direction vertically downward (opposite to zenith)
 
NANOMETER - One - billionth of a meter (10-9 meter).
 
NOREPINEPHRINE - A hormone secreted by the adrenal medulla in response to stimulation in the viscera, and stored in granules that stain strongly with chromium salts. Granules are released predominantly in response to hypotension (diminished tension or lower blood pressure).
 
OCCULTATION - The disappearance of a celestial body behind another body of equal or larger apparent size, such as the occultation of the Sun by the Moon as viewed by an Earth observer during a solar eclipse. Also, the covering of the image of a celestial body by a disc whose size is equal to or larger than the size of the image.
 
OCULOGYRAL ILLUSION - An illusion developed by the movement of the eye about an axis from the front to the rear of the head.
 
ORTHOSTATIC - The upright, or erect, position of the human body.
 
OSMOLALITY - The property of a liquid to exercise an osmotic pressure because it contains an electrolyte in solution.
 
OUTGASSING - The emanation of gas from a material. This process is usually enhanced in vacuum.
 
PERIGEE - That point on the trajectory of an orbiting body which is nearest the Earth when the Earth is the center of attraction. Also, used in connection with orbits of celestial bodies around other celestial bodies.
 
PHOTOMETER - An instrument for measuring the intensity of light by comparing it with a standard.
 
PHOTOMULTIPLIER TUBE - An electron tube that produces electrical signals in response to light. In the tube, the electric signal is amplified to produce a measurable output signal even from very small quantities of light.
 
PHOTOSPHERE - Intensely luminous surface layer of the Sun in which the sunspots and several other solar phenomena occur.
 
PLAGES - Bright regions in the chromosphere of the Sun, usually near sunspots, indicating areas of enhanced magnetic field strength (10 to 100 Gauss*) and increased solar activity. Plages are best observed in monochromatic light of hydrogen or calcium.
 
PLASMA - A gas composed of ions, electrons, neutral atoms, and molecules. The interactions between particles of a plasma are mainly electromagnetic. Although many of the individual particles are electrically positive or negative, the plasma as a whole is neutral.
 
PLASMA RENIN - Plasma is the fluid portion of the blood in which the corpuscles are suspended. Renin is an enzyme involved in changing proteins into other products.
 
PLETHYSMOGRAPH - An instrument for determining and registering variations in the size of an organ part or limb, and in the amount of blood present or passing through it.
 
POLARIMETER - An instrument for determining the degree of polarization of electromagnetic radiation, specifically the polarization of light.
 
POLARIZATION - The state of electromagnetic radiation when the transverse oscillations take place in some regular manner, e.g., all in one plane.
 
PRECESSION - The angular motion (tilting) of the axis of a spinning or rotating body caused by a torque whose axis is not parallel with the axis of rotation.
 
PRINCIPAL INVESTIGATOR - The researcher responsible for defining an investigation or experiment as part of a NASA science or technology project, and for ensuring that the investigation of the experiment meets with its specific objectives.
 
PROMINENCE - A plasma protuberance above the surface of the Sun, originating in the chromosphere and extending sometimes to a height of several hundred thousand kilometers.
 
PROTON - Positively-charged nuclear particle which forms a significant part of all atomic nuclei. The nucleus of a normal hydrogen atom is a proton. It is 1,837 times heavier than the electron.
 
RADIOMETER - An instrument for detecting and measuring radiant energy.
 
RASTER - A geometric pattern followed by the sending element of a detector system or by the electron beam of a television transmitter or receiver.
 
RATE GYRO - A gyroscope with one free gimbal axis ( precession axis ) . Motion around this axis is constrained by a spring. The second gimbal axis is tied to the spacecraft. An angular motion of the spacecraft around this axis produces an angular excursion of the precession axis against the spring force; the angle of excursion is proportional to the rate of angular rotation in radians per second.
 
REDUCTASE - An enzyme that has a reducing action on chemical compounds.
 
REDUNDANCY - Originally "exceeding what is necessary or normal ;" technically a back - up system which takes over when the prime system fails.
 
RESOLVING POWER (LIGHT) - The ability of an optical system to separate adjacent points and lines in the image and to show fine detail of the target.
 
RNA - Ribonucleic acid, a nucleoprotein found in the cell's cytoplasm. It probably controls protein synthesis under the regulatory influence of DNA. See DNA.
 
S - BAND - A range of frequencies used in radar and communications that extends from 1,550 to 5,200 megahertz (wavelength region from 0.06 m to 0.2 m).
 
SCINTILLATION - A flash of light produced in a phosphor by an ionizing particle or photon.
 
SINGLE CRYSTAL - A crystal having a homogeneous, undisturbed lattice structure throughout.
 
SLEW - To change the direction of an antenna or telescope in order to follow a moving target, or to change from one target to another.
 
SOLAR WIND - Streams of particles (mostly ions of hydrogen and helium, and electrons ) emanating from the Sun and flowing approximately radially outward at velocities from 300 to 800 km per sec.
 
SPECTROSCOPE - An optical instrument which spreads a beam of electromagnetic radiation into a spectrum of different wavelengths for visual inspection.
 
SPECTROGRAPH - Modification of a spectroscope in which the spectrum is photographed or recorded electronically.
 
SPECTROHELIOGRAPH - A modification of the spectrograph which permits taking pictures of the complete solar disk in monochromatic light.
 
SPIROMETER - An instrument to measure the breathing volume.
 
SUNSPOTS - Dark, irregular areas on the solar surface with strong magnetic fields (1000 to 2000 Gauss) surrounded by gray zones (penumbra). Sunspots occur mostly in pairs, with opposite magnetic polarity; they persist for periods of days, weeks, or months. Their temperatures are about 2000 K lower than the temperature of the surrounding photosphere (5780° K). The frequency of sunspots follows an eleven - year cycle.
 
SUPERGRANULATION - A net - like pattern of irregular cells, 15,000 km (800 naut. ml.) to 40,000 km (22,000 naut. ml.) in diameter, superimposed upon the photospheric granulation network, and caused by plasma convection within the chromosphere. Cell lifetime is about 20 hours. Supergranulation is best observed in the monochromatic light of a calcium spectral line.
 
SYNOPTIC - Observing different objects, or different aspects of one object, at the same time.
 
SYRINGE - An instrument for injecting or extracting liquids into or from any vessel or cavity, such as a vein in the human body.
 
TERRESTRIAL - Of or pertaining to the Earth.
 
TOXIN - A soluble poison produced and liberated by certain bacteria, insects, snakes, and plants. Toxins arc usually protein substances which may be destroyed by heat.
 
VECTORCARDIOGRAPH - An instrument for taking a graphic record of the magnitude and direction of the electrical potentials of the heart.
 
VELCRO - A fastener for quick attachment (and subsequent detachment) of an object to another object, or to a surface. It has two parts, a pad consisting of velvety, loopy pile made of Teflon, and a pad consisting of little hooks resembling a cockleburr, made of polyester. Attachment by pressing the two pads together, detachment by pulling them apart.
 
VESTIBULAR - Pertaining to the organs of the inner ear that provide a sense of equilibrium for animals and man.
 
VIDEO - Pertaining to the picture signals in a television system, or to the information-carrying signals which are eventually presented on the cathode ray tubes of a radar system.
 
ZEOLITE - A group of hydrous silicates of aluminum, containing sodium and calcium, and giving off water upon heating; technically, a substance capable of absorbing large quantities of carbon dioxide.
 
ZODIACAL LIGHT - A faint light emanating from a region in the night sky roughly defined by the zodiac. This light results from sunlight scattered by fine dust particles that orbit the Sun at planetary distances; it is enhanced in the vicinity of the Sun.
 
* For comparison, the Earth's magnetic field near the surface is 0.6 Gauss.