Glossary

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16S rRNA

70S Ribosome is composed of 2 subunits: 50S and 30S. 30S subunit is composed of 21 ribosomal proteins and 16S ribosomal RNA. Evolution of 16S rRNA is extremely conserved throughout all life domains due to the crucial function in the production of proteins. 16S is the most used phylogenetic marker.

Accretion

Accumulation of dust and gas into larger bodies such as stars, planets and moons, or as discs around existing body. An accretion disc (or accretion disk) is a structure formed by diffuse material in orbital motion around a central body. Instabilities within the disc redistribute angular momentum, causing material in the disc to spiral inward towards the central body

Acetaldehyde

CH3CHO

Acetamide

CH3CONH2

Acetic Acid

CH3COOH

Acetonitrile

CH3CN, cyanomethane, methyl cyanide

Acetyltransferase

An enzyme that catalyzes the transfer of acetyl (the acetic acid radical CH3CO) groups from one compound to another.

Acidithiobacilus

Acidithiobacillus is a genus of proteobacteria. The members of this genus used to belong to Thiobacillus, before they were reclassified in the year 2000.

Active Seti

Deliberte transmission of messages from Earth, for the purpose of initiating communication with Extra-Terrestrial Intelligence. Also known as METI (Messaging to Extra-Terrestrial Intelligence).

Adenine

One of the four nuclear bases of ADN and ARN, and a component of ATP. This molecule of global formula H5C5N5 is a puric base (derivative of purine) and is made of two heterocycles of 5 and 6-atoms . It plays an important role in the living world as component of nucleotides.

Aeolian

Caused by, or carried by the wind; Also spelled eolian.

Aerogel

Aerogel is a low-density solid-state material derived from silicone gel in which the liquid component of the gel has been replaced with gas. The result is an extremely low density solid with several remarkable properties, most notably its effectiveness as an insulator. It is nicknamed frozen smoke, solid smoke or blue smoke due to its semi-transparent nature and the way light scatters in the material. Aerogel was used as the high speed capture medium for comet dust by the Genesis and Stardust spacecrafts.

Aerosol

Aerosol technically refers to airborne solid particles (also called dust or particulate matter) or liquid droplets.

Afrho

Standard planetary science abbreviation used in cometary studies. The value is a proxy for the dust production of a comet.

Albedo

Albedo (often geometric albedo) is defined in various ways, but is fundamentally the ratio of the intensity of light diffusely reflected from a surface to the intensity of the incident light (usually sunlight). Fresh snow has an albedo of about 0.9, while powdered elemental carbon has albedo less than 0.05.

Aliphatic Hydrocarbons

The simplest organic compounds, containing straight chains of carbon and hydrogen.

Alkaliphilic

Organisms that grow optimally or very well at pH values above 9, often between 10 and 12, but cannot grow or grow only slowly at the near-neutral pH value of 6.5

Amadori Rearrangement

One of the steps in the Maillard reaction (see Maillard reaction).

Amino Acids

A general class of organic molecules with a tetravalent carbon atom bonded to a hydrogen atom, an amino group (NH2), a carboxyl group (COOH), and an organic group (R) giving a general formula CHR(NH2)COOH; slight variations on this general formula are known.

Amorphization

The process of turning into amorphous phase. Amorphous refers to a lack of order in the arrangement of the atoms.

Amorphous Ice

Phase of water ice in which there is no long-range order of the positions of the atoms (as opposed to crystalline ice; see definition of mineral). Amorphous ice forms when water vapor condenses on a surface maintained below around 120K.

Amphibole

An important group of rock-forming, hydrated (containing an OH group) silicate minerals that form prism or needlelike crystals (see definition of silicate). They have the inosilicate (double chains) structure, composed of double chain SiO4 tetrahedra, linked at the vertices. They are generally generally dark-colored, and contain ions of iron, magnesium, calcium and aluminum in varying amounts.

Amphiphile

Amphiphile is a term describing a chemical compound possessing both hydrophilic and hydrophobic properties. Such a compound is called amphiphilic or amphipathic. This forms the basis for a number of areas of research in chemistry and biochemistry, notably that of lipid polymorphism.

Anaerobic Chemoautotroph

An organism that obtains energy from the metabolism of inorganic chemicals from the environment without the use of oxygen. Autotrophs synthesize organic chemicals necessary for growth from CO2.

Anneal

Change occuring in the structure of a material due to the application of heat and/or pressure. In this context, it refers to low temperature amorphous ices when the ice is heated, allowing for an internal re-structuring of the ice matrix. As the ice restructures, pore space can decrease and other trapped molecules can get released in the process, resulting in one possible cause of volatile escape in icy bodies at low temperatures.

Anoxic

Means without oxygen.

Antiamoebin

A type of polypeptide that is capable of forming ion channels in phospholipid membranes. It is produced by fungi of the species Emericellopsis and has antibiotic properties against the organisms responsible for amoebic dysentry.

Aphelion

Term defining a specific point in an orbit. The prefix ap refers to the farthest point from the focus of an elliptical orbit, and helion (from helios) refers to the sun. Aphelion is the farthest point in an orbit about the sun.

Apparent Brightness

The brightness of an astronomical object, such as a star or a comet, as viewed or measured from the Earth.

Arc Second

An angular measure. Each degree of angle contains 3600 arc seconds, or 60 arc minutes. Each arc minute of angle contains 60 arc seconds.

Archean

Used to describe rocks from the Archeozoic time period. This geologic time is the earlier part of the pre-Cambrian time corresponding to 4.6 to 2.5 billion years before the common era; the later being the Proterozoic.

Arecibo Message

A deliberate transmision from Earth on 16 November 1974, beamed toward the M-13 cluster on 2380 MHz during ceremonies to dedicate the refurbished Arecibo Observatory. The Message consisted of 1679 bits, to be arranged in 73 rows by 23 columns (those both being prime numbers). It graphically described a binary number sequence, hydrocarbon chemistry, DNA, the human figure (including a height scale), our solar system, and the Arecibo dish transmitting the signal.

Arkose

A sandstone rich in feldspar, the family of K, Na, Ca aluminosilicate minerals that are abundant in igneous and metamorphic rocks.

Aromatic Hydrocarbon

A planar ring of six carbon atoms (usually described as having alternating single and double bonds) having bound hydrogen atoms. The simplest such molecule is benzene, which has a chemicial formula C6H6. Other atoms and functional groups can replace hydrogens to make more complex molecules. Multiple fused aromatic hydrocarbons are called polycyclic aromatic hydrocarbons, or PAHs.

Asteroid

Small (< 1000 km) rocky body orbiting the Sun. Many of them orbit between Mars and Jupiter (main asteroid belt)

AU

AU = Astronomical Unit, which is the average distance from the Earth to the Sun.

Autotrophy

Synthesizing organic molecules from inorganic ones.

Bacillus Subtilis

A gram-positive soil bacterium that forms hardy dormant spores. Because the spores are highly resistant to a wide variety of physical insults, B. subtilis is widely used as a model organism for astrobiological and space flight studies.

Bacteriophage

A virus that infects bacteria.

Banded Iron Formation

A rock that consists of alternating bands of iron-rich minerals, generally hematite (Fe2O3), and chert or fine-grained quartz (SiO2).

Barycenter

Center of mass

Basal Metazoans

The groups comprising the root of the animal tree of life, namely Poriferans, Cnidarians, Ctenophores, and Placozoans.

Basalt

A dark, fine-grained, extrusive (volcanic) igneous rock with a low silica content (45% to 52% SiO2), but rich in iron, magnesium and calcium. It is composed largely of plagioclase feldspar and pyroxene, but may also be rich in olivine. Generally occurs in lava flows, but also as dikes. Basalt makes up most of the ocean floor and is the most abundant volcanic rock in the Earth''s crust.

Baseline

The vector between any two telescopes of an interferometer. It has both an azimuthal direction relative to the compass, and a length.

Basement

Basement rocks refer to the oldest geologic layers in the stratigraphic collumn. These are usually metamorphic and can be also referred to as crystalline basement rocks.

Bathymetry

Refers to the measurement of the depth of a body of water.

Bioma

Life zone with similar characteristics.

Biomonomers

Molecules that are the buiding blocks of biopolymers : proteic amino acids for proteins ; nucleotides for RNA or DNA.

Biopolymers

Biopolymers are a class of polymers produced by living organisms, also known as biological polymers. DNA, RNA, and proteins are all examples of bipolymers.

Biosensor

A biosensor is a device for the detection of an analyte that combines a biological component with a physicochemical detector component.

Biosilicification

The process in which biosignatures are created by the interaction of organic materials (especially saccharides) with silicates.

Black Holes

When the density of matter becomes great enough the gravitational field becomes so strong that not even light can escape. The event horizon is the boundary between where light can and cannot escape.

Black Smoker

Also called hydrothermal vent. Structure observed on the oceans floor generally associated with mid ocean ridges. There, hot hydrothermal fluid, rich in base metal sulphides, enters in contact with cold oceanic water. Polymetallic sulphides and calcium sulphate precipitate progressively building a columnar chimney around the vent.

Bolide

A bright meteor that explodes or strikes the earth -- a fireball and/or meteorite.

Brown Dwarf

A substellar (i.e. not a true star) object that lacks sufficient mass to ignite hydrogen fusion.

Carbonaceous Chondrite

A class of meteorites that have elemental abundance ratios of certain rock-forming elements that are nearly identical to the ratios observed in the sun. Carbonaceous chondrites include the carbon-rich meteorite classes CI, CM, and CR, and the chondrule-rich classes CV, CO, and CK, and the minor groups CB and CH.

Carbonate

A group of minerals composed primarily of a divalent cation (e.g., Ca, Na, Mg, Fe., etc.) and CO3. Carbonates can be formed through chemical precipitation (supersaturation due to temperature decrease), biochemical processes (e.g., shells, coral), by metamorphic processes, igneous crystallization and by the evaporation of water. The two most abundant carbonate minerals in today''s oceans are calcite and aragonite, two different arrangements of CaCO3. Dolomite (Ca,Mg)CO3 is another common carbonate mineral in ancient sediments.

Carcinogenesis

Carcinogenesis is the molecular process by which normal cells are transformed into cancer cells.

Cellular Automaton

A cellular automaton (CA) is a computational model that is discrete in both space and time. Essentially we divide space into boxes called cells, and only calculate their values at discrete time instants (you could consider this as dividing space-time into boxes if you like). CA use a set of fixed rules to transition from one state (value of the cell) to another.

Centaur

An object whose orbit around the Sun crosses the orbit(s) of one or more major planets. These objects are thought to have been ejected from the Kuiper Belt and their planet-crossing orbits are temporary (~10,000 years or less) because of dynamical interactions with the planets. Some Centaurs exhibit cometary activity.

Chemotrophy

Metabolic system using a chemical energy source, rather than e.g. light-energy

Chert

Chemical sedimentary rock, most commonly deposited on the seafloor by chemical precipitation from the ocean water, composed of very fine crystals of quartz or silica (SiO2)

Chiral

Used to describe an object that is non-superimposable on its mirror image, such as the human hand. In terms of chemistry, these objects are usually molecules. The two mirror images of a chiral molecule are referred to as enantiomers, the left and right hands. For organic molecules such as amino acids, chirality is a powerful tool that can be used to discriminate between abiotic (non-biological) and biotic (biological) origins.

Chon Particle

Cometary dust particle rich in Carbon, Oxygen, Nitrogen, Hydrogen. CHON particles were identified in comet Halley from in situ mass spectrometry

Chromatic Complementary Adaptation

Adaptation of the living organisms to the properties of light through the biosynthesis of pigments (optically active biomolecules) and development of coloration. CCA is essential for energy harvesting from the parent star in accordance with it''s spectral characteristics.

Chromospheric

Pertaining to the chromosphere, a complex warm gaseous layer that lies above the visible surface of the Sun.

Circularly Polarized Light

Light with the electric field component (vector) tracing out a circle as the light propagates from the source to the observer. One proposal for the origin of chirality (handedness) of biomolecules, such as amino acids, is the influence of circularly-polarized light on pre-biotic material.

Clathrate

A clathrate or clathrate compound or cage compound is a chemical substance consisting of a lattice of one type of molecule trapping and containing a second type of molecule. (The word comes from the Latin clathratus meaning furnished with a lattice). For example, a clathrate hydrate involves a special type of gas hydrate that consists of water molecules enclosing a trapped gas. Scientists believe that compounds on the sea bed have trapped large amounts of methane in similar configurations. Researchers have begun to investigate silicon and germanium clathrates for possible semiconducting and superconducting properties. A clathrate therefore is a material which is a weak composite, with molecules of suitable size captured in spaces which are left by the other compounds. They are also called host-guest complexes, inclusion compounds, and adducts (chiefly in the case of urea and thiourea). They used to be called molecular compounds.

Clay Mineral

Clay minerals are hydrous phyllosilicates, sometimes with variable amounts of iron, magnesium, aluminium, alkali metals (e.g. Na, K, etc.), alkaline earths (e.g. Mg, Ca, etc.) and other cations. Clays have structures similar to the micas and therefore form flat hexagonal sheets. Clay minerals are common weathering products (including weathering of feldspar, pyroxene and olivine) and low temperature hydrothermal alteration products. Clay minerals are very common in fine grained sedimentary rocks such as shale, mudstone and siltstone, in fine grained metamorphic slate and phyllite, and in meteorites which have experienced hydrothermal alteration or aqueous alteration.

Clonal

Population generated upon replication of a single molecule or a single individual. A clonal population in virology designates an ensemble of progeny viruses that arise from replication of a single virus during a limited number of replication rounds. The standard method to isolate clonal populations of viruses is the development of lytic plaques.

Clone

1. Clone: a cell, group of cells, or organism that is produced asexually from and is genetically identical to a single ancestor. The cells of an individual plant or animal, except for gametes and some cells of the immune system, are clones because they all descend from a single fertilized cell and are genetically identical. A clone may be produced by fission, in the case of single-celled organisms, by budding, as in the hydra, or in the laboratory by putting the nucleus of a diploid cell into an egg that has had its nucleus removed. Clones of other cells and some plants and animals can also be produced in a laboratory. 2. Clone: A copy of a sequence of DNA, as from a gene, that is produced by genetic engineering. The clone is then transplanted into the nucleus of a cell from which genetic material has been removed. (Source: American Heritage Science Dictionary)

Cm Meteorites

The most abundant type of carbonaceous chrondrite meteorite; possesses essentially a solar composition, aside from the more-volatle elements (e.g. H, He, O, etc.); contains organic and hydrated compounds and is thought to represent relatively primitive solar-system material.

Codon

The genetic code is the set of rules by which information encoded in genetic material (DNA or RNA sequences) is translated into proteins (amino acid sequences) by living cells. Specifically, the code defines a mapping between tri-nucleotide sequences called codons and amino acids; every triplet of nucleotides in a nucleic acid sequence specifies a single amino acid.

Collective Intelligence

Evolved stage of advanced civilizations where the dominant paradigm to resolve conflicts is through collaboration and non-violence. Our planet might start to witness an Earth Community, where all earthlings have covered their basic needs.

Color

A measure of the relative fluxes or reflectivities at 2 wavelengths or wavelength intervals. In a magnitude system it is the difference between two magnitudes.

Column Density

The number of atoms of a certain element as seen along a line-of-sight projected to a unit area at the observer (often in units of atoms/cm^2).

Coma

The nebulous luminescent cloud of volatile elements and molecules, containing the nucleus and constituting the major portion of the head of a comet.

Comet

Small icy solar system body thought to be a remnant of the formation of the solar system, likely formed in the vicinity of the giant planets.

Cometary Tails

Most visible part of an active comet. There are two main tails : the blueish, straight ion tail, and the white-yellow , curved, dust tail. These tails may reach up to a fraction of an astronomical unit in some cases. A neutral sodium tail has also been observed.

Commensal

Literally means eating from the same plate. In biology this refers to a symbiotic relationship between two organisms in which benefit to one organism does not affect the other. In astronomy it is used to mean multiple-concurrent observations that can be conducted without detriment to one another.

Confusion Limit

Spectral line data at radio wavelengths where the data in no longer noise limited. Spectral lines cover the the full spectral range, such that no baseline noise is present. Can occur in dense molecule clouds.

Continuously Habitable Zones (Chzs)

A region of space around a star where a planet can sustain liquid water at its surface, for at least part of its local year, considered over a long enough period for sophistocated life to emerge.

Cosmochemistry

Crism

Compact Reconnaissance Imaging Spectrometer for Mars (CRISM) launched on the Mars Reconnaissance Orbiter in August 2005 and is currently mapping Mars. It is a visible-infrared hyperspectral mapper in the wavelength range from 0.36-3.92 micrometers

Cryogenic Volcanism

The eruption of volatiles (usually water) on the surface of a planet or moon which then cools and freezes into a new layer of crust, similar to the eruption of silicate magma.

Cryostat

A cryostat is, in the general sense, a device used for maintaining the low temperature of an object.

Crystalline Ice

The phase of water ice exhibiting a structure with the long-range order of a mineral. Crystalline ice is typically found in its hexagonal form, but sometimes exists in the metastable cubic form. Upon warming, cubic ice will transform irreversibly to hexagonal ice.

Cyanhydric Acid

HCN, hydrogen cyanide. In prebiotic chemistry, may have been the starting material for purine synthesis.

Cyanoacetylene

HC3N, cyanoethyne

Cyanobacteria

From the Greek word kyan, meaing blue. Also known as Cyanophyta is a phylum (or division) of Bacteria that obtain their energy through photosynthesis.

Cyanogen

C2N2

Damped Lyman-Alpha Systems (Dlas)

Intervening absorbing gas between us and a background source of light such as a QSO (galaxies with bright nuclei due to powerful central black holes). DLAs are defined as those intervening sources with the greatest neutral hydrogen content, often presumed to be due to a galaxy.

Darwin

Project of space infrared interferometer devoted to the search of extrasolar planets and the study of their atmosphere composition. CO2, O3 and H2O have IR bands in the 6-20 microns range ; their simultaneous detection is under study as signature of (biological) photosynthetic processes. The TPF-C and TPF-I projects (Terrestrial planet finder - coronograph and -interferometer) have similar goals.

Daughter Species

Produced by photodissociation (or other type of chemical splitting) of parent molecule. For example, in the coma of a comet (e.g., OH from H2O); note that the parent(s) of some commonly observed radicals (C2, C3, CN) are uncertain.

Debris Disk

A disk of dust particles around a star that is formed through collision of planetesimals (see planetesimal for its definition).

Derivatization

A technique used in chemistry which transforms a chemical compound into a product that is more easily detected or analyzed. OPA/NAC derivatization is often used to label amino acids with a chiral fluorescent tag, increasing the detection sensitivity for the compound and enabling the separation of amino acid enantiomers using standard liquid chromatography techniques.

Devolatilized

Used to describe materials that have lost their volatile components (e.g., CO2, H2O, etc.)

Diagenesis

The process by which sediment undergoes chemical and physical changes during its lithification (conversion to rock). Compaction, leaching, cementation, and recrystallization are all forms of diagenesis. Erosion and metamorphism are not. Oil, gas, and coal form through the diagenesis of organic sedimentary matter.

Diffuse Interstellar Bands

Absorption profiles commonly observed towards reddened stars in the Milky Way. Current work points to organic molecules such as carbon chains and polycyclic aromatic hydrocarbons as the likely sources of the diffuse interstellar bands (DIBs). The hundreds of observed DIBs to date fall within the visible part of the electromagnetic spectrum.

Dihydroxyacetone

HOCH2COCH2OH

Diurnal

Relating to or occurring in a 24-hour period; daily.

Dosimeter

A dosimeter is a device that is used to measure an individual''s exposure to a hazardous environment. A radiation dosimeter, for example, is a device that measures the cumulative dose of radiation.

Drake Equation

The Drake equation (rarely also called the Green Bank equation or the Sagan equation) is a famous result in the speculative fields of exobiology, astrosociobiology and the search for extraterrestrial intelligence and identifies specific factors thought to play a role in the development of such civilizations. This equation was devised by Dr Frank Drake (now Emeritus Professor of Astronomy and Astrophysics at the University of California, Santa Cruz) in the 1960s (first proposed in 1961) in an attempt to estimate the number of extraterrestrial civilizations in our galaxy with which we might come in contact. The main purpose of the equation is to allow scientists to quantify the uncertainty of the factors which determine the number of extraterrestrial civilizations. Although there is no unique solution to this equation, it is a generally accepted tool used by the scientific community to examine these factors.

Dust

(Interstellar, interplanetary, cometary dust) : Small solid particles (0.1 microns to 1 mm), generally made of silicates, metal ions and/or carbonaceous matter.

EA

Ethylamine (EA) is a chemical compound with the formula CH3CH2NH2. It has a strong ammonia-like odor. It is miscible with virtually all solvents and is considered to be a weak base, as is typical for amines. Ethylamine is widely used in chemical industry and organic synthesis. It is also used in cigarettes.

Eaca

Epsilon amino-n-caproic acid or 6-aminohexanoic acid. Found in Nylon-6.

Earthshine

Light and energy radiated from Earth into space, usually used to refer to the illumination of the dark side (opposide the Sun) of the Moon.

Ecologite

A metamorphic rock formed under high pressure, dominated by garnets and olivine, with a composition similar to basalt.

EE

Enantiomeric excess

Enantiomeric Excess

In the case of a mixture of two enantiomers whose respective concentrations are D and L with D greater than L, i.e. the enantiomeric excess in percent is 100x(D - L)/(D + L)

Enantiomers

Two isomeric molecules that are non-superimposable mirror-images of each other. A typical usage is enantiomeric excess (abbreviated ee) and often defined as the absolute value of the differences in fractional abundances of enantiomers in a mixture.

Endergonic

Absorbing energy, in the form of work

Energy Transduction

Energy transduction refers to any cellular mechanism used to transform a source of external energy (radiation, chemical) in energy usefful for the cell (respiration, photosynthesis, fermentation).

Entropy

Denoted by S, is a measure of the extent of disorder. It can also be described as a quantitative measure of the amount of thermal energy not available to do work.

Enzyme

Any of numerous proteins produced in living cells that accelerate or catalyze the metabolic processes of an organism.

EPO

Education/Public Outreach

Equivalent Width

The width of a box reaching up to the continuum that has the same area as the observed spectral line.

Ethylene Glycol

CH2OHCH2OH. The simplest dialcohol

Evaporite

A mineral that precipitates during the evaporation of salty water. Sulfates and carbonates are examples of evaporite minerals.

Evpatoria Messages

An ongoing series of powerful microwave transmissions from Earth, starting in 1999, directed toward specific sun-like stars, beamed from the Evpatoria radar telescope in the Ukraine.

Excentricity

Parameter (e) characterizing the shape of an orbit. e is equal to 0 for a circle, equal to 1 for a parabola, higher than 1 for a hyperbola and between 0 and 1 for an ellipse.

Exergonic

Releasing of energy, in the form of work

Exoplanet

Synonym of extra-solar planet

Extrasolar Planet

A planet that orbits a distant star - a star located far away from our Sun, outside the reaches of our solar system. In the past decade or so, more than 200 extrasolar planets have been detected in orbit around distant stars in our galaxy. Also extra-solar planet.

Extremophiles

An extremophile is an organism, usually unicelular, that requieres extrem conditions for growth and reproduction. Those conditions exceeds optimal conditions for mesophiles organisms.

Feldspar

A group of abundant rock-forming minerals of the general formula XAl(Al,Si)3O8 where X can be K, Na, Ca, Ba, Rb, Sr or Fe. Feldspars constitute 60% of the Earth's crust and occur in all types of rocks (igneous, sedimentary, metamorphic). Two common types of felspars are plagioclase feldspar (X=Na or Ca) and orthoclase (X=K).

Ferric Iron

Iron with an oxidation number of +3 (i.e. Fe3+)

Ferrous Iron

Commonly known as Iron(II) oxide. It consists of the chemical element iron in the oxidation state of 2 bonded to oxygen (i.e. Fe2+O)

FFT

Fast Fourier Transformation

Field Of View

The instantaneous region of the sky that is accessible to an observing instrument is its field of view.

Fluorescence

Atoms, molecules and solids that are excited to higher energy levels, can decay to lower energy levels by emitting electromagnetic radiation at specific wavelengths.

Flux

The net energy flow across an element of area per second per wavelength interval.

Formaldehyde

H2CO, methanal. The simplest aldehyde. Polymerizes easily (e.g. POM). In prebiotic chemistry, may have been the starting point of ose formation (formose reaction).

Formamide

NH2CHO

Formic Acid

HCOOH

FTIR

Fourier transform infrared spectroscopy

Full Width Half Maximum

Abbreviated FWHM. A measure, in either frequency or anglular size, of the location where the measured intensity has been reduced to half its peak value.

Genome

Hereditary information of an organism. It is constituted by a nucleotide sequence that can be DNA (in cellular genomes and in DNA viruses) or RNA (in RNA viruses)

Geophysiology

The dynamic processes and feedbacks of the biosphere, life and its interacting environment. Geophysiology is analogous to the physiology of living organisms, but it need not imply that the biosphere is a superorganism as in some versions of Gaia theory.

Geothermal

Thermal energy that comes from within the Earth

Giant Planet

A general term indicating a planet similar to Jupiter in mass and size.

Gibb's Energy

Amount of energy available from chemical reactions; dG = dG0 + RT ln Q dG = Gibbs energy of rxn, dG0 = standard state Gibbs energy of rxn, R = universal gas constant, T = absolute temperature, Q = activity quotient of reaction.

Gigahertz

Abbreviated GHz. A frequency of 1 billion hertz or 1 billion cycles per second. A radio signal with a frequency of 1 GHz has a wavelength of 30 cm.

Glucose

A sugar (C6H12O6) occurring widely in most plant and animal tissue. It is the principal circulating sugar in the blood and the major energy source of the body.

Glutamic Acid

A nonessential amino acid, C5H9NO4, occurring widely in plant and animal tissue and proteins, and having monosodium glutamate as a salt. Plays a central role in amino acid metabolism, acting as precursor and also acts as amino group donor for other amino acids. It is also a neurotransmitter, important in the nitrogen metabolism of plants; used in monosodium glutamate to enhance the flavor of meats.

Glycine (Gly)

NH2CH2COOH. The simplest amino acid and the only one which is not chiral. One of the 20 proteic amino acids.

Glycolaldehyde

CH2OHCHO

Greenstone

Metamorphosed basalts. Greenstone belts are common in the Archean.

H-Alpha

An emission line of Hydrogen (n=3 to 2) at 653nm (red). This emission line is thought to trace accretion and circumstellar-material in young stars.

Hadean

Geological time period from the formation of the Earth at 4.5 billion years ago to the beginning of the Archean at 3.8 billion years ago

Hapke Theory

Sattering model devised by Bruce Hapke, incorporating the optical properties of the particles making up a diffusely reflecting particular surface. The Hapke theory has been widely tested and is used by many investigators for the calculation of synthetic spectra of Solar System bodies by the incorporation of the complex optical refractive indices of the component(s) of the scattering surface.

Heliosphere

The immense magnetic bubble carved out in space by the solar wind that defines the extent of the Sun''s influence (helios.gsfc.nasa.gov/heliosph.html).

Hematite

Hematite, also spelled haematite, is the mineral form of Iron(III) oxide, (Fe2O3), one of several iron oxides.

Hertz

Abbreviated as Hz. A unit of frequency equal to 1 cycle per second. The alternating current delivered by wall sockets in the US (Europe) oscillates with a frequency of 60 Hz (50 Hz).

Heterocycles

Cyclic compounds in which carbon is substituted by other elements, typically oxygen, nitrogen, or sulfur.

Heterogeneous Reaction

The reaction between reactants that exist in different phases. For example, a common type of reaction studied in atmospheric science is that between a gas species and a solid substrate (ice crystal or aerosol particle).

Homochirality

Term used to refer to a group of molecules that possess the same sense of chirality or handedness. Life on Earth is based on homochirality. For example, active amino acids that are incorporated into proteins and enzymes are in the L-form, while most biologically relevant sugars are in the D-form.

Hot-Jupiter

A Jupiter-like planet in a very close orbit to its host star. The distances of hot-Jupiters to their parent stars are about 100 times smaller than the distance of Earth to the Sun.

Huronian

Glaciation(s) occurring at about 2.4-2.2 billion years ago

Hydrogen Bonding

A weak bond in which the electron is shared with the hydrogen atom.

Hydrogeological

Refering to the study of the water in the subsurface

Hydrolysis

A chemical reaction in which a chemical compound reacts with water, usually resulting in the formation of aqueous ionic compounds and/or hydrated molecules.

Hydrothermal Vent

See Black smoker

IETI

Invitation to ETI: a web-based SETI project for initiating dialog with possible extraterrestrial intelligent autonomous probes surveying our civilization. http://ieti.org.

Igneous

Igneous rocks are formed by the crystallization (freezing) of magma (molten rock).

Imidazole

An organic crystalline base, C3H4N2, that is an inhibitor of histamine.

Interferometer

A larger telescope that is created by combining the signals from a number of smaller telescopes. The sensitivity of an interferometer is determined by the total collecting area of all the individual telescopes. The spatial resolution of an interferometer is determined by the longest baseline between any two telescopes.

Ion Channels

Ion channels are pore-forming proteins that help to establish and control the small voltage gradient across the plasma membrane of all living cells by allowing the flow of ions down their electrochemical gradient. They are present in the membranes that surround all biological cells.

Ir Spectroscopy

Abreviation of Infra-red spectroscopy. It is very powerful in determining the presence of various minerals and compounds, including functional groups in organic compounds.

IRAF

Standard software for the analysis of astronomical data, primarily images and spectra. Acryonym stands for Image Analysis and Reduction Facility. Developed at the National Optical Astronomy Observatories in Tucson starting in the 1980s.

ISM

Interstellar medium

ISO

Infrared Space Observatory. Space telescope for infrared light designed and operated by the European Space Agency (ESA), in cooperation with ISAS/JAXA and NASA. Observed in the 2.5 to 240 microns wavelength range from 1995 to 1997.

Isochronal Ages

An isochron is a line on a plot that shows the relation between the a nonradiogenic isotope divided by the daughter isotope versus the parent isotope divided by the daughter isotope. For example, a line on a 232Th/204Pb vs/ 208Pb/204Pb plot or on a 40K/36Ar vs. 40Ar/36Ar plot. A straight line on a plot of this kind is called an isochron and shows that the data points came from minerals which formed at the same time.

Isocyanhydric Acid

HNC. Isomer of cyanhydric acid HCN

Isomer

One of two or more forms a chemical compound which have the same number and type of each atom but a different arrangement of atoms, but possessing different properties. There are structural isomers, geometric isomers, optical isomers, and stereoisomers.

Isovaline

A non-biological amino acid with the structural formula C(CH3)(CH2CH3)(NH2)COOH; has the highest abundance of any amino acid yet identified in CM meteorites Murchison and Murray.

JFC

Jupiter family comet

K/T (Strata)

Few centimetre-thick sedimentary layer located at the Cretaceous(K)- Cenozoic(Tertiary,T) boundary. Its Iridium- enrichment is interpreted as due to a giant meteoritic impact (K/T event).

Keplerian Speed

The orbital speed of a body under the influence of gravity, usually of a substantially more massive body. For keplerian motion replace motion for speed in the above definition.

Kerogen

Terrestrial kerogen is a dark, complex, macromolecular organic substance produced by geologic processing of biologic materials. Insoluble organic material in some classes of meteorites has a structural similarity to kerogen, but with no biological connotation.

Kuiper Belt

The Kuiper belt, sometimes called the Edgeworth-Kuiper belt, is a region of the Solar System beyond the planets extending from the orbit of Neptune (at 30 AU) to approximately 55 AU from the Sun. It is similar to the asteroid belt, although it is far larger; 20 times as wide and 20-200 times as massive. Like the asteroid belt, it consists mainly of small bodies (remnants from the Solar System''s formation) and at least one dwarf planet Pluto. But while the asteroid belt is composed primarily of rock and metal, the Kuiper belt is composed largely of ices, such as methane, ammonia, and water.

Kuiper Belt Object

An object orbiting the Sun in a region of the Solar System beyond Neptune, and with an orbital extent of about 55 Astronomical Units. KBO orbits are of low inclination to the plane of the planets orbits, and the Kuiper Belt where they occur is regarded as the source region of the short-period (P less than about 200 years) comets.

Langmuir

Three-dimensional macroscopic (by amplitude about some microns) oscillations of dissociated H+ proton on the net of hydrogen bonds

Lc/Fd-Tof-Ms

Liquid chromatography with UV fluorescence detection and time of flight mass spectrometry. This is a powerful analytical technique that can be used to separate a complex mixture of organic compounds (for example in carbonaceous meteorites)and identify each compound uniquely by the time it takes for the molecule to elute from the column, the exact mass of the compound, and UV fluorescence.

Limb

Appendage of an animal such as an arm or a leg

Limb

Large branch of a plant

Limb

The visible edge of a disk, such as the limb of the Sun or a planet, sometimes used as an adjective (e.g., limb darkening)

Lithopanspermia

(Litho, rock; panspermia, literally = seeds everywhere). Originally proposed in the 19th century by Richter, Lord Kelvin, and von Helmholtz. In its current form, the theory that endolithic organisms can be transferred between planets as passengers inside impact ejecta. A theory of Hoyle & Wickramasinghe that suggests that seeds, spores and microbes exist in space and that life on Earth may have originated through panspermia. Lithopanspermia hypothesizes that microbes are incoporated into meteorites which then impact on planets

Lithotrophy

Metabolic system that requires inorganic compounds as sources of energy

Luminosities

An intrinsic measurement of the amount of energy a stellar body radiates per unit time.

Lyman-Alpha

The n=2 to n=1 Hydrogen transmission at 97.2 nm (972 Angstroms). Lyman-alpha is measured in absorption in damped Lyman-alpha (DLA) galaxies to measure the total neutral hydrogen content (see Damped Lyman-Alpha Systems).

Lyman-Alpha

The n=2 to n=1 Hydrogen transmission at 121.6nm (or 1216 Angstroms). Lyman-alpha is measured in absorption in damped Lyman-alpha (DLA) galaxies to measure the total neutral hydrogen content (see Damped Lyman-Alpha Systems).

MA

Methylamine (MA) is the chemical compound with a formula of CH3NH2. It is a derivative of ammonia, wherein one H atom is replaced by a methyl group. MA is used both as a solvent and as a building block for the synthesis of other organic compounds.

Magnetite

A black, strongly magnetic opaque mineral of the spinel group and having the chemical formula Fe3O4 (containing both Fe2+ and Fe3+). Magnetite is very common and widely distributed accessory mineral in rocks of all kinds, especially volcanic and metamorphic rocks.

Magnetospheric Emission

Relating to emissions from an astronomical object, usually a planet, that are powered by its magnetic field. Typically these emissions are generated in the radio part of the electromagnetic spectrum. In the solar system, Jupiter, Saturn, Uranus, Neptune, and Earth all have strong magnetic fields. Interactions between their magnetic fields and particles streaming outward from the Sun generate these magnetospheric emissions. By analogy, extrasolar planets have been hypothesized to be detectable from their magnetospheric emissions.

Magnitude

A measure of the brightness of a star on a logarithmic scale. Original scheme, devised a couple thousand years ago, gave the brightest stars in the sky the lable of first magnitude or first importance, the next brightnest second magnitude. This was quantized later, as the eye is a logarithmic detector, to a system where magnitude = 2.5 log (flux).

Maillard Reaction

The Maillard reaction is the reaction between the amino acids and sugars. It yields a complex mixture of materials, including heterocyclic compounds and the insoluble organic materials, similar to those that are found on the meteorites.

Maser

A maser is a device that produces coherent electromagnetic waves through amplification due to stimulated emission. Historically the term came from the acronym "microwave amplification by stimulated emission of radiation" although modern masers emit over a broad portion of the electromagnetic spectrum.

Mass-Independently-Fractionated

A process in a three isotope system (e.g. O16, O17, O18) by which the isotopes are fractionated differently than what is expected from mass differences. For example, in the oxygen system there are three isotopes with masses 16, 17 and 18. Normal mass-dependent fractionation results in the reaction rate of 17 half-way between that of 16 and 18. This results in a slope one-half line on a three isotope plot (e.g. terrestrial fraction line). However, mass-independent fractionation results in a trend different from the one-half slope. A common example of mass-independent fractionation is the production of ozone (O3) from oxygen gas (O2). It is unknown why this should be the case.

Megahertz

Abbreviated MHz. A unit of frequency of 1 million hertz, or 1 million cycles per second. A radio signal with a frequency of 1 MHz has a wavelength of 30,000 cm = 3 km.

Meridian

A longitudinal reference line that traverses the earth in a north-south direction.

Meridiani Planum

A plain located 2 degrees south of Mars'' equator, the landing site for the second of NASA''s two Mars Exploration Rovers, named Opportunity.

Metagenome

Metagenomics, also called environmental genomics or community genomics, involves the use of molecular biology and bioinformatics to examine DNA extracted from an environmental sample, bypassing the need to cultivate (or even know) the organisms from which the DNA originates. The metagenome is hence the total genomic content of all organisms in a given sample e.g. the global metagenome is the combined DNA content of all types of life on earth, the Bioastronomy2007 metagenome the combined DNA content of all meeting attendees etc

Metallicities

The fractional abundance of heavy elements (all elements in the periodic table except H and He) relative to H.

Metamorphic

Metamorphic rocks are sedimentary or igenous rocks that have undergone mineralogical changes as a result of being subjected to high temperatures, high pressures, or both.

Metazoa

The multicellular animals that make up the major portion of the animal kingdom; cells are organized in layers or groups as specialized tissues or organ systems.

Metazoan Phylogeny

Evolutionary history of the metazoa; branching patterns describing evolutionary relationships between the metazoa originating at the last common metazoan ancestor

Meteoric

Groundwater which originates in the atmosphere and reaches the zone of saturation by infiltration and percolation.

Meteorite

Extraterrestrial object, fragment of an asteroid, of a planet (like Mars) or of the Moon that falls on the Earth surface.

Methyl Formate

HCOOCH3

Methyl Hydantoines

Hydantoin is a heterocyclic (i.e. ringed) organic compound, also known as glycolylurea.

Meti

Messaging to Extra-Terrestrial Intelligence. Also known as Active SETI.

Mid-Ocean (Mor) Flanks

Oceanic crust is formed at mid-ocean ridges which are places where magma upwells from the mantle to cool and create new crust. The flanks are the parts of the mid-ocean ridge where the elevation decreases to the ocean plateau, much like the flanks of a volcano which decrease down to meet the surrounding land.

Mineral

A naturally-occurring, inorganic substance having a definite chemistry and definite structure.

Mojave Desert

An arid region of southeastern California and portions of Nevada, Arizona and Utah, that occupies more than 25,000 square miles. Situated between the Great Basin Desert to the north and the Sonoran desert to the south (mainly between 34 and 38 degrees N latitudes), the Mojave desert is a rainshadow desert and is defined by a combination of latitude, elevation, geology, and indicator plants.

Molecular Clouds

Collections of gas and dust found in interstellar space. Masses can range from one to a million solar masses. Densities can range from 1000 to a ten million particles per cc. Chemical composition is mostly molecular hydrogen and small amounts of simple inorganic and organic molecules.

Molecular Flexibility

The capacity to adopt different structural configurations as a function of interactions with the environment.

Monophyletic Clade

In cladistics, a clade is a group of organisms consisting of a single common ancestor and all the descendants of that ancestor. Any such group is also considered a monophyletic group of organisms, and can be modelled by a cladogram, a diagram of the organisms in the form of a tree.

Montane

Biogeographic term refering to the highland area located below the tree-line.

MS

Mass spectrometer

Murchison

A CM carbonaceous chondrite which fell in 1969 and was collected soon thereafter. Murchison has abundant organic compounds, including carboxylic acids, amino acids, and sugars.

Mutagens

Physical or chemical agents that increase the mutation frequency above the natural level of an organism.

Neoproterozoic

Geologic time period between 1 billion and 0.54 billion years ago, the last phase of the Proterozoic

Nitrogen Fixation

1. The conversion of atmospheric nitrogen into compounds, such as ammonia, by natural agencies or various industrial processes. 2. The conversion by certain soil microorganisms, such as rhizobia, of atmospheric nitrogen into compounds that plants and other organisms can assimilate. (American Heritage Dictionaries)

NMR

Nuclear Magnetic Resonance spectroscopy is an analytical technique that determines the chemical environment of specific elemental nuclei. It is most powerful in identifying H-, C-, P-, and F-bearing molecules.

Noachian

An epoch (named after Noachis Terra) related to the formation of Mars, between 3800 and 3500 million years ago.

Non-Resonant (Hot-Band) Fluorescence (Infrared)

Radiation process in which (1) a molecule in its ground vibrational state (E0) is excited by solar infrared radiation into a higher vibrational state (E1), and (2) transits to an intermediate state (E2, E0 < E2 < E1) via emission of an infrared photon. H2O hot-band fluorescence provides a means to study the water molecules in the comae of comets from ground-based observatories.

Non-Rhizospheric

Soil without presence of roots.

Nuclear Spin

A quantum-mechanical characteristic, representing the total angular momentum of atomic nucleus. Molecules containing two or more identical nuclei (e.g. H2O, NH3, CH4) display nuclear spin modifications (also referred as isomers) grouped according to their total nuclear spin (I). The H2O molecule is organized into two isomers depending on whether the nuclear spins of its H atoms are parallel (ortho-H2O, I = 1) or antiparallel (para-H2O, I = 0) (see also ortho-para ratio; nuclear spin temperature).

Nuclear Spin Temperature

the temperature that would correspond to a given ortho-para ratio if in local thermodynamic equilibrium; ortho-states are increasingly favored at higher spin temperatures and a statistical equilibrium ratio of 3/1 is reached at ~50 K (see also nuclear spin; ortho-para ratio).

Nucleotide

Molecule made by condensation of a base (purine or pyrimidine), an ose and a phosphate group linked to the ose. Nucleotides are ribonucleotides when the ose is ribose ; they are deoxyribonucleotides when the ose is deoxyribose. DNA is a polydeoxyribonucleotide while RNAs are polyribonucleotides. The symbol of a nucleotide is determined by the base (A for adenine, C for cytosine, G for guanine, T for thymine, U for uracil).

Nucleus (Of A Comet)

Solid part of a comet, of typical diameter 1-100 km. Made of ices (H2O, CO, CO2, CH3OH...) and dust particles (silicates and organics). Also called a dirty snowball, according to F.Whipple.

Oligomerization

Oligomerization is a chemical process that converts monomers (small molecules) to a finite degree of polymerization (i.e. imcomplete polymerization).

Olivine

A green to brown mineral, which consists of a solid-solution series from forsterite (Mg2SiO4) to fayalite (Fe2SiO4). Olivine is a common rock-forming mineral of low-silica igneous rocks, including basalt. It crystallizes early from a magma and weathers relatively easily at the surface of the Earth.

Omega

Observatoire pour la Mine''ralogie, l''Eau, les Glaces, et l''Activite'' (OMEGA) provides compositional information regarding the surface of Mars in 0.5 to 5.2 micron region of the spectrum at 100 meters per pixel.

Oort Cloud

Spherical halo of km-sized icy bodies surrounding the Sun. This extends out to approximately 200,000 times the distance from the Earth to the Sun and contains as much as a trillion bodies.

Ophiolite

Sections of the oceanic crust and the subjacent upper mantle that have been emplaced within continental crustal rocks.

Orbital Eccentricity

A measure of how round or elliptical an orbit is. A perfect circle has an eccentricity of 0 percent, and an extremely elliptical orbit has an eccentricity of just under 100 percent.

Ortho-Para Ratio

The abundance ratio between ortho- and para- nuclear spin modifications (see also nuclear spin, nuclear spin temperature).

Outgassing

Ejection of gasses that were frozen, absorbed or trapped in materials, such as comets.

Oxidative

A process involving a reaction with oxygen. Any process by which the proportion of the electronegative constituent in a compound increase.

Oxide

Oxides are minerals that are composed primarily of oxygen and one or more metals (e.g., Ca, Na, Mg, Fe, Ti, etc.). Magnetite, hematite (iron oxide/rust), and ilmenite are oxide minerals.

P-Cygni Profile

A specific shape of a stellar emission line, like the bright star P-Cygni. The blue side of the line shows strong absorption but the red side of the line is in strong emission. This comes from stellar winds or outflowing circumstellar material.

PAH

Abbreviation for Polycyclic Aromatic Hydrocarbon

Paleoclimate

A climate or condition (pressure, temperature) that existed in geologic past; paleo meaning old or ancient.

Panspermia

Literally, seeds everywhere. The theory that life can originate anywhere in the universe given the proper conditions, and can be propagated through space from one location to another.

Parent (Native) Molecule

Present as ice in the comet nucleus, released directly from the comet nucleus (e.g., H2O, CO, H2CO, HCN, NH3, CH4, C2H2, C2H6).

PC

Abreviation of parsec, which is itself an abreviation of parallax of one second of arc. A unit of length (1pc=1E16 m), one parsec is defined to be the distance from the Earth to a star that has a parallax of 1 arcsecond.

Per Mil

Per thousand, often abreviated with a symbol simliar to a percentage sign with an extra o after the slash (o/oo).

Perihelion

The closest approach distance to the Sun for a given orbit.

Permafrost

Soil at or below the freezing point of water (0C or 32F) for two or more years.

Permineralized

Refers to fossils preserved by the infilling of empty spaces of an organism with minerals (commonly silica, calcite, or pyrite). The original organic and/or inorganic structures of such fossils are NOT replaced, but rather are surrounded by and infused with minerals. A more common--though now out of favor--term for permineralization is petrification. The types of organisms generally preserved by permineralization include microorganisms, plants, and fungi.

pH

The symbol "pH" refers to a scale of acidity for liquids. The thermodynamic definition is pH = - log(a), where "log" is a base-10 logarithm and "a" represents the thermodynamic activity of hydrogen ion (actually hydronium, H3O+). For most work done under conventional laboratory conditions, the definition reduces to pH = -log[H+] where "[H+]" is hydrogen ion (actually hydronium, H3O+) concentration in units of moles per liter. Although the latter definition is the simpler of the two, for some environments met in bioastronomy the former is needed for accuracy. Acidic solutions are taken as having pH < 7, alkaline (basic) ones as having pH > 7, and neutral ones as having pH = 7.

Phased Array

A type of interferometer in which the signals from all the individual telescopes are added together in such a way as to make them point at one direction in the sky, producing the small field of view of a single large telescope with a diameter equal to the longest baseline between any two telescopes of the interferometer.

Phosphite

HPO3=, the anion of phosphorous acid, H3PO3, with phosphorus in a reduced oxidation state (3+) relative to orthophosphate.

Photometric

A night is defined as photometric if there are no clouds and the absolute brightness of celestial objects may be measured and their brightnesses calibrated.

Photometry

Measurement of apparent brightness of an astronomical object (typically in the form of magnitude or flux).

Photomultiplier Tube Pixels

A photomultipier tube is a device that multiplies and converts photons to an electrical signal.

Phyllosilicate

Phyllosilicates are a type of structural silicates and typically parallel sheets of silicate tetrahedra (Si2O5). Common examples include clay minerals, serpentine and micas.

Phyllosilicate Texture

Phyllosilicate minerals form as sheets of Si and O atoms, resulting in flat, platy mineral form. A phyllosilicate texture may indicate that the rock has been recrystalled under high pressure and temperature (metamorphism).

Phylogenetic

Relating to or based on evolutionary development or history.

Phylogeny

1. The evolutionary development and history of a species or higher taxonomic grouping of organisms. Also called phylogenesis. 2. The evolutionary development of an organ or other part of an organism.

Phylum

A primary division of a kingdom, as of the animal kingdom, ranking next above a class in size.

Planetary Nebula

A planetary nebula has nothing to do with planets. A planetary nebula is the (often shapely) result of the death throes of a Sun-like star. The star swells to an enormous size and ejects its outer atmosphere to form the nebula (e.g. Cateye Nebula, Hourglass Nebula). The process generally leaves a relatively faint & compact object called a white dwarf at the center of the nebular structure.

Planetesimals

Rocky objects with sizes of a few kilometers. Planetesimals are formed through sticking and growth of dust particles in the original gaseous disk around a star.

Polychromatic

Consisting of many colors. In astronomy it refers to the ability to observe a wide range of frequencies at one time.

Polycyclic Aromatic Hydrocarbon

Abbreviated as PAHs, these are relatively chemically stable compounds composed of numerous fused aromatic carbon rings (6-membered planar rings - see aromatic hydrocarbons). Such compounds are often found in organics-containing meteorites and comprise the bulk of terrestrial kerogens.

Polymerization

A chemical reaction in which two or more small molecules combine to form larger molecules that contain repeating structural units of the original molecules.

Polymorph

A mineral that is identical to another in chemical composition but has a different crystal structure. An example is hexagonal and cubic water ice.

Pom

Polyoxymethylene, a polymer of formaldehyde (H2CO)

Prebiotic

Of, relating to, or being chemical or environmental precursors of the origin of life (Prebiotic molecules); also : existing or occurring before the origin of life (Prebiotic conditions).

Precession

Change in the direction of the axis of a rotating object. There are two types of precession, torque-free and torque-induced.

Prokaryote

Cells that lack a membrane-bound nucleus; by contrast, in eukaryotes the chromosomal DNA is enclosed in a membrane to form a nucleus

Prompt Emission

Radiation process in which (1) a radical is produced by photodissociation of a parent molecule (e.g., OH from H2O) in excited state, and (2) the dissociation product emits promptly (within ~10 milliseconds) transiting to a lower energy level. When observed in comets, infrared prompt emission from OH can be used as an indirect means to study the parent (H2O) molecule.

Proplyd

A protoplanetary disk (proplyd) is a rotating disk of dense dust and gas surrounding a young newly formed star. Since the very first protoplanetary disks were seen in the Orion Nebula (a very massive molecular cloud), in the literature PROPLYDs refer just to this particular molecular cloud. For Astrobiology purposes, we can think PROPLYDs are the place were planets will be formed.

Proteins

Any of a large class of complex organic chemical compounds that are essential for life. Proteins play a central role in biological processes and form the basis of living tissues. They consist of long chains of amino acids connected by peptide bonds and have distinct and varied three-dimensional structures. Enzymes, antibodies, and hemoglobin are examples of proteins.

Proteomics

A new and evolving field of science that seeks to specify all the proteins produced by a cell in all types of situations and environments and to understand how they function. Because proteins are the product of information coded for in DNA, proteomics is closely allied to the study of the genome.

Proterozoic

Geologic time period from 2.5 to 0.54 billion years ago, the most recent subdivision of the Precambrian

Proto-Intelligence

Current state of humankind where the dominant paradigm is violence. Proto-intelligence is the evolutionary stage that precedes the Collective Intelligence in advanced civilizations. Also called protointelligence.

Protoplanet

A planet in the process of forming from material in a protoplanetary disk. Moon- to Mars-sized objects formed through collision and sticking of planetesimals

Protosolar Nebula

Rotating disk of gas, dust and ice, from which the solar system is originated.

Protostar

An object that forms by contraction out of the gas of a giant molecular cloud in the interstellar medium. The protostellar phase is an early stage in the process of star formation.

PSN

Protosolar nebula

Purine Bases

Purine is a heterocyclic aromatic organic compound, consisting of a pyrimidine ring fused to an imidazole ring. Purines make up one of the two groups of nitrogenous bases. Pyrimidines make up the other group. These bases make up a crucial part of both deoxyribonucleotides and ribonucleotides, and the basis for the universal genetic code.

Pyrimidine

Pyrimidine is a heterocyclic aromatic organic compound similar to benzene and pyridine, containing two nitrogen atoms at positions 1 and 3 of the six-member ring.

Pyrolysis-Gas Chromatography-Mass Spectrometry

Commonly abbreviated py-gc-ms. An analytical technique used to measure the composition of solid (generally insoluble) organic materials by thermally breaking (pyrolizing) them into smaller molecular fragments. Such fragments are then separated by use of a gas chromatographic (GC) column and analyzed by use of a mass spectrometer (MS).

Pyroxene

An important group of rock-forming silicate minerals found in many igneous and metamorphic rocks. They share a common structure comprised of single chains of silica tetrahedra and they crystalize in the monoclinic and orthorhombic system. The usually consist of a diavalent cation (e.g. Fe, Mg, Ca, etc.) with a SiO3.

Quartz

Quartz is the second most common mineral in the Earth''s continental crust. It is made up of a lattice of silica (SiO2) tetrahedra.

Racemic

Of or relating to a chemical compound that contains equal quantities of dextrorotatory and levorotatory forms and therefore does not rotate the plane of incident polarized light.

Racemization

Process in which a particular enantiomer is converted into its mirror-image counterpart.

Radiation

Electromagnetic radiation, e.g., light and other electromagnetic waves.

Radiation

Ionizing radiation, high-energy atomic particles and gamma and x rays that can damage issue.

Radiation

The rapid evolution of new families and species.

Radiation

Click to define

Raman Spectroscopy

A type of spectroscopy that measures frequency-shifted photons that have scattered off of a material (organic or inorganic) having been excited by laser light. The incident photons interact with the molecular bonds of the material (the bonds absorb energy from or impart energy to these photons, thus changing their frequency). The magnitudes of the frequency shifts are diagnostic of the types of bonds or molecular structures present.

Rayleigh Fractionation Processes

A process of crystallization which assumes that as soon as the mineral has crystallized into a solid, it is immediately removed from the melt liquid. Crystal removal can occur by several methods, the most common is gravitational settling to the bottom of the magma chamber. Also known as perfect fractional crystallization.

Rayleigh Scattering

The scattering of electromagnetic radiation by particles whose sizes are much smaller than the wavelength of the radiation.

Red Dwarf

The most common type of star. Characteristically, it is a small, cool, very faint, main sequence star whose surface temperature is under about 4,000 Kelvins.

Reddening - E(B-V)

The excess red light seen towards objects obscured by dust. Blue light is preferentially absorbed and scattered by dust relative to red light.

Redox

Oxidation-reduction reactions; describing chemical reactions that require electron transfer.

Redshift

Denoted by the letter "z", redshift quantifies the expansion rate of the Universe. Due to the expansion, objects are receding from Earth. The further away an object is the faster it is receding and, therefore, has a larger redshift. Due to the finite speed of light, the larger the redshift the further back in time we are viewing the object.

Reducing

A condition in which electrons are available to be added to an ion or molecule, reducing the positive charge. For example, the reduction of Fe3+ to Fe2+ by the addition of an electron. This process is the opposite of oxidation by which electrons are removed, resulting in the increase of the positive charge of the ion or molecule.

Reflectance Spectrum

The spectral energy distribution of sunlight diffusely reflected from a planetary surface or atmosphere across a region of the spectrum.

Reflectivity

General term given to the response of a solid surface to incident radiation as a function of wavelength - e.g. the fraction of light reflected versus wavelength. Grey objects reflect all wavelengths of light equally, whereas red objects reflect more light at longer wavelenghts than at short wavelengths.

Refractory

1. High temperature element or material, first to condense from gas, last to evaporate from solid. 2. Substance which remains solid in all temperature conditions available in a particular body of the solar system (ex. dust particles in a comet).

Resilient

The capacity of a system, potentially exposed to energetic stress to adapt, by resisting or changing in order to reach and maintain an acceptable level of functioning and structure.

Resonance

A dynamical state occurring when the ratio of the periods of two planets are approximately equal to the ratio of two integers. For instance, Saturn and Jupiter are said to be in a near 5:2 resonance since their orbital periods are approximately 30 and 12 years, respectively.

Respiration

Extracting energy by using chemio-osmotic processes to oxidize reduced substrates

Retrosynthesis

Retrosynthesis is a method for designing the organic chemical synthesis. It starts from the target molecule to the starting materials, namely in the opposite direction from the traditional organic synthesis design method. The retrosynthesis fragments the target molecule into the subtargets, which are then fragmented further, all the way to the starting materials.

Rhizosphere

The rhizosphere is the soil zone that surrounds and is influenced by the roots of plants.

Rhizosphere

Inter-phase between the soil and the plant''s root.

Rifampicin-Resistance

Rifampicin is a semisynthetic antibiotic that interferes with the synthesis of RNA and is used to treat bacterial and viral diseases. Rifampicin-resistance allows bacteria to grow despite the presence of the antibiotic.

Rio Scale

An analytical tool for assessing the veracity and significance of candidate SETI signals received on Earth.

Rna Polymerase (Rpase)

A polymerase that catalyzes the synthesis of a complementary strand of RNA from a DNA template, or, in some viruses, from an RNA template.

Rock

A rock is a naturally-occurring aggregate of one or more minerals. Rocks are classified as igneous, sedimentary, or metamorphic.

Rosetta

ESA mission to explore comet 67P/ Cheryumov-Gerasimenko. Launched in 2004, it will reach the comet in 2014. An orbiter will follow the comet during one year, and a lander (Philae) will perform in situ analyses on the comet nucleus surface.

Rotational Spectrum

When excited above their lowest energy state, rotating molecules emit radiation. This radiation is related to the mass and structure of the molecule giving a characteristic pattern of spectral lines.

San Marino Scale

An analytical tool for assessing the potential impact of Active SETI signals transmitted from planet Earth.

Scalemic

Any non-racemic chiral substance.

Scattering Model

Model calculated with radiative transfer theory to describe quantitatively the diffuse reflectance of (usually) sunlight from a planetary surface or atmosphere. Scattering models are used to calculate synthetic spectra by incorporating the spectral distribution of the illuminating light and the optical properties of the reflecting surface

Schmidt Telescope

Wide angle photographic telescope, using a spherical mirror with a correcting lens to increase the field of view.

Sedimentary

Sedimentary rocks are cemented (lithified) sediments derived from pre-existing rocks, or they may be directly precipitated from solution (e.g., limestone).

Semimajor Axis

Average distance from the Sun for a given orbit.

Sensitivity

The sensitivity of an observation is a measure of how faint a signal can be detected. Improved sensitivity can generally be obtained by using a larger telescope, observing for longer times, or employing filters in frequency or time that exclude unwanted noise.

Serine

One of the 20 amino acids that is a common constituent of many proteins.

Serpentine

Serpentine is a group of common rock-forming hydrous magnesium iron phyllosilicate ((Mg, Fe)3Si2O5(OH)4) minerals; it may contain minor amounts of other elements including Al, Cr, Mn, Co and Ni. In mineralogy and gemology, serpentine may refer to any of 20 varieties belonging to the serpentine group.

SETI

An acronym denoting the Search for Extraterrestrial Intelligence. These are generally efforts to eavesdrop on radio or light signals sent by other intelligence in the cosmos.

Siderophors

A molecular receptor that binds and transports iron. (Source: McGraw-Hill Dictionary of Scientific and Technical Terms)

SIDP

Stratospheric Interplanetary Dust Particle.

Silicate

A class of minerals consisting primarily of silicon and oxygen and one or more metals (e.g., Ca, Na, Fe, Mg, etc.). Common silicate mineral groups include feldspars, pyroxenes, olivines, clay minerals, and quartz.

SMD

Space Mission Directorate

Snow Line

A region around the Sun or other star beyond which water freezes and cannot exist in liquid form. Also known as snowline

Solar Wind Plasma

The solar wind plasma consists primarily of high energy electrons and protons that are ejected from the upper atmosphere of the Sun.

Solid State C-13 Nmr

This method is used to study the chemical composition of the solid organic materials, such as the insoluble organic materials on meteorites or from the Maillard reaction.

Space Weathering

The interaction of the sun''s plasma (solar wind) with the surfaces of airless bodies (e.g. asteroids, the Moon) that results in the transformation of the original minerals into glassy material with interstitial metal blebs (Fe-Ni). This process makes the reflectance spectra more flat and redder than it would be so that the asteroid no longer resembles its daughter meteorites.

Spatial Resolution

A measure of the smallest separation between points that can be discriminated. Better spatial resolution permits an astronomer to study finer details on the sky and can be achieved by using a single telescope with a larger diameter, or an interferometer with the individual telescopes separated over a larger distance.

Spectral Imaging Correlator

A piece of instrumentation used with an interferometer that multiplies together the signals from every pair of telescopes to form a radio-image over a field of view that is determined by the size of the individual telescopes and with a spatial resolution determined by the longest baseline between any pair of antennas. Every pixel of the radio-image will have a number of frequency channels that is determined by the complexity of the electronics in the correlator, but is typically on the order of 1000.

Spectral Line Survey

Obtaining radio astronomical data over a wide frequency range from many individual observations

Spectrometer

A device for measuring the intensity of radiation absorbed, reflected, or emitted by a material as a function of wavelength.

Spectropolarimetry

The wavelength dependence of polarization - spectroscopy combined with polarimetry.

Spectroscopic Orbit

The orbital solution for a star derived from the radial velocities along the line of sight to the star. The radial velocities are determined from Doppler shifts in the spectrum of the star. Normally the inclination of the orbit to the line of sight is unknown, unless there is an eclipse (transit) or astrometric information. Without the orbital inclination, there is an ambiguity for a spectroscopic orbit with low velocity amplitude: the companion may have very little mass, or the orbit may be viewed nearly face on.

Stable Equilibrium

A condition in which all acting influences are canceled by others, resulting in a stable, balanced, or unchanging system.

Starshade

A 16 petal occulter developed by University of Colorado's Dr. Webster Cash. The starshade is used like a coronagraph in space, along with a space based telescope for the mission New Worlds Observer. This mission (which is still in proposal form) will diffract light in such a way that it deconstructively interferes with itself, enabling small terrestrial planets to be imaged and their atmospheres analyzed. This mission has the potential to detect plant life on an exoplanet! This mission will also discover and image a plethora of new exoplanets, providing scientist with valuable knowledge on the formation of planets and solar systems.

Stellar Companion

A memebr of a dual-star (binary) system.

Stellar Magnitude

Measure of the brightness of a star

Strecker

Refers to a method of synthesizing racemic mixtures of alpha-amino acids, as reported by Adolph Strecker (1822-1871); starting materials are an aldehyde or ketone and ammonium cyanide (or NH3 and either HCN or a cyanide salt).

Strecker Degradation Of Amino Acids

One of the steps in the Maillard reaction (see Maillard reaction).

Stress

Internal distribution of force per unit area that balances and reacts to external loads applied to a body.

Sublimation

Process of a solid phase transforming directly to a gas phase.

Sulfate

A class of evaporite minerals composed primarily of sulfur and oxygen (SO4), plus one or more metals (e.g., Ca, Na, Mg, Fe, etc.). Epsomite, gypsum, and anhydrite are common sulfate minerals.

Super-Earth

A terrestrial world greater than 1 Earth mass but no larger than about 5 Earth masses. The physical characterization of such worlds will be a challenge for Astrobiology.

Supernova

A stupendous stellar explosion -- the death throes of a star much more massive than our sun that spews heavier elements needed for life out into the galaxy and that sends out shock waves that can trigger the birth of new stars.

Synodic

The adjective synodic refers to the time needed for an object to return to the same position in the sky, as seen from the Earth. An object's synodic period is not the same as its sidereal period. For example, Jupiter returns to the same position in the Earth's sky in about 12 months (synodic period), but requires about 12 years (sidereal period) to orbit the Sun once and return to the same position relative to the Sun and other stars of the Milky Way.

Tectonic

Relating to, causing, or resulting from structural deformation of the earth's crust.

Teraflop

The acronym "flop" stands for a "floating point operation" of a computer, so a teraflop is a trillion (million, million) flops. One application in astrobiology is in the comparison of computer performance for data processing, such as in SETI programs.

Terrestrial

Resembling the Earth, such as the rocky objects Mercury, Venus, Earth, Mars, and Moon, which are often referred to as terrestrial bodies.

Terrestrial

Referring to the Earth, as in the phrase terrestrial life vs alien life.

Terrestrial

Associated with the land area of the Earth, as in the distinction between terrestrial and marine life.

TES

Thermal Emission Spectrometer (TES) aboard the Mars Global Surveyor spacecraft, which launched in November 1996 and arrived at Mars in September 1997. The TES interferometer measures within the thermal infrared, from 6-50 microns (~1650-200 cm-1) with 5 and 10 cm-1 spectral sampling.

Themis

Thermal Emission Imaging System, aboard the Mars Odyssey spacecraft which launched in April 2001 and arrived at Mars in October 2001. THEMIS combines a 5-wavelength visual system with a 9-wavelength infrared imaging system.

Theory

1. Conjecture, hypothesis, or speculation that is not factual in nature 2. Body of knowledge or practice, as in music theory or number theory 3. Broadly-based and well-supported scientific explanation; similar to a scientific law but usually less mathematical and of broader application, as in the theory of plate tectonics, theory of relativity, or theory of evolution.

Thermal Inertia

A measure of how much heat the upper 10-15 cm of a surface can store during the day and re-radiate at night. It is primarily dependent upon the physical properties of the surface (e.g., particle size, degree of induration, rock abundance).

Thioformaldehyde

H2CS

Tholin

Complex organic solid produced by energy deposition in cosmically abundant materials. Titan tholin was first produced by corona discharge in a gaseous mixture of methane and nitrogen to simulate photochemical processes in Titans atmosphere. Titan tholin and other tholins consist of amorphous and unstructured carbon, carbon nitrides, aromatic structures with varying degrees of order, aliphatic structures (small side chains and bridging units), and a wide array of other molecular structures.

Tholins

Titan aerosol analogues. Tholins consist of hundreds of organic molecules with the general formula CxHyNz. They are formed by UV photolysis and/or charged particle irradiation.

Tidal Heating

is the heating of the interior of one planetary body caused by stresses induced from the gravitational pull of another.

Tidal Locking

Tidal locking makes one side of an astronomical body always face another; for example, one side of the Earth''s Moon always faces the Earth. A tidally locked body takes just as long to rotate around its own axis as it does to revolve around its partner. This synchronous rotation causes one hemisphere constantly to face the partner body. Usually, only the satellite becomes tidally locked around the larger planet, but if the difference in mass between the two bodies and their physical separation is small, both may become tidally locked to the other, as is the case between Pluto and Charon.

Transcribed Genes

A gene is a section of DNA which contains the ''instructions'' on how to make a protein. Proteins, which include enzymes involved in metabolism and structural elements such as actin and myocin in muscle, do most of the work in a cell. When a protein is needed by the cell the appropriate gene is activated and its coding sequence is copied in a process called transcription, producing an RNA copy of the gene''s information. This RNA can then direct the synthesis of the protein in a process called translation. So a transcribed gene is one which has been activated to have an RNA copy made of it so its protein product can be made and used.

Transit Photometry

Transit photometry is a technique for detecting and studying extrasolar planets. Measurements are made of the brightness of a star with suspected planets as the latter pass in front of (transit) the star. The measurements are compared to those taken when the star and planets are in different relative positions.

Transit Spectroscopy

Transit spectroscopy is a technique designed to study the atmospheres of extrasolar planets. Spectral measurements are made of a star with suspected planets as the latter pass in front of (transit) the star. The measurements are compared to those taken when the star and planets are in different relative positions.

Transiting Planet

If the orbit of the planet around its host star is viewed edge on, then the planet may transit between the observer and the star, producing a dip in the light curve. Transiting planets are important because they establish the inclination of the orbit to the observer''s line of sight, which allows a determination of the actual mass of the panet. The amount of light blocked gives the size of the planet. Together the mass and radius give the density and thus information about the nature of the planet.

Transmembrane

Passing or occurring across a membrane.

Trimethylsilyl

Three methyl groups (i.e. Carbon bonded with three hydrogens :-CH3 ) bonded to a silicon atom.

True Polar Wander

Reorientation of the rotation axis of a planet relative to the surface geography due to mass redistribution. To be distinguished from apparent polar wander, which is due to plate tectonics.

Tryptophan

Tryptophan is an amino acid essential in human nutrition. It is one of the 20 amino acids encoded by the genetic code (as codon UGG).

Ubvri

One of many standard photometric systems in astronomy. Typically defined by the bandpasses of filters, the U band is in the blue-ultraviolet part of the spectrum, the B-band is blue, V-band is visual (wavelength centered near 0.55 microns), R is centered toward the red end of the optical portion of the spectrum, and I goes into the near infra-red.

Unstable Equilibrium

An equilibrium state of a system in which any departure of the system from equilibrium gives rise to forces or tendencies moving the system further away from equilibrium

Urea

An organic compound with the structural formula H2N-C(=O)-NH2 and empirical formula CH4N2O.

Urease

Urease is an enzyme that catalyzes the hydrolysis of urea into carbon dioxide and ammonia.

UTTR

Utah Test and Training Range. Military area in northern Utah and the landing site for the Stardust spacecraft.

UV

Ultra-violet light

UVB

Electromagnetic radiation closely related to visible light, but with a shorter wavelength, usually taken as 280-320 nm. UVB is emitted by the Sun by mostly absorbed by the atmospheric ozone layer before it reaches the ground. UVB is strongly absorbed by DNA and by proteins, damaging them. The ozone layer can be damaged by anthropogenic compounds and indirectly by astrophysical ionizing radiation sources.

Variable Stars

Variable stars are those with brightness fluctuations due to, for example, expansion and contraction, rotation, or being eclipsed by a nearby object. One class of interest to astrobiologists are the T Tauri stars, thought to be young objects. Their variations are due, at least in part, to dusty orbiting circumstellar material.

Volatile

(volatile substance): Molecule or atom that sublimates at relatively low temperature (i.e. cometary ices).

Voltammetric

The measurement of the potential energy per unit charge.

Voltammetry

Electrochemical technique applying a voltage potential to a working electrode and measuring current proportional to concentration of the analyte present

White Dwarfs

A white dwarf object is a final stage of evolution for stars of low and medium mass (about 0.5 - 9 solar masses). A white dwarf has a very high density since its mass can equal that of the Sun while its volume is comparable to that of the Earth. Type Ia supernovae are thought to arise from interactions involving a white dwarf that gravitionally attracts material from a nearby giant star.

Xanes

X-ray Absorption Near Edge Structure (XANES) is a type of absorption spectroscopy. XANES spectra indicate the absorption peaks due to the photoabsorption cross section in the X-ray Absorption Spectra. XANES was used to determine the nature of the chemical bonding of C, N, and O of organic material embedded in Stardust particles.

Zircon

Zircon is a mineral belonging to the group of nesosilicates. Its chemical name is zirconium silicate and its corresponding chemical formula is ZrSiO4. Uranium is often a trace element in zircon, making these minerals value for the dating of the formation of the igneous rock from which they formed.

Zodiacal Light

The Sun''s light reflected off of Solar System dust. The dust is primarily in the same plane as the planets and the result of asteroid-asteroid collisions and comet erosion.

Zwitterion

A zwitterion is a molecule that, while neutral overall, contains separate atoms with formal positive and negative charge. The zwitterionic character of molecules influences their chemical reactions. Amino acids are probably the most-important zwitterions for astrobiology.