Glossary
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AACS: Attitude and Articulation Control
AAS: American Astronomical Society
AAT: Anglo-Austrailian Telescope
AGB: Asymptotic Giant Branch
AGN: Active Galactic Nuclei
AGU: American Geophysical Union
Albedo: Reflectivity; the ratio of reflected light to incident
light. The fraction of sunlight that a body reflects.
ALOT: Adaptive Large Optics Technologies
AMSD: Advanced Mirror System Demonstrator
AO: Announcement of Opportunity
Aperture: The diameter of an opening; the diameter of the primary lens or mirror
of a telescope.
Apex: The point towards which a body is moving.
Aphelion: The point in orbit where a body is farthest from the Sun.
Apogee: The point in orbit where a body is farthest from Earth.
ARC: Ames Research Center
Arc minute: 1/60 of a degree.
Arc second: 1/3600 of a degree.
ASI: Italian Space Agency
ASIC: Application Specific Integrated Circuit
ASPEN: Autonomous Scheduling and Planning Environment
Asteroid Belt: A 1/2-AU-wide region between the orbits of Mars and Jupiter where
the most asteroids are found.
Astronomical Unit (AU): Unit of distance, equal to the distance of the Earth
from the Sun, about 150 million kilometers (93 million miles).
Astrophysics: That part of the astronomy dealing with the physics of astronomical
objects and phenomena.
ASWG: Ad hoc Science Working Group
ATIS: Automated Telescope Instruction Set
AU: Astronomical Unit (Earth orbital radius)
AURA: Association of Universities for Research in Astronomy
Azimuth: Motion around a vertical axis; for instance, a measure of position around
the horizon.
Backscattering: Reflecting light back in the direction of the source.
Bandpass: Wavelength range over which an observation is made.
This is measured in microns (one millionth of a meter) for the JWST. The JWST
will have near-infrared (NIR) bandpasses covering the wavelength range 1-5 microns
and possibly thermal-infrared (TIR) bandpasses as well, covering the range 5-30
microns.
Beryllium: A lightweight metallic element (symbol: Be, atomic number 4), present
in emerald and beryl stones. The JWST primary mirror will be made of beryllium.
Big Bang: The common term for the start of the universal expansion---when
all matter was clustered at the 'beginning' and it 'exploded.' This expansion
continues to the present day---galaxies are still moving apart from one another,
as measured by redshift.
Black Hole: An object whose gravity is so strong that the escape
velocity of light exceeds the speed of light.
BLIP: Background Limited Performance
BLR: Broad Line Region
Brown Dwarf: An object that is bigger than a planet but is too
small to ignite internal nuclear fusion.
C&TS: Command & Telemetry (Processing) System
Calibration: The process of adjusting an instrument so that
its reading can be correlated to the actual value being measured.
CCD: Charge Coupled Device
CCS: Control Center System (HST)
CDS: Correlated Double Sampling
CFHT: Canadian-French-Hawiian Telescope
CGRO: Compton Gamma Ray Observatory
Charon: The only known satellite of Pluto.
CMB: Cosmic Microwave Background
CNES: Centre National d'Etudes Spatiales
COBE: Cosmic Background Explorer
Comet: A small body of ice and dust in orbit around the Sun. While passing near
the sun, a comet's vaporized ice become its "tail"
Constellation: A group of stars that, from the vantage point
of Earth, appear to make a shape. They are often named after mythological characters,
people, animals, and things.
Convection: A transfer of heat energy by circulation through
a gas or liquid.
Corona: The Sun's outer atmosphere.
Coronagraph: An instrument used to block out the bright light from the sun or
other stars so that nearby faint objects are visible.
Cosmology: The study of the origin, evolution and structure of the universe (the
cosmos).
COSPAR: Committee on Space Research
COSTAR: Corrective Optics Space Telescope Axial Replacement (HST)
COTS: Commercial Off-The-Shelf
CPI: Continuous Process Improvement
Crater: A round impression left in a planet or satellite from
a meteoroid collision.
Cryogenic: Relating to extremely low temperatures.
CSA: Canadian Space Agency
CSC: Computer Sciences Corporation
DARA: Deutsche Agentur fur Raumfahrt-angelegenheiten
Dark matter: A form of matter which has not been directly observed
but whose existence has been deduced by its gravitational effects.
DCATT: Developmental Cryogenic Active Telescope Testbed
Density Wave: A kind of wave, similar to sound waves, induced
in a flat plane of a resisting medium (such as the rings of Saturn) by gravitational
forces, often assuming the form of a tightly wound spiral.
Design Reference Mission: The sample science program that is being used to help
define engineering parameters for the JWST. The DRM is made up of astronomical
targets, their brightnesses, space density, observing wavelength and resolution.
DFS: Dispersed-Fringe Sensor
DM: Deformable Mirror
DOF: Degree(s) of Freedom
Downlink: A radio connection wherein a spacecraft can communicate
to Earth.
DPU: Data Processing Unit
DQE: Detective Quantum Efficiency
DRM: Design Reference Mission
DS-1: Deep Space-1 mission
DS-4: Deep Space-4 mission
DSN: Deep Space Network (JPL)
DSP: Digital Signal Processor
Eccentric: Noncircular; elliptical (applied to an orbit).
ECF: European Coordinating Facility
Eclipse: When one celestial object moves into the shadow of
another.
EFOSC: ESO Faint Object Spectrograph & Camera
EGS: European Geophysical Society
Elevation: Angular distance above the horizon.
ESA: European Space Agency
ESO: European Southern Observatory
ESOC: European Space Operations Centre, Darmstadt (Germany)
ESRIN: ESA's Documentation and Information Centre (Italy)
ESTEC: European Space Research and Technology Centre, Noordwijk (The Netherlands)
EUV: Extreme Ultra-Violet
EXOSAT: European X-ray Observatory Satellite
Extrasolar Planet: Planets that orbit stars other than our own Sun.
Fault protection: A program built into a spacecraft which detects errors and
faults in the spacecraft before they become monstrous and fixes them or reroutes
to avoid them.
FD&C: Fault Detection and Correction
FES: Fine Error Sensor
FGS: The JWST Fine Guidance Sensor instrument. FGS will primarily
help to keep JWST pointed onto its target, but will also have tunable filters
to make astronomical observations.
FIRST: Far-Infrared and Sub-millimetre Space Telescope
FM: Flight Model
FOC: Faint Object Camera (HST)
Forward Scattering: Reflecting light approximately away from the source.
FOT: Flight Operations Team
FOV: Field of View
FPA: Focal Plane Array
FS: Fowler Sampling
FSM: Fast Steering Mirror
FSW: Flight Software
FWHM: Full Width at Half Maximum
FY: Fiscal Year
GAIA: Global Astrometric Interferometer for Astrophysics
Galaxy: A huge assembly of stars, gas and dust bound together
by gravity.
GCR: Galactic Cosmic Ray
General Relativity: The ideas developed by Albert Einstein that mass and energy
determine the geometry of spacetime and that the curvature of this spacetime
manifests itself as what we call gravitational forces.
Geo-: Prefix referring to the Earth.
Geocentric: Earth centered.
GGS: Global Geospace Science
GHRS: Goddard High Resolution Spectrometer (HST)
GINGA: Japanese X-Ray Satellite
Globular Cluster: A gravitationally bound system of several hundred thousand
to one million stars thought to have all formed at the same time.
GMT: Greenwich Mean Time
GOES: Geostationary Operational Environmental Satellite
GPS: Global Positioning System
Gravity: The force of attraction between masses.
GRB: Gamma Ray Burst
Great Red Spot: Jupiter's very large anti-cyclonic (high
pressure) storm, which is akin to a hurricane on Earth. Three Earths
would fit within its boundaries - and it has persisted for at least the 400 years
that humans have observed it through telescopes..
GRO: Gamma Ray Observatory (see CGRO)
GSFC: Goddard Space Flight Center
GTO: Geo-Transfer Orbit
Halley's Comet: A specific bright
comet, visible to the naked eye, whose path we can predict.
HARD: High Accuracy Reflector Development
HDF: Hubble Deep Field
Helio-: Prefix referring to the Sun.
Heliocentric: Centered on the Sun.
Hertzsprung-Russell Diagram: A graphical representation of the
classification of stellar types according to temperature and brightness. Physical
properties of stars are related to their position on the diagram. Therefore,
changes in the positions of stars on the diagram can be used to trace their evolution.
HGA: High Gain Antenna
HST: Hubble Space Telescope
HSTS: Heuristic Scheduling Testbed System
Hubble Constant: This number relates the distances of galaxies
to their recession velocity and represents the rate at which the universe is
currently expanding.
I/F: Interface
I&C: Instrumentation and Communication
I&T: Integration and Test
IAS: Institut d'Astrophysique Spatiale, Orsay (France)
IAU: International Astronomical Union
IDT: Investigation Definition Team
IFSI: Istituto Fisica Spazio Interplanetario (Italy)
IFTS: Imaging Fourier Transform Spectrometer
IGPP: Institute of Geophysics and Planetary Physics
IKI: Space Research Institute of the Russian Academy of Science
IMOS: Simulation platform for structural, optical & AACS/FSW
interactions
Inclination: Tilt or angle. When used with respect to an orbit, the angle between
the orbital plane of a revolving body and some fundamental plane, usually the
plane of the celestial equator.
Infrared: Electromagnetic radiation whose wavelength is longer than the longest
visible red but shorter than radio waves.
INTA: Instituto Nacional de Tecnica Aerospacial (Spain)
Interferometery: The location and examination of sources of electromagnetic radiation
through the simultaneous use of two or more separated telescopes. Interferometers
produce overlapping wave patterns from the radiation. These patterns are studied
to determine the brightness and angular structure of the emitting source.
Ion : An atom or molecular fragment that has a positive electrical charge due
to the loss of one or more electrons. The simplest ion is the hydrogen nucleus,
a single proton.
IPAC: Infrared Processing Analysis Centre
IR: Infrared
IPDT: Integrated Product Development Team
IPT: Integrated Product Team
IRAF: Image Reduction & Analysis Facility
IRAS: Infrared Astronomy Satellite
IRD: Interface Requirements Document
IRMB: Institut Royal Meteorologique de Belgique
ISAS: Institute of Space and Astronautical Science (part of the Japanese Aerospace Exploration Agency)
ISIM: Integrated Science Instrument Module
ISIS: Inflatable Sunshield in Space
ISM: Interstellar Medium
ISO: Infrared Space Observatory
ITAR: International Traffic in Arms Regulations
IUE: International Ultraviolet Explorer
IUEFA: IUE Final Archive
JAXA: Japan Aerospace Exploration Agency
JCMT: James Clerk Maxwell Telescope
Jovian Planet: Any of the four biggest planets: Jupiter, Saturn, Uranus, and
Neptune.
JPL: Jet Propulsion Laboratory
JSC: Lyndon B. Johnson Space Center
JWST: James Webb Space Telescope
Kelvin: Absolute temperature scale measure. Absolute zero, or 0 Kelvin corresponds
to -273 degrees Celsius.
Kiloparsec (kpc): A disatance of one thousand parsecs (see: Parsec)
KSC: Kennedy Space Center
Kuiper Belt: A field of icy, comet-like bodies extending from
the orbit of Neptune out to about 7 billion miles (10 billion km) from the Sun.
Kuiper Belt Object (KBO): One of the icy, comet-like bodies residing
in the Kuiper Belt.
L2 Point: A location roughly 1.5 million km (1 million miles) in the anti-Sun
direction of the Earth. An object at the L2 point will tend to follow the Earth
as it goes around the Sun.
Lagrangian or Lagrange Point: Lagrange Points mark positions where the
gravitational pull of the two large masses precisely equals the centripetal force
required to rotate with them. Used for positioning satellites in space, where
minimum fuel will be required to maintain a stable orbit.
LAMP: Large Advanced Mirror Program
LaRC: Langley Research Center
LBV: Luminous Blue Variable
LDEF: Long Duration Exposure Facility
Leading Side: For a satellite that keeps the same face toward the planet, the
hemisphere that faces forward, into the direction of motion.
Light: Electromagnetic radiation. Commonly used to describe that which
is visible to the eye.
Light year: The distance light travels in a vacuum in one year; equal to 9.46x1015 meters.
LISA: Laser Interferometer Space Antenna
LMC: Large Magellanic Cloud
LMCo: Lockheed Martin Corporation
LMXRB: Low Mass X-ray Binary
LOS: Line of Sight or Loss of Signal
LPSP: Laboratoire de Physique Stellaire et Planetaire (France)
LTE: Local Thermal Equilibrium
Lunar: Referring to the moon.
Magnetic field: A region of space near a magnetized body where magnetic forces
can be detected.
Magnetopause: The boundary of the magnetosphere, lying inside the bow
shock.
Magnetosphere: The region surrounding a planet within which the planetary magnetic
field dominates and charged particles can be trapped.
MAP: Microwave Anisotropy Probe (now WMAP)
MAS: Milli-arcseconds
MDS: Mission Data System
Mean: Synonym for mathematical average.
Megaparsec (Mpc): One million parsecs (see: parsec)
Meteor: The luminous phenomenon seen when a meteoroid enters the atmosphere,
commonly known as a shooting star.
Meteorite: A part of a meteoroid that survives entry into the Earth's
atmosphere.
Meteoroid: A small rock in space.
MFSC: Marshall Space Fight Center
MHD: Magneto-hydrodynamics
Microdynamics: The physics of very small forces
Micron: A distance of 1/1,000,000th of a meter, roughly 1/25,000th of an inch.
(Also called a micrometer, abbreviated µm).
Mid Infrared: The the middle part of the range of infrared.
MIRI: The JWST Mid Infrared Instrument. MIRI will observe lower energy (longer
wavelength) light than the other instruments.
MLI: Multilayer Insulation
MMS: Matra Marconi Space, also Magnetospheric Multiscale Mission
MOS-CCD: Metal Oxide Semiconductor - Charge Coupled Device
MPE: Max-Planck-Institut fur Extraterrestrische Physik
MPI: Max-Planck-Institut (Germany)
MPS: Mission Planning and Scheduling system
MTF: Modulation Transfer Function
NASA: National Aeronautics and Space Administration
NASDP: NGST Adaptive Scheduler Demonstration Prototype
NCC: Network Control Center (NASA GSFC)
NEA: Noise Equivalent Angle
Near Infrared: The range of infrared radiation nearest to the range of human
vision.
NEPS: Noise Equivalent Point Source
Newton: A unit of force that is a size such that a body of one kilogram under
it effects would accelerate one meter per second per second.
NGC: New General Catalogue
NGST: Northrop Grumman Space Technology (JWST Observatory prime contractor).
Also, Next Generation Space Telescope (original name of JWST)
NICMOS: Near-Infrared Camera and Multi-Object Spectrometer (HST)
NIEL: Non-Ionizing Energy Loss
NIR: Near Infrared
NIRCam: The JWST Near Infrared Camera instrument. NIRCam will primarily
take "pictures" of
the sky.
NIRSpec: The JWST Near Infrared Spectrograph instrument. NIRSpec will
measure spectra of objects in the sky.
NLR: Narrow Line Region
NMSD: NGST Mirror System Demonstrator
NOAA: National Oceanographic and Atmospheric Administration
NOT: Nordic Optical Telescope
NRA: NASA Research Assignment
NRAO: National Radio Astronomy Observatory
NSI: NASA Science Internet
NSSDC: National Space Science Data Center (at GSFC)
OFLS: Off-Line System (AXAF)
Omega: In astronomy, omega is a dimensionless number that measures the
ratio of the density of the universe to the critical density (the density to
close the universe).
Oort Cloud: An as-yet undetected pool of small bodies in the outermost regions
of the Solar System, perhaps extending as much as 1/10th of a light year from
the Sun. Long-period comets are believed to originate in the Oort Cloud.
OPD: Optical Path Difference
OR: Observation Request
Orbit: The path of an object that is moving around a second object or point.
OS: Operating System
OTA: Optical Telescope Assembly
PAH: Polycyclic Aromatic Hydrocarbon
Parallax: The change in an object's apparent position when viewed from two different
locations.
Parsec (pc): Commonly used unity of distance for astronomy. Equal to 3.26 light years, it is actually the distance an object
would have to be from Earth for its parallax to be 1 second of arc.
PASS: POCC Applications Support Software (HST)
PCD: Photon Counting Detector
PEP: Proposal Entry Processor (HST)
Periapsis: Low point of an orbit.
Perturbation: A small disturbing effect
Phase angle: The angle in which waves come to a body.
Photometry: The measurement of light intensities.
Photon: a discrete packet of electromagnetic energy.
PI: Principal Investigator
Plasma: A fourth state of matter - not a sold, liquid, or gas. In a plasma, the electrons are pulled free from the atoms and can move independantl.
The individual atoms are charged, though the total number of positive and negative charges is equal, maintaining an overall electrical neutrality.
PLM: Payload Module
PM: Primary Mirror
PNAR: Preliminary Non-Advocate Review
POCC: Project Operations Control Center
Primitive: Used in a chemical sense, it indicates an unmodified material
representative of the original composition.
PROM: Programmable Read-Only Memory
PSF: Point Spread Function
QE: Quantum Efficiency
QPO: Quasi Periodic Oscillations
QSO: Quasi Stellar Object. They are intense, point-like sources of
radiation (often from radio through gamma rays), characterized by high redshifts.
The term QSO used to describe both radio-loud and radio-quiet classes of objects.
Quasar: Quasar is a contraction of "quasi stellar radio source". Since
it turns out that not all of the objects described as quasars are sources of
radio radiation, the term QSO was invented, to refer to both the radio-loud and
radio-quiet objects.
R&D: Research and Development
Radiation: Electromagnetic energy, photons
Radiation Belts: More intense regions of charged particles in a magnetosphere;
the belts contain ions and electrons.
RAL: Rutherford Appleton Laboratory (UK)
RAX: Remote Agent Experiment (DS-1)
Resolution: Ability to distinguish detail, usually expressed in terms of the
size of the smallest features that can be distinguished.
Resonance: In astronomy, a relationship in which the orbital period
of one body is related to that of another by a simple integer fraction, such
as 1/2, 2/3, 3/5.
Retrograde: Backwards; as applied to an orbit, moving in the opposite sense from
the great majority of solar system bodies.
Revisits: As a nound, the number of separate times that the JWST must observe a specific target
to accomplish science goals outlined in the Design Reference Mission
RF: Radio Frequency
RFP: Request For Proposals
RMS: Remote Manipulator System (Space Shuttle)
RPS-2: Remote Proposal Submission System - Second Generation (HST)
RQE: Responsive Quantum Efficiency
RTG: Radioisotope Thermal Generator
SAO: Smithsonian Astrophysical Observatory
SASC: Science Analysis Support Centre
Satellite: A body that revolves around a larger body.
SAX: Satellite per Astronomia in raggi X (Italy/The Netherlands)
SCA: Sensor Chip Array
SED: Spectral Energy Distribution
SERC: Science & Engineering Council (UK)
SES: Systems Engineering Simulator (JSC)
Shroud, Rocket: The fairing of the rocket that contains the payload. The limitations
of available shroud diameters has a direct impact on the size and packaging of
the JWST.
SI: Science Instrument
SIRTF: Space Infrared Telescope Facility (now Spitzer Space Telescope)
SMS: Science Mission Schedule
SN: Supernova
SNR: Supernova Remnant
SOC: Science Operations Centre
Solar Nebula: The large cloud of gas and dust from which the Sun and planets
condensed 4.6 billion years ago.
Solar Wind: The charged particles (plasma), primarily protons and electrons,
that are emitted from the Sun and stream outward throughout the solar system
at speeds of hundreds of kilometers per second.
SOT: Science Operations Team
Space Density: From the design reference mission: The expected frequency of objects
in space measured in number of objects per square minutes of arc on the sky.
Spacetime: A system for looking at the universe as one in which the three spatial
dimensions are unified with the time dimension.
Spectroscopy: The use of spectrum analysis.
Spectrum: A particular distribution of wavelengths or frequencies and energy.
A rainbow is a naturally-occurring spectrum of sunlight.
SPSS: Science Planning and Scheduling System (HST)
SR: Strehl Ratio
SSM: Space Support Module
ST-ECF: Space Telescope - European Coordinating Facility
STEP: Satellite Test of the Equivalence Principle
STIS: Space Telescope Imaging Spectrograph
STJ: Superconducting Tunnel Junction
STS: Space Transportation System
STScI: Space Telescope Science Institute
STSP: Solar Terrestrial Science Programme
Supernova: The explosion of a massive star
SUTR: Sample Up The Ramp
SWT: Science Working Team
SZ: Sunyaev-Zeldovich Effect
TDRS: Tracking and Data Relay Satellite
TDRSS: Tracking and Data Relay Satellite System
Telemetry: Radio signals from a spacecraft used to encode and transmit data to
a ground station.
TID: Total Ionizing Dose
TOO: Target of Opportunity
Torus: Solid geometrical figure with the shape of a doughnut or innertube.
TPF: Terrestrial Planet Finder
TRANS: Transformation expert system (HST)
TSU APT: Tennessee State University Automatic Photoelectric Telescopes
ULE: Ultra Low Expansion
Ultraviolet (UV): Electromagnetic radiation whose wavelength is shorter than visible
light but longer than X-rays.
VILSPA: Villafranca Satellite Tracking Station
Visible Light: Electromagnetic radiation whose wavelength is between 3.5x10-7
and 8.0x10-7 meters.
VLA: Very Large Array
VLBI: Very Long Baseline Interferometry
VRTX: Versatile Real Time Executive
VSIM: "Prescription Retrieval" software that measures alignment errors
VTT: Vacuum Tower Telescope
Wavelength: The distance between two successive peaks or troughs of a wave.
WCT: Wave Front Control Testbed
WFC: Wave Front Control
WFE: Wave Front Error
WFPC2: Wide Field Planetary Camera 2 (HST)
WFS&C: Wave Front Sensing & Control
WIRE: Wide-Field Infrared Explorer
WLI: White Light Interferometry
WMAP: Wilkinson Microwave Anisotropy Probe
WWW: World Wide Web
XMM: X-ray Multi-Mirror Mission (Cornerstone)
X-ray: High energy electromagnetic radiation with a wavelength of about 10-10
meters.
XTE: X-Ray Timing Explorer (now Rossi X-ray Timing Explorer or RXTE)
ZAMS: Zero Age Main Sequence
Zodiac: In astronomy, the region of the sky through which the planets are observed to move.
