image of the planet Earth
Department of Defense
Federal Aviation Administration
Department of Commerce
Department of the Interior
Federal Communications Commission
U.S. Department of Agriculture
National Science Foundation
Department of State
Department of Energy
Smithsonian Instution
Arms Control and Disarmament Agency
Environmental Protection Agency
U.S. Information Agency
ACDA Arms Control and Disarmament Agency
ACTS Advanced Communications Technology Satellite
AMASS Airport Movement Area Safety System AMOS Air Force Maui Optical Site
AMS Alpha Magnetic Spectrometer
APEC Asia-Pacific Economic Cooperation
ARS Agricultural Research Service (USDA)
ASDE Air Surface Detection Equipment (Model)
ASTP Apollo-Soyuz Test Project
ATLAS Atmospheric Laboratory for Applications and Science
AVHRR Advanced Very High Resolution Radiometer
AVIRIS Airborne Visible and Infrared Imaging Spectrometer


Black hole A completely collapsed, massive dead star whose gravitational field is so powerful that no radiation can escape from it; because of this property, its existence must be inferred rather than recorded from radiation emissions BLM Bureau of Land Management (DoI)


CASTLeS CfA-Arizona Space Telescope Lens Survey
CEOS Committee on Earth Observation Satellites
CfA Center for Astrophysics (Harvard-Smithsonian)
CIS Commonwealth of Independent States
CNES Centre Nationale d'Etudes Spatiales (France)
COPUOS Committee on the Peaceful Uses of Outer Space (United Nations)
Corona The outer atmosphere of the Sun, extending about a million miles above the surface
Cosmic rays Not forms of energy, such as x-rays or gamma rays, but particles of matter
COSPAR Committee on Space Research
CRISTA-SPAS Cryogenic Infrared Spectrometers and Telescopes for the Atmosphere-Shuttle Pallet Satellite
CUE Collaborative Ukrainian Experiment


DARS Digital Audio Radio Service
DMSP Defense Meteorological Satellite Program—DoD's polar-orbiting weather satellite system
DoC Department of Commerce
DoD Department of Defense
DoE Department of Energy
DoI Department of the Interior
DoS Department of State
DoT Department of Transportation
DSP Defense Support Program


EELV Evolved Expendable Launch Vehicle
El Niño A warm inshore current annually flowing south along the coast of Ecuador around the end of December and extending about every 7 to 10 years down the coast of Peru
EOS Earth Observing System—a series of satellites, part of NASA's Earth Science Enterprise, being designed for launch at the end of the 1990's to gather data on global change
EOSDIS Earth Observing System Data and Information System
EPA Environmental Protection Agency
EPIC Environmental Photographic Interpretation Center (EPA)
EROS Earth Resources Observation System (USGS)
ESA European Space Agency
ET External Tank
EUMETSAT European Organisation for the Exploitation of Meteorological Satellites
EVA Extravehicular activity


FAA Federal Aviation Administration
FAS Foreign Agricultural Service (USDA)
FCC Federal Communications Commission
Fly-by-light The use of light signals to connect the pilot's control devices with the aircraft control surfaces; or the use of light (fiber optic) control connections with no mechanical backup linkages and providing the pilot direct control of aircraft motion rather than control surface position
Fly-by-wire The use of electrical signals to connect the pilot's control devices with the aircraft control surfaces; or the use of electrical control connections with no mechanical backup linkages and providing the pilot direct control of aircraft motion rather than control surface position
FPI Fire Potential Index
Free flight A concept being developed by the FAA and the aviation community in which pilots could ultimately choose their own routes, speeds, and altitudes in flight, thus improving safety, while saving fuel, time, and natural resources
FSA Farm Service Agency (USDA)
FSS Fixed Satellite Service
FY Fiscal year


Gamma rays The shortest of electromagnetic radiations, emitted by some radioactive substances
GBS Global Broadcast Satellite Service
Geostationary Traveling around the Earth's equator at an altitude of at least 35,000 kilometers and at a speed matching that of the Earth's rotation, thereby maintaining a constant relation to points on the Earth
Geosynchronous geostationary
GHz Gigahertz
GIS Geographic Information System
GOES Geostationary Operational Environmental Satellite
GPS Global Positioning System


Heliosphere The region of the Sun's influence, including the Sun and the interplanetary medium
HST Hubble Space Telescope
Hypersonic Faster than Mach 4; faster than "high speed"
Hyperspectral An instrument capability using many very narrow spectral frequency bands (300 or more), enabling a satellite-based passive sensor to discriminate specific features or phenomena on the body being observed (such as Earth)


IGEB International GPS Executive Board
INMARSAT International Mobile (formerly Maritime) Satellite Organization
InSAR Interferometric Synthetic Aperture Radar
INSAT Indian Remote Sensing Satellite
Integrated modular avionics Aircraft-unique avionics cabinet that replaces multiple black boxes with shared common equipment and generic software
INTELSAT International Telecommunications Satellite Organization
Interferometry The production and measurement of interference from two or more coherent wave trains emitted from the same source
Internet An international computer network that began about 1970 as the NSF Net; very slowly it became a collection of more than 40,000 independently managed computer networks worldwide that have adopted common protocols to permit the exchange of electronic information
Ionosphere That region of Earth's atmosphere so named because of the presence of ionized atoms in layers that reflect radio waves and short-wave transmissions
ISS International Space Station
ITA International Trade Administration


K-band Radio frequencies in the 20-GHz range
Ka-band Radio frequencies in the 30-GHz range
Ku-band Radio frequencies in the 11–12-GHz range


Landsat Land [remote sensing] Satellite—a series of satellites designed to collect information about Earth's natural resources
Laser Light amplified by simulated emission of radiation—a device that produces an intense beam of light that may be strong enough to vaporize the hardest and most heat-resistant materials, first constructed in 1960
LDEF Long-Duration Exposure Facility
LEO Low-Earth orbit—100 to 350 nautical miles above Earth
LIDAR Light Intersection Direction and Ranging


Mach A relative number named after Austrian physicist Ernst Mach (1838–1916) and indicating speed with respect to that of sound in a given medium; in dry air at 32 degrees Fahrenheit and at sea level, for example, Mach 1=approximately 741 miles per hour (1,192 kilometers per hour)
Magnetosphere The region of Earth's atmosphere in which ionized gas plays an important role in the atmospheric dynamics and where, consequently, the geomagnetic field also exerts an important influence; other magnetic planets, such as Jupiter, have magnetospheres that are similar in many respects to Earth's
MilSatCom Military Satellite Communications
MOU Memorandum of Understanding
MTCR Missile Technology Control Regime


NAPP National Aerial Photography Program NAS National Airspace System (FAA)
NASA National Aeronautics and Space Administration
NASDA National Space Development Agency (of Japan)
NASS National Agricultural Statistics Service (USDA)
NCAP National Civil Applications Program (USGS)
NDOP National Digital Orthoquad Program
NESDIS National Environmental Satellite, Data, and Information Service (NOAA)
Neutron star Any of a class of extremely dense, compact stars thought to be composed primarily of neutrons; see pulsar
NIST National Institute of Standards and Technology (DoC)
NOAA National Oceanic and Atmospheric Administration (DoC); also the designation of that administration's Sun-synchronous satellites in polar orbit Nominal Functioning as designed
NOx Nitrous oxide
NPOESS National Polar-orbiting Operational Environmental Satellite System
NRCS National Resources Conservation Service (USDA)
NRO National Reconnaissance Office
NSF National Science Foundation
NTIA National Telecommunications and Information Administration (DoC)—the Federal Government's radio spectrum manager, which coordinates the use of LEO satellite networks, such as those for Landsat, Navstar GPS, the Space Shuttle, and the Television and Infrared Operational Satellite (TIROS), with other countries of the world


OASC Office of Air and Space Commercialization (DoC)
OAST Office of Aeronautics and Space Technology (former NASA office)
ODERACS Orbital Debris Radar Calibration Spheres
OLMSA Office of Life and Microgravity Sciences and Applications (NASA)
Order of magnitude An amount equal to 10 times a given value; thus if some quantity was 10 times as great as another quantity, it would be an order of magnitude greater; if 100 times as great, it would be larger by two orders of magnitude
ORFEUS-SPAS Orbiting and Retrievable Far and Extreme Ultraviolet Spectrograph-Shuttle Pallet Satellite
OSS Office of Space Science (NASA)
OSTA Office of Space and Terrestrial Applications (former NASA office)


PAMS-STU Passive Aerodynamically Stabilized Magnetically Damped Satellite-Satellite Test Unit
Pathfinder A program that focuses on the processing, reprocessing, maintenance, archiving, and distribution of existing Earth science data sets to make them more useful to researchers; NASA, NOAA, and USGS are involved in specific Pathfinder efforts
PCB Polychlorinated biphenyl
Photogrammetry The science or art of obtaining reliable measurements by means of photography
POES Polar-orbiting Operational Environmental Satellite (program)
PPS Precise Positioning Service
Pulsar A pulsating radio star, which is thought to be a rapidly spinning neutron star; the latter is formed when the core of a violently exploding star, called a supernova, collapses inward and becomes compressed together; pulsars emit extremely regular pulses of radio waves


Quasar A class of rare cosmic objects of extreme luminosity and strong radio emission; many investigators attribute their high-energy generation to gas spiraling at high velocity into a massive black hole


Ramjet A jet engine with no mechanical compressor, consisting of specially shaped tubes or ducts open at both ends, along with the air necessary for combustion being shoved into the duct and compressed by the forward motion of the engine
RAPID Repair Assessment Procedure and integrated Design (software)
Radarsat Canadian radar satellite
RSA Russian Space Agency
RSML Remote Sensing and Modeling Laboratory (ARS)


SAO Smithsonian Astrophysical Observatory
SAR Synthetic Aperture Radar
SBIRS Space Based Infrared System
SBS Satellite Business Systems
Scramjet Supersonic-combustion ramjet
SeaWiFS Sea-viewing Wide Field-of-view Sensor
SLS Spacelab Life Sciences
SNOE Student Nitric Oxide Experiment
SOFIA Stratospheric Observatory for Infrared Astronomy
Solar wind A stream of particles accelerated by the heat of the solar corona (outer region of the Sun) to velocities great enough to permit them to escape from the Sun's gravitational field
SPACEHAB Commercial module for housing Shuttle experiments
SPARTAN Shuttle Pointed Autonomous Research Tool for Astronomy
SPOT Satellite Pour l'Observation de la Terre (French satellite for the observation of Earth)
SRB Solid Rocket Booster
SRM Solid Rocket Motor
SRMU Solid Rocket Motor Upgrade
SSBUV Shuttle Solar Backscatter Ultraviolet
SSCE Solid Surface Combustion Experiment
SSME Space Shuttle Main Engine
SSTI Small Satellite Technology Initiative
START Strategic Arms Reduction Treaty
STS Space Transportation System


TDRS Tracking and Data Relay Satellite
TM Thematic Mapper (Landsat instrument)
TRACE Transition Region and Coronal Explorer
TRMM Tropical Rainfall Measuring Mission
TSA Technical Safeguard Agreement


UARS Upper Atmosphere Research Satellite
UHF Ultrahigh Frequency—any frequency between 300 and 3,000 megacycles per second
U.S. United States
USDA U.S. Department of Agriculture
USGS U.S. Geological Survey (DoI)
USIA U.S. Information Agency
USIS U.S. Information Service (USIA abroad)
USML U.S. Microgravity Laboratory
USMP U.S. Microgravity Payload
USSR Union of Soviet Socialist Republics (former)


VAAC Volcanic Ash Advisory Center
VHF Very High Frequency—any radio frequency between 30 and 300 megacycles per second


WAAS Wide Area Augmentation System
WARP Weather and Radar Processor (program)
Wind shear Variation of wind speed and wind direction with respect to a horizontal or vertical plane; powerful but invisible downdrafts called microbursts focus intense amounts of vertical energy in a narrow funnel that can force an aircraft to the ground nose first if the aircraft is caught underneath
WSF Wake Shield Facility
WTO World Trade Organization


X-rays Radiations of very short wavelengths, beyond the ultraviolet in the spectrum

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