Glossary

 AAS
American Astronomical Society
 ACMA
Atmospheric Composition Modeling and Analysis
 ADP
Astrophysics Data Analysis program
 AFL
Astrobiology Field Laboratory
 AGN
Active Galactic Nuclei
 AGU
The American Geophysical Union
 AIRS
Atmospheric InfraRed Sounder
 AIST
Advanced Information System Technology
 AIST
Advanced Information Systems Technology program
 AMSU
Advanced Microowave Sounding Unit
 AO
Announcement of Opportunity
 AOR
Authorized Organizational Representative. NASA proposals (through NSPIRES) are not submitted by individual scientists, engineers or educators, they come from an institution (such as a university). The Authorized Organizational Representative must be an official representative of that university (for example) who has the authority to approve overhead rates in the budget, etc
 APRA
Astronomy and Physics Research and Analysis
 ASTID
Astrobiology Science and Technology Instrument Development and Mission Concept Studies
 ATFP
Astrophysics Theory and Fundamental Physics program
 ATI
Advanced Technology Initiative
 AVGR
Ames Vertical Gun Range
 Acoustic Sounders
Instruments that acquire multispectral measurements from which vertical profiles of atmospheric temperature and humidity can be derived and does particular measurements of depth of water below an instrument (at the surface or at some moored depth) which is computed form the travel time of the acoustic pulse emitted by this sounder.
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 altimetry
An aneroid barometer designed to register changes in atmospheric pressure accompanying changes in altitude
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 assimilation
the incorporation or conversion of nutrients into protoplasm that in animals follows digestion and absorption and in higher plants involves both photosynthesis and root absorption
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 asteroids
Metallic, rocky objects without atmospheres that orbit the Sun, but are too small to be called planets.
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 atmospheric
The air surrounding the Earth, described as a series of shells or layers of different characteristics. The atmosphere, composed mainly of nitrogen and oxygen with traces of carbon dioxide, water vapor, and other gases, acts as a buffer between Earth and the sun. The layers, troposphere, stratosphere, mesosphere, thermosphere, and the exosphere, vary around the globe and in response to seasonal changes.
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 auroral zone
The portion of the Earth that traverses the midnight portion of an oval is known as the auroral zone.
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