American Astronomical Society
Atmospheric Composition Modeling and Analysis
Astrophysics Data Analysis program
Astrobiology Field Laboratory
Active Galactic Nuclei
The American Geophysical Union
Atmospheric InfraRed Sounder
Advanced Information System Technology
Advanced Information Systems Technology program
Advanced Microowave Sounding Unit
Announcement of Opportunity
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
Astronomy and Physics Research and Analysis
Astrobiology Science and Technology Instrument Development and Mission Concept Studies
Astrophysics Theory and Fundamental Physics program
Advanced Technology Initiative
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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An aneroid barometer designed to register changes in atmospheric pressure accompanying changes in altitude
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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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Metallic, rocky objects without atmospheres that orbit the Sun, but are too small to be called planets.
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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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