- AAS
- American Astronomical Society
- ACMA
- Atmospheric Composition Modeling and Analysis
Atmospheric Composition Modeling and Analysis
- Acoustic Sounders
- acoustic sounder
- Acoustic Sounder
- acoustic sounders
- Acoustic sounder
- 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.
- 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 Systems Technology program
- altimetry
- Altimetry
- Altimeter
- altimeter
- An aneroid barometer designed to register changes in atmospheric pressure accompanying changes in altitude
- AMSU
- Advanced Microowave Sounding Unit
- AO
- Announcement of Opportunity
- AOR
- Authorized Organizational Representative
- 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
- assimilation
- 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
- asteroids
- asteroid
- Asteroids
- Asteroid
- Metallic, rocky objects without atmospheres that orbit the Sun, but are too small to be called planets.
- ASTID
- Astrobiology Science and Technology Instrument Development and Mission Concept Studies
Astrobiology Science and Technology Instrument Development and Mission Concept Studies
- ATFP
- Astrophysics Theory and Fundamental Physics program
- ATI
- Advanced Technology Initiative
- atmospheric
- atmosphere
- Atmospheric
- Atmosphere
- 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.
- auroral zone
- Auroral zone
- The portion of the Earth that traverses the midnight portion of an oval is known as the auroral zone.
- AVGR
- Ames Vertical Gun Range