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Words begining with "N"

Nadir

Point on Earth directly beneath a satellite, the opposite of zenith. Compare with subsatellite point.

nano

See International System of Units.

Nanometer (nm)

One billionth of a meter. Nanometers are used to measure wavelengths in the electromagnetic spectrum.

NASA

See National Aeronautics and Space Administration.

NASA Centers

The ten major NASA Centers are:

NASA Prediction Bulletins

Reports published by NASAs Goddard Space Flight Center providing the latest orbit information on satellites. The report gives information in three parts:

  1. Two line orbital elements,
  2. Longitude of the south to north equatorial crossings
  3. Longitude and heights of the satellite crossings for other latitudes.

    NASDA

    See Japanese National Space Development Agency.

    National Aeronautics and Space Administration (NASA)

    U.S. Civilian Space Agency created by Congress. Founded in 1958, NASA belongs to the executive branch of the Federal Government.

    NASA's mission to plan, direct, and conduct aeronautical and space activities is implemented by NASA Headquarters in Washington, D.C., and by ten major centers spread throughout the United States. Dozens of smaller facilities, from tracking antennas to Space Shuttle landing strips to telescopes are located around the world. The agency administers and maintains these facilities, builds and operates launch pads, trains astronauts, designs aircraft and spacecraft, and sends satellites into Earth orbit and beyond, and processes, analyzes, and distributes the resulting data and information. See NASA Centers.

    NASA shares responsibility for aviation and space activities with other federal agencies, including the Departments of Commerce, Transportation, and Defense. Much of the work on major projects such as the Space Shuttle and the Space Station is done in the private sector by aerospace companies under government contract.

    From its inception, NASA has been directed to pursue the expansion of human knowledge of phenomena in the atmosphere and space. NASA's programs of basic and applied research extend from microscopic sub-atomic particles to galactic astronomy. In addition to enhancing scientific knowledge, thousands of the technologies developed for aerospace have resulted in commercial applications. Science offices at NASA Headquarters carry out a wide range of research activities to fulfill NASA's science goals. Science offices within NASA are:

    • Office of Mission to Planet Earth (MTPE) focuses on the "home planet" as a dynamic system of land, ocean, atmosphere, and life that can be investigated on a global scale from space using remote-sensing tools.

       

    • Office of Life and Microgravity Sciences and Applications explores the basic physics of how solids, liquids, and gases behave in space; seeks an understanding of the basic mechanisms that underlie space adaptation - developing more effective countermeasures to mitigate the physiological effects of space flight; and studies the role of gravity on life.

       

    • Office of Space Science includes the Space Physics and Astrophysics Division which studies the entire universe of stars and galaxies, including the sun. The Solar System Exploration division has launched spacecraft to all the known planets except Pluto in its quest to study the solar system.

    National Center for Atmospheric Research (NCAR)

    Non-profit organization dedicated to furthering understanding of the Earth's atmosphere. Located in Boulder, Co., NCAR is operated by the University Corporation for Atmospheric Research (UCAR) and sponsored by the National Science Foundation (NSF).

    National Oceanic and Atmospheric Administration (NOAA)

    NOAA was established in 1970 within the U.S. Department of Commerce to ensure the safety of the general public from atmospheric phenomena and to provide the public with an understanding of the Earth's environment and resources. NOAA includes: the National Ocean Service which charts the oceans and waters of the U.S. and manages 265,000 acres of estuarine reserves; the National Marine Fisheries Service which maintains the world's largest and most complex marine fisheries management system; the NOAA Corps which operates 18 NOAA research and survey ships and flies 15 NOAA aircraft; and the Office of Oceanic and Atmospheric Research which supports experiments, laboratories, and the National Sea Grant College Program, among other efforts. NOAA has two main components: the National Weather Service (NWS), and the National Environmental Satellite, Data, and Information Service ( NESDIS)

    The National Weather Service provides weather watch and warning services to the public through 57 Weather Service Forecast Offices (WSFO) and over 100 smaller local Weather Service Offices (WSOs) nationwide. Three national forecasting centers provide general and specialized guidance to WSFOs using computer forecast models, satellite data, and conventional surface and upper air observations from around the world. The centers are:

    • National Meteorological Center, Camp Springs, Maryland

       

    • National Severe Storms Forecast Center, Kansas City, Missouri

       

    • National Hurricane Center, Coral Gables. Florida.

    NWS River Forecast Centers (RFCs) provide river staqe and flood forecasts. NESDIS provides support to the Weather Service forecast mission by operating a series of environmental satellites and disseminating satellite imagery and derived products to the National Centers and WSFOs. NESDIS operates three national data and information centers: the National Geophysical Data Center, the National Climatic Data Center (NCDC, and the National Oceanographic Data Center (NODC). See SOCC. NOAA organizations perform numerous services in addition to monitoring weather conditions They assess crop growth and other agricultural conditions, sense shifting ocean currents, and measure surface temperatures of oceans and land. They relay data from surface instruments that sense tide conditions, Earth tremors, river levels, and precipitation.

    National Space Seience Data Center (NSSDC)

    The NSSDC provides on-line and off-line access to a wide variety of astrophysics, space plasma and solar physics, lunar and planetary, and Earth science data from NASA space flight missions, in addition to selected other data, models, and software. Located at Goddard Space Flight Center (GSFC) in Greenbelt, Maryland, the NSSDC is sponsored by the Information Systems Office of NASA's Office of Space Sciences. NSSDC on-line data and services are currently free of charge, offline support (e.g., replications and mailing of magnetic tapes) are available for the cost of fulfilling the request.

    The NSSDC Master Catalog (NMC) provides an on-line listing of available data sets and the forms that the data are available in (such as CD-ROM), and provides information about the spacecraft and experiments (including past, present, and future NASA and non-NASA) from which these data were obtained. The on-line NASA Master Directory (NMD) identifies and briefly describes data of potential interest to the NASA research community, and where possible, provides electronic links to publicly-accessible data at sites world-wide. On-line information services are made avail- able through the menu-based NSSDC Online Data Information Service (NODIS).

    For more information contact:

    •  
      CRUSO (Coordinated Request & User Support Office)
      National Space Science Data Center
      c/o World Data Center-A-R&S
      (only if corresponding from outside the USA)
      NASA Goddard Space Flight Center, Code 633.4
      Greenbelt, Maryland 20771

       

    • Phone: (301) 286-6695, FAX: (301) 286-1771

       

    • Internet: request@nssdca.gsfc.nasa.gov

       

    • DECnet: nssdca::request

    National Weather Service (NWS)

    See National Oceanic and Atmospheric Administration.

    Nautical Mile

    A unit of distance (U.S.) equal to exactly 1.852 kilometers or about 6076.1 feet. A nautical mile is approximately equal to 1/60 of a degree or 1 minute of arc of a great circle of the Earth (i.e., 1 minute of arc of latitude or of lonqitude at the equator).

    NCAR

    See National Center for Atmospheric Research.

    NCDC

    National Climatic Data Center, located in Asheville, North Carolina. See National Oceanic and Atmospheric Administration.

    Near Infrared

    Electromagnetic radiation with wavelengths from just longer than the visible (about 0.7 micrometers) to about two micrometers. See electromagnetic spectrum.

    Nephanalysis

    A type of analysis using satellite cloud pictures to study the relationship between cloud forms and storm systems. In classical mythology, Nephele was a woman Zeus formed from a cloud.

    Nepheloccygia

    Clouds that resemble recognizable shapes.

    NESDIS

    National Environmental Satellite Data and Information Service. See National Oceanic and Atmospheric Administration.

    Newton's Law of Universal Gravitation

    All bodies attract each other with what is called gravitational attraction. This applies to the largest stars as well as the smallest particles of matter.

    The force of attraction between two small bodies (or between two spherical bodies of any size) is proportional to the product of their masses and inversely proportional to the square of the distance between their centers. In other words, the closer two bodies are to each other, the greater their mutual attraction. As a result, to stay in orbit, a satellite needs more speed in a low than a high orbit.

    Kepler's three laws of planetary motion, which had been derived empirically by Johannes Kepler, were obtained with mathematical rigor as a consequence of Newton's law of universal gravitation in conjunction with his three laws of motion.

    Newton's Laws of Motion

    Newton's three laws of motion are:

    1. Every body continues in a state of uniform motion in a straight line unless acted upon by some external force.
    2. The time rate of change of momentum (mass x velocity) is proportional to the impressed force. In the usual case where the mass does not change, this law can be expressed in the familiar form: force = mass x acceleration or F = ma.
    3. To every force or action, there is always an equal and opposite reaction.

    Kepler's three laws of planetary motion, which had been derived empirically by Johannes Kepler, were obtained with mathematical rigor as a consequence of Newton's law of universal gravitation in conjunction with his three laws of motion. See Keplers three laws of motion.

    NGDC

    National Geophysical Data Center, located in Boulder, Colorado. See National Oceanic and Atmospheric Administration.

    Nibble

    Four bits of data.

    Nimbus Satellite Program

    A NASA program to develop observation systems meeting the research and development requirements of atmospheric and Earth scientists. The Nimbus satellites, first launched in 1964, carried a number of instruments: microwave radiometers, atmospheric sounders, ozone mappers, the Coastal Zone Color Scanner (CZCS), infrared radiometers, etc. Nimbus-7, the last in the series, provided significant global data on sea-ice coverage, atmospheric temperature, atmospheric chemistry (i.e. ozone distribution), the Earth's radiation budget, and sea-surface temperature. See Total Ozon Mapping Spectrometer (TOMS).

    NOAA

    See National Oceanic and Atmospheric Administration. Operational designation for the U.S. polar-orbiting.meteorological satellites. Current NOAA spacecraft are variations of the TRIOS-N/NOAA satellite.

    NODC

    National Oceanographic Data Center, located in Washington, D.C. See National Oceanic and Atmospheric Administration.

    NRA

    NASA Research Announcement.

    NREN

    National Research and Education Network.

    NSF

    National Science Foundation.

    NSFNET

    National Science Foundation NETwork.

    NSSDC

    See National Space Science Data Center


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