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:
- Every body continues in a state of uniform motion in a straight line
unless acted upon by some external force.
- 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.
- 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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