The Complete Book of Spaceflight: From Apollo 1 to Zero Gravity

Nimbus
A series of seven NASA weather satellites, launched between
August 1964 and October 1978 into polar orbits,
that photographed cloud cover and monitored air pollution.
Nimbus helped develop the technology that would
be used in later meteorological programs.
Nimiq
Canada’s first direct broadcast satellite, launched by
Telesat on May 20, 1999; “nimiq” is Inuit for “something
that unifies.” It has 32 Ku-band (see frequency bands)
transponders and has been designed primarily to serve
the Canadian market, with the capability of offering full
North American coverage in the future.
NIMS (Navy Ionsopheric Monitoring System)
See Transit.
nitric acid (HNO 3)
A commonly used oxidizer in liquid-propellant rocket
engines between 1940 and 1965. It most often took the
form of RFNA (red fuming nitric acid), containing 5% to
20% dissolved nitrogen dioxide. Compared to concentrated
nitric acid (also known as white fuming nitric
acid), RFNA is more energetic and more stable to store,
but it produces poisonous red-brown fumes. Because
nitric acid is normally highly corrosive, it can be stored
and piped by only a few materials, such as stainless steel.
However, the addition of a small concentration of fluoride
ions inhibits the corrosive action and gives a form
known as IRFNA (inhibited red fuming nitric acid).
nitrogen tetroxide (N 2O 4)
A yellow-brown liquid that is among the most common
storable oxidizers used by liquid-propellant rocket
engines today. For example, it is used with MMH (see
hydrazine) in the Space Shuttle orbital maneuvering system.
Although it can be stored indefinitely in sealed containers,
its liquid temperature range is narrow and it is
easily frozen or vaporized.
NNSS (Navy Navigational Satellite System)
See Transit.
NOAA (National Oceanic and Atmospheric
Administration)
A U.S. government body that manages and operates
environmental and meteorological satellites and provides
data to users worldwide. Having absorbed ESSA
(the Environmental Science Services Agency) in 1970, it
took over responsibility for the TIROS program. All successful
launches in this program now carry the NOAA
designation.
NOSS (Naval Ocean Surveillance Satellite) 297
non-coherent
A communications mode wherein a spacecraft generates
its downlink frequency independent of any uplink frequency.
Noordung, Herman (1892–1929)
The pseudonym of Herman Potocnik, a relatively
obscure officer in the Austrian Imperial Army who became
an engineer and, encouraged by Hermann Oberth,
published in 1928 a seminal book, Das Problem der
Befahrung des Weltraums (The Problem of Space Travel:
The Rocket Motor), 220, 221 which focuses largely on the
engineering aspects of space stations. In it, Noordung
deals with issues such as weightlessness, space communications,
maintaining a habitable environment for the
crew, and extravehicular activity. Noordung’s proposed
design consists of a doughnut-shaped structure for living
quarters, a power-generating station attached to one end
of the central hub, and an astronomical observation station.
He was among the first to suggest a wheel-shaped
design for a space station to produce artificial gravity; he
also argued the scientific value of such a station in a synchronous
orbit above Earth.
North American Aviation
A U.S. aircraft and aerospace company, founded in 1928,
that played a central role in the early American space program.
It was responsible for the development of the X-15
rocket plane and, through its Rocketdyne Division, the
propulsion system for the Redstone rocket, the Apollo
Command and Service Modules, the second stage of the
Saturn V, and the F-1 and J-2 rocket engines. Earlier, North
American Aviation had provided some of the best-known
combat planes of World War II and the postwar years,
including the F-51 Mustang, the B-25 Mitchell bomber,
and the F-86 Sabre. In 1966, North American Aviation
merged with Rockwell Standard to form North American
Rockwell, which, in 1976, was renamed Rockwell International.
In 1996, Rockwell became part of Boeing.
nosecone
The cone-shaped leading end of a rocket vehicle, consisting
of a chamber in which a satellite, instruments, organisms,
or auxiliary equipment may be carried, or of an
outer surface built to withstand high temperatures generated
by aerodynamic heating.
NOSS (Naval Ocean Surveillance Satellite)
U.S. Navy ocean surveillance satellites. NOSS detected
the location of naval vessels using radio interferometry,
and consisted of a main spacecraft and several subsatellites
linked by fine wires several hundred meters apart.