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

packetizing
A telecommunications technique used by modern spacecraft
that has superseded the older method of timedivision
multiplexing. In packetizing, a burst or “packet”
of data is transmitted from one onboard instrument or
sensor, followed by a packet from another device, and so
on, in a nonspecific order. Each burst carries an identification
of the measurement it represents so that the
ground data system can recognize it and handle it
appropriately. The scheme adheres to the International
Standards Organization’s (ISO) Open Systems Interconnection
(OSI) protocol suite, which recommends
how different types of computers can intercommunicate.
Being independent of distance, the ISO OSI holds for
spacecraft light-hours away just as it does for local workstations.
pad abort
Halting the mission of a space vehicle still on the launch
pad because of malfunction, change in plans, or other
problems.
paddlewheel satellite
A satellite with large solar panels that are deployed to
generate electrical energy. The panels resemble giant paddles
alongside the satellite. The world’s first paddlewheel
satellite was Explorer 6, launched on August 7, 1959.
PAET (Planetary Atmospheric Entry Test)
A NASA suborbital experiment to study the feasibility of
making mass spectrometer measurements from highspeed
entry probes as they plunge into dense atmospheres.
Launch
Date: June 20, 1971
Vehicle: Scout B
Site: Wallops Island
Pageos (Passive GEOS)
A 30-m diameter sphere made from 0.0125-mm Mylar
externally coated with vapor-deposited aluminum. It was
inflated in orbit to serve as a giant reflector of sunlight
that could be photographed from the surface. In this way,
over a five-year period, Pageos enabled the determination
P
313
of the precise relative location of continents, islands, and
other land masses. Pageos was the second NASA satellite
(following GEOS 1) in the National Geodetic Satellites
Program. The launch, orbit, separation, inflation, and
operation went according to plan, with more than 40
ground stations taking part in the observation program.
The orbit was generally considered too high for dragdensity
study, although some work was done in this area
by the Smithsonian Astrophysical Observatory.
Launch
Date: June 23, 1966
Vehicle: TA Thor-Agena D
Site: Vandenberg Air Force Base
Orbit: 2,953 × 5,207 km × 84.4°
Mass: 55 kg
Paine, Thomas O. (1921–1992)
NASA’s third administrator, during whose term of office
the first seven Apollo manned missions were flown,
including the first two to the Moon’s surface. Paine graduated
from Brown University in 1942 with an A.B. degree
in engineering, and in 1947, from Stanford University
with a Ph.D. in metallurgy. During World War II, he
served as a submarine officer in the Pacific. Subsequently,
he held a variety of research and research-management
positions before being appointed deputy administrator of
NASA in 1968. Upon the retirement of James Webb,
Paine was named acting administrator and nominated as
administrator of NASA in March 1969, a position from
which he resigned in September 1970, to return to General
Electric. In 1985, the White House chose Paine as
chair of a National Commission on Space to prepare a
report on the future of space exploration. Since leaving
NASA 15 years earlier, Paine had been a tireless
spokesman for an expansive view of what should be done
in space. The Paine Commission took almost a year to
prepare its report, largely because it solicited public input
in hearings throughout the United States. The Commission
report, Pioneering the Space Frontier, published in May
1986, espoused “a pioneering mission for twenty-firstcentury
America—to lead the exploration and development
of the space frontier, advancing science, technology,
and enterprise, and building institutions and systems that
make accessible vast new resources and support human