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

296 Newell, Homer E.
Newell, Homer E. (1915–1983)
An internationally recognized authority in atmospheric
and space science. Newell earned his Ph.D. in mathematics
at the University of Wisconsin in 1940 and served as
a theoretical physicist and mathematician at the Naval
Research Laboratory from 1944 to 1958. During part of
that period, he was science program coordinator for
Project Vanguard and acting superintendent of the atmosphere
and astrophysics division. In 1958, he transferred
to NASA to assume responsibility for planning
and developing the new agency’s space science program.
He soon became deputy director of spaceflight programs.
In 1961, he assumed directorship of the office of space
sciences, and in 1963, he became associate administrator
for space science and applications. Over the course of his
career, he became an internationally known authority in
the field of atmospheric and space sciences, as well as the
author of numerous scientific articles and seven books,
including Beyond the Atmosphere: Early Years of Space Science.
217 He retired from NASA in late 1973.
Newton, Isaac (1643–1727)
A great English scientist who organized our understanding
of physical motion into three scientific laws, now
known as Newton’s laws of motion. Among other
things, these laws explain the principle of rockets and
how they are able to work in the vacuum of outer space.
Newton’s law of universal gravitation forms the basis of
celestial mechanics and our understanding of the movement
of satellites, both natural and artificial. See Newton’s
orbital cannon.
Newton’s law of universal gravitation
Two bodies attract each other with equal and opposite
forces; the magnitude of this force, F, is proportional to
the product of the two masses, m 1 and m 2, and is also proportional
to the inverse square of the distance, r 2 between
the centers of mass of the two bodies. This leads to the
equation:
F =
Gm 1m 2
� r 2
where G is the gravitational constant.
Newton’s theory of gravity was superseded by Einstein’s
general theory of relativity.
Newton’s laws of motion
Three laws that form the foundation of classical mechanics
and describe how things move. The laws, which introduce
the concepts of force and mass, are: (1) A body continues
in its state of constant velocity (which may be zero) unless
it is acted upon by an external force; (2) For an unbalanced
force F acting on a body, the acceleration a produced is
proportional to the force impressed, the constant of proportionality
being the inertial mass m of the body; that is,
F = ma; and (3) In a system where no external forces are
present, every action force is always opposed by an equal
and opposite reaction. Newton’s laws (2) and (3) in Mach’s
formulation reduce to: “When two small bodies act on
each other, they accelerate in opposite directions and the
ratio of their accelerations is always the same.”
Newton’s orbital cannon
Isaac Newton discussed the use of a cannon to place an
object in orbit in his Principia Mathematica (1687)—the
book that defined classical physics and provided the theoretical
basis for space travel and rocketry. Newton used
the following thought experiment to explain the principle
of Earth orbits. Imagine a mountain so high that its
peak is above Earth’s atmosphere; on top of this mountain
is a cannon that fires horizontally. As more and
more charge is used with each shot, the speed of the cannonball
will be greater, and the projectile will fall to the
ground farther and farther from the mountain. Finally, at
a certain speed, the cannonball will not hit the ground at
all but will fall toward the circular Earth just as fast as
Earth curves away from it. In the absence of drag from
the atmosphere, it will continue forever in Earth orbit.
NGSS (Next Generation Sky Survey)
A supercooled infrared space telescope designed to survey
the entire sky with a sensitivity more than 1,000
times greater than that of previous missions. NGSS
would result in the discovery of millions of new cosmic
sources of infrared radiation, including many circumstellar
disks, some of which are in the process of forming
planetary systems. NGSS, which would be led by Edward
L. Wright of the University of California, Los Angeles, is
among four mission proposals chosen by NASA as candidates
for two MIDEX (Medium-class Explorer) flights
to be launched in 2007 and 2008.
NGST (Next Generation Space Telescope)
A large space telescope, to be known as the James Webb
Space Telescope after NASA’s second Administrator, that
is scheduled for launch in 2010 and will be the successor
to the Hubble Space Telescope (HST). It will have a primary
mirror 6 m in diameter (2.5 times as large as HST’s)
and will operate at wavelengths between those at the red
end of the visible spectrum and those at the middle of
the infrared range. Located at the second Lagrangian
point, 1.5 million km from Earth, so that it can point
permanently away from the infrared glow of the Sun and
Earth, it will not be serviceable by the Space Shuttle.