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

174 guidance, midcourse
guidance, midcourse
Guidance of a spacecraft while it is en route to its destination.
guidance system
One of the systems in a space vehicle designed to put the
vehicle on a desired trajectory prior to thrust cutoff, or a
system in a vehicle that establishes the desired path from
launch to target.
guided missile
An unmanned weapon that is controlled by some system
from its launch until it hits its target.
guided missiles, postwar development
In the decade after World War II, the U.S. government,
persuaded by the conservative arm of the military,
decided that the nation’s main deterrent force should
consist of manned intercontinental bombers supplemented
by air-breathing guided missiles evolved from
the German V-1 (see “V” weapons). Despite the early
postwar warnings of Gen. Henry H. Arnold and others,
who argued for the immediate development of longrange
ballistic missiles capable of carrying atomic warheads,
this approach was deemed too costly and difficult
guided missiles, postwar development The first instrumented
Hermes A-1 test rocket fired from White Sands Proving
Ground. Hermes, based externally on the V-2, contributed
to the development of the Redstone missile. NASA
at the time. Just after the war, former NACA (National
Advisory Committee for Aeronautics) chairman Vannevar
Bush, then director of the Office of Scientific
Research and Development, expressed the prevailing
mood in a testimony before a Congressional committee:
“There has been a great deal said about a 3,000-mile highangle
rocket. In my opinion, such a thing is impossible
today and will be impossible for many years.”
Thus, in the late 1940s and early 1950s, the United
States focused on developing relatively small guided missiles
for air-to-air, air-to-surface, and surface-to-air interception
and as tactical surface-to-surface weapons. The
Soviets, by contrast, threw themselves into building huge
ballistic missiles capable of carrying the heavy nuclear
weapons of that period over thousands of miles—a decision
that gave them a long-lasting lead in space exploration.
Interservice rivalry led the Army, the Navy, and the Air
Force to pursue essentially separate missile-development
programs. The great success of the Air Corps during the
war had conditioned it to think in terms of winged vehicles.
As a result, the Air Force put more effort at first into
two subsonic missile programs, Snark and Matador, than
the supersonic, long-ranged Atlas. Later came the Navaho;
but by this time it was clear that such weapons were not
effective compared to longer-range ballistic missiles.
While the Air Force concentrated on relatively small
guided missiles, the Army, having inherited a stockpile of
V-2s and a team of German rocket specialists, naturally
chose to build on this ready-made pool of hardware and
expertise. But as the supply of Nazi missiles diminished
and it was evident that rocket technology had moved
beyond the V-2 stage, the Army initiated the Hermes
program and, later, the development of the Redstone
missile based on the liquid-propellant engine of the
Navaho.
By the early 1950s, intelligence revealed that the Soviets
were evolving long-range nuclear ballistic missiles that
posed a serious threat to the West. In response, the priority
in the United States switched from the development
of guided missiles to intermediate-range and intercontinental
ballistic missile programs, including the Jupiter,
Atlas, and Thor.
Gulfstream
To train Space Shuttle pilots in landing the vehicle prior
to making their first spaceflight, NASA uses a modified
Gulfstream 2 executive jet. The cockpit has been divided
into two—with Shuttle controls on the left and normal
Gulfstream controls on the right. The flight dynamics of
the Shuttle were calculated before the Shuttle actually
flew, and the Gulfstream 2 trainer was modified accordingly.
The calculations proved to be so accurate that very