Page 211 - Intro to Space Sciences Spacecraft Applications

CHAPTER 9

Spacecraft Design

In the complex world of aerospace vehicle design, it is no longer possi-
ble for a single designer to individually create a vehicle which can opti-
mally and capably perform the many functions that modem expectations
place on such systems. The word “system” is not used lightly here, as
more and more often, modem-day systems are complex assemblages of
many different parts. With this in mind, the engineering definition of a
“system” may be introduced:
A system is a set of elements organized to perfom a set of designated
functions in order to achieve specified results. This definition itself intro-
duces additional terms which, in turn, must also be defined:
An element of a system is an identifiable component of the whole that per-
forms some identifiable function. Each element performs particular designut-
edfinctiuns which represent the defined actions, operations, or use of the ele-
ment. These well-defined actions assist the system in achieving its specified
results which are simply the stated objectives or purpose of the system.
Thus defined, it is easy to see that an element may be a system in its
own right. More than just individual pieces of a particular mechanism,
system elements may also include personnel, facilities, information, and
many other factors that are not necessarily physical parts of the mecha-
nism under design.
In viewing the system as a set of many diverse components, it can eas-
ily be seen that a single designer, though competent in one or even a few
fields, may be lacking in some knowledge that may not allow him or her
to compose the optimum method for achieving the particular objective.
Designs of large-scale, complex modern-day systems is a multidiscipli-
nary task calling on the expertise of many toward the one objective.

THE SYSTEMS APPROACH

In order to coordinate the efforts of those contributing to the task, an
organized method must be followed to ensure success. The systems