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Unformatted text preview: is occurs depends on many factors. For
a flight system with a short mission duration, such as a
Spacelab payload, disposal may require little more than
de-integration of the hardware and its return to its
owner. On large flight projects of long duration, disposal
may proceed according to long-established plans, or
may begin as a result of unplanned events, such as
accidents. Alternatively, technological advances may
make it uneconomic to continue operating the system
either in its current configuration or an improved one.
In addition to uncertainty as to when this part of
the phase begins, the activities associated with safely
decommissioning and disposing of a system may be
long and complex. Consequently, the costs and risks
associated with different designs should be considered
during the project's earlier phases.
3.7 Role of Systems Engineering in the Project
Life Cycle This
descriptions of the systems engineering activities within
the project life cycle. The first is the Forsberg and Mooz
"vee" chart, which is taught at the NASA
program/project management course. me second is the NASA program/project life cycle process flow developed
by the NASA-wide Systems Engineering Process
Improvement Task team, in 1993/94.
3.7.1 The "Vee" Chart Forsberg and Mooz describe what they call "the
technical aspect of the project cycle" by a vee-shaped
chart, starting with user needs on the upper left and
ending with a user-validated system on the upper right.
Figure 7 provides a summary level overview of those
activities. On the left side of the vee, decomposition and
definition activities resolve the system architecture,
creating the details of the design. Integration and
verification flow up and to the right as successively
higher levels of subsystems are verified, culminating at
the system level. This summary chart follows the basic
outline of the vee chart developed by NASA as part of
the Software Management and Assurance Program.
("CIs'' in the f...
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