Interactive Requirements Control System for Spacecraft Mission Operations

Howard J. Bender
bender@nova.umuc.edu
University of Maryland 
                          
Abstract
The Mission Operations and Data Systems Directorate (MO&DSD) at
the NASA Goddard Space Flight Center is responsible for developing
and operating the ground data systems to support many of NASAÕs
scientific missions.  During requirements analysis for these
systems, major problems have been the coordination between various
autonomous groups, delays in the final approval of requirements,
verification that all upper level requirements are satisfied by
lower level developments, and the modularization of requirements
groups to encourage reuse.  To address these problems, the MO&DSD
proposed an interactive requirements collection system to foster
communication between people and between levels in the data
systems.  This project, named the Requirements Generation System
(RGS), was installed for operational use in the Fall of 1993.  The
RGS, based on personal computer client/server architecture,
displays mission requirements to users as a set of hierarchical
functional categories.  Requirements integrity is maintained
through four levels of security, based on privileges associated
with each type of user.  By bringing the requirements development
process online, remote users are included in a more effective and
timely fashion.  By including a flexible requirements change
mechanism, easy visibility of requirements to all interested
users, inspections for requirement redundancy, automatic tracing
through different levels of requirements documents, and notation
fields to avoid misunderstandings, the RGS makes the requirements
development and approval process much easier and quicker to
perform.