DISSERTATION COST OPTIMIZATION IN REQUIREMENTS MANAGEMENT FOR SPACE SYSTEMS Submitted by Tami E. Katz Department of Systems Engineering In partial fulfillment of the requirements For the Degree of Doctor of Philosophy Colorado State University Fort Collins, Colorado Spring 2021 Doctoral Committee: Advisor: Steve Simske Ron Sega Erika Miller John Macdonald Copyright by Tami E. Katz 2021 All Rights Reserved ABSTRACT COST OPTIMIZATION IN REQUIREMENTS MANAGEMENT FOR SPACE SYSTEMS When producing complex space systems, the transformation of customer needs into a realized system includes the development of product requirements. The ability to generate and manage the requirements can either enable the overall system development or drive significant cost and schedule impacts. Assessing practices in the industry and publications, it is observed that there is a substantial amount of documented approaches to address requirement development and product verification, but only a limited amount of documented approaches for requirements management. A complex system can have tens of thousands of requirements across multiple levels of development which, if not well managed, can lead to hidden costs associated with missed requirements and product rework. With current space system projects being developed at a rapid pace using more cost constrained approaches such as fixed budgets, an investigation into more efficient processes, such as requirements management, can yield methods to enable successful, cost effective system development. To address the optimal approach of managing requirements for complex space systems, this dissertation assesses current practices for requirements management, evaluates various contributing factors towards optimization of project costs associated with this activity, and proposes an optimized requirements management process to utilize during the development of space systems. Four key areas of process control are identified for requirements management optimization on a project, including utilization of a data focused requirements management approach, development (and review) of requirements using a collaborative software application, ensuring the requirement set is a consolidated with an appropriate amount of requirements for the project, and evaluating when to officially levy requirements on the product developers based on requirement maturation stability. Multiple case studies are presented to evaluate if the proposed requirements management process yields improvement over traditional approaches, including a simulation of the current state and proposed ii requirements management approaches. Ultimately, usage of the proposed optimized set of processes is demonstrated to be a cost effective approach when compared against traditional processes that may adversely impact the development of new space systems. iii ACKNOWLEDGEMENTS Research and generation of new material is not a solo activity, and significant appreciation goes to those that helped me produce this dissertation. The support from those that gave of their time and shared their experiences working on projects has been invaluable, and greatly added to the depth of this research. Thank you to Lou Wheatcraft, Katie Trase, Ken Eastman, Raymond Wolfgang, Joel Knapp, Kevin Orr, David Hill, Angie Wise and John Curry. Those that passionately seek to improve the field of requirements in a voluntary capacity have also contributed to this project; thank you to the INCOSE Requirements Working Group co-chairs, Lou, Kevin, Mike Ryan and Rick Zinni for helping me explore better ways to address requirements on a project. Additional appreciation goes to Saulius Pavalkis at Dassault Systèmes for his support during the development of the requirements management model and simulation, his advice and troubleshooting recommendations helped to keep the modeling progress on course. I would like to acknowledge the companies that I have worked for during this effort, Sierra Nevada Corporation and Ball Aerospace, both of which supported my research and enabled me to continue my education while I was employed full time. The support and advice of my colleague, Erik Wilkinson, has significantly enabled my ability to question established methods to seek more optimal ways. I will always be grateful for his support and inspiration to try new things. Significant support was provided by Dr. Steve Simske, my advisor and guide for pursuing this research, thank you for challenging me to push my ideas further. And finally, my love and appreciation to my husband, Mike Katz, and children Janelle and Jason Katz, for supporting my long nights and weekends researching requirements engineering and writing this paper, thank you for your incredible encouragement! iv TABLE OF CONTENTS ABSTRACT .................................................................................................................................................. ii ACKNOWLEDGEMENTS ......................................................................................................................... iv LIST OF TABLES ........................................................................................................................................ x LIST OF FIGURES .................................................................................................................................... xii Chapter 1: INTRODUCTION ................................................................................................................ 1 1.1 The Challenge with Requirements ................................................................................................ 1 1.2 Dissertation Organization ............................................................................................................. 3 Chapter 2: CONCEPT OF REQUIREMENTS ENGINEERING .......................................................... 5 2.1 The Systems Engineering Process and the Project Life Cycle...................................................... 5 2.2 Overview of Requirements Engineering ....................................................................................... 8 2.2.1 Terminology and Authoritative Publications ........................................................................ 8 2.2.2 The Requirements Development Processes ........................................................................ 12 2.2.3 Requirements Development Among Different Organizations ............................................ 20 2.2.4 Concept of Requirements Traceability................................................................................ 22 2.2.5 Results of Poor Requirements Engineering ........................................................................ 26 2.3 Requirements Engineering Conclusions ..................................................................................... 29 Chapter 3: INVESTIGATION INTO REQUIREMENTS MANAGEMENT ...................................... 30 3.1 Current Approaches to Requirements Management ................................................................... 30 3.1.1 Definition of Requirements Management ........................................................................... 30 3.1.2 Requirements Management Process Models ...................................................................... 31 3.1.3 Why Requirements Change on a Project ............................................................................ 46 3.1.4 Requirement Stability Using TBX Management ................................................................ 50 3.1.5 Requirements Management for Product Lines .................................................................... 53 3.1.6 Ensuring Requirements Quality through Requirements Management ................................ 54 3.1.7 Data Attributes for Requirements Management ................................................................. 56 3.1.8 Conclusion on Current Approaches to Requirements Management ................................... 56 3.2 Newer Requirements Management Trends ................................................................................. 57 3.2.1 Trends Based on the INCOSE Requirements Working Group Efforts ............................... 57 3.2.2 Trends Based on Author Published Research Efforts ......................................................... 60 3.2.3 Trends in Various Industries ............................................................................................... 61 v 3.2.4 Requirements Management (RM) Tools ............................................................................. 64 3.2.5 Observations from Requirements Engineering Practitioners .............................................. 80 3.2.6 Requirement Trends Conclusions ....................................................................................... 94 Chapter 4: CHALLENGES ASSOCIATED WITH SPACE SYSTEMS ............................................. 96 4.1 Overview of the Space Industry .................................................................................................. 96 4.1.1 Complexity in Space Systems ............................................................................................. 96 4.1.2 Definition of a Successful Space System Project ............................................................. 103 4.1.3 Space System Cost Calculations as a Function of System Requirements ......................... 105 4.2 Space Project Example 1: MAVEN ........................................................................................