The Mission Assurance Guide: System Validation and Verification to Achieve Mission Success
Sergio Guarro
Aerospace has codified a set of core processes and supporting disciplines to ensure successful development, deployment, and operation of space systems ranging in type and complexity.
In the context of a major engineering endeavor such as the acquisition of a space system, mission assurance is that part of the systems engineering and integration activities which, by means of a combination of design validation and product verification, provides both the designer and the user with a high degree of confidence in the successful execution of the required system functions.
Consistent with this perspective, mission assurance is at the core of the Aerospace charter and represents one of the primary technical functions that the corporation performs for its national security space customers. Accordingly, Aerospace has prioritized a series of development initiatives to better document and facilitate the application of mission assurance processes. One of these initiatives led to the recent publication of the Mission Assurance Guide.
The Aerospace Mission Assurance Guide, published in 2007. |
Principles and Organization
The Mission Assurance Guide addresses mission assurance from a systems engineering perspective. It introduces the fundamental principles and objectives, then further defines them in practical terms as a hierarchically organized set of standard processes and methodologies. These processes cover the complete life cycle of space, launch, and ground system programs, from concept to disposal, and are systematically interweaved in their application to achieve a repeatable and successful mission outcome.
Mission assurance objectives complement key acquisition tasks. For example, in the early conceptual phases of a program, the primary objective is to ensure that the architecture and system requirements are aligned with user needs and expectations. A parallel and equally important goal is to lay the contractual groundwork for staffing, generation of design-relevant data, and open communications necessary for successful program execution. As the program moves from design through fabrication to checkout and operation, the mission assurance focus moves accordingly to ensure that the integrity of the system design is maintained throughout.
An essential complement of the guide is the database of mission assurance tasks that it references. These tasks—grouped according to execution timelines, hierarchy, and functional organization—are selected and tracked using a software tool associated with the database. This combination of database and software is known as the Mission Assurance Verification Matrix, and it constitutes the actual implementational instrument of the Mission Assurance Guide. In addition to facilitating task management and tailoring, this matrix enables a number of other user functions—most notably, the various types of assessments defined in the guide to gauge the quality of planning and execution of mission assurance activities by individual programs.
Processes and Disciplines
The guide defines mission assurance in terms of a reference set of core mission assurance processes, supporting mission assurance disciplines, and associated tasks. This definition draws from a foundation of systems engineering principles and from Aerospace experience in applying engineering best practices to the procurement and launch-readiness certification of space systems. This experience has established that a judiciously combined application of the mission assurance processes and disciplines maximizes the likelihood that a system will not only meet its basic, specified performance requirements, but also user expectations regarding safety, operability, suitability, and supportability.
Core Mission Assurance Processes
Core mission assurance processes identify and organize—in a standard systems engineering execution flow that naturally lends itself to actual programmatic implementation—tasks that focus on the validation and verification of system acquisition activities. Because these activities are sequentially linked in "waterfall" fashion, the bulk of the tasks associated with each core process are typically concentrated in one or two specific acquisition phases, although the entire process may span several phases of the acquisition life cycle (see sidebar, Core Mission Assurance Processes).
Timeline distribution of core mission assurance processes with respect to program acquisition phases identified in NSS-03-01. The bulk of the tasks associated with each core process are typically concentrated in one or two specific acquisition phases, although the entire process may span several phases of the acquisition life cycle. |
The core processes can actually be executed through a combination of tasks and technical approaches that can vary in nature and depth. A degree of flexibility is in fact necessary to accommodate the scope and constraints of each specific space program implementation. Such flexibility is achieved through a tailoring process, which is an essential element in defining the program mission assurance plan. In the course of this process tailoring, the core processes also draw upon the mission assurance supporting disciplines, borrowing specific subsets of tasks as necessary to construct an efficient and effective mission assurance program.
The six core mission assurance processes defined by the guide are: requirements analysis and validation; design assurance; manufacturing assurance; integration, testing, and evaluation; operational readiness assurance; and mission assurance reviews and audits. The tasks contained within each of these processes are designed to cover, from a validation and verification standpoint, the typical systems engineering activities employed during the life cycle of a typical space system, from inception to operation.
Supporting Mission Assurance Disciplines
Supporting mission assurance disciplines provide the more technically oriented underpinning of mission assurance application and include engineering methodologies and techniques that specifically address system design validation and product verification (see sidebar, Supporting Mission Assurance Disciplines).
The support disciplines provide execution instructions that are broadly accepted in the technical community, including recommended or mandated tools, techniques, models, and standards. Each individual discipline involves a comprehensive and coordinated flow of execution tasks that typically span the entire life cycle of a space program. Any single program, however, usually selects a reduced subset of the entire body of tasks within a discipline. This selection is a key part of the program-specific tailoring conducted at program onset, which takes into account, on the one hand, program risk priorities, and on the other, practical budget and resource constraints.
 Insertion of support discipline task sets into core process execution flow. Each individual discipline involves a comprehensive set of execution tasks that typically span the entire life cycle of a space program. A given program, however, will generally select a reduced subset of these tasks. |
The seven supporting mission assurance disciplines addressed by the guide are: risk assessment and management; reliability engineering; configuration management; parts, materials and processes engineering; quality assurance; systems safety assurance; and software assurance. Tasks and practices that are part of these disciplines are selectively chosen during tailoring to support the execution of certain portions of core mission assurance processes. Tasks and practices from traditional engineering disciplines—e.g., structural mechanics, fluid dynamics, etc.—also may complement the core processes. The aggregation of discipline elements into the core processes may be planned to occur, from a task execution point of view, in any of the program life cycle phases, as required by the overall program mission assurance plan.
The Mission Assurance Plan
The core processes, supporting technical disciplines, and associated tasks defined by the guide provide the framework needed to formulate a program-specific mission assurance plan to validate and verify the concept development, design, manufacturing, integration, test, deployment, and operations of a space system. This reference framework covers all the system development and utilization activities defined in the acquisition directives of both the Department of Defense (NSS-03-01) and the National Reconnaissance Office ("Directive 7"). It must be tailored to suit the needs of each specific program, and this tailoring process requires a series of distinct steps.
Step 1: Core Process Tailoring by Acquisition Phase
The full set of executable core mission assurance process tasks must be tailored to reflect the objectives, risks, and constraints of each individual space program. The tailoring produces a phase-dependent organization of tasks, which also reflects the acquisition phase that the program is entering (i.e., concept study, concept development, preliminary design, complete design, fabrication and integration, fielding and checkout, and disposal). This tailoring essentially involves the identification of core process tasks to be executed and the selection of support discipline tasks to augment and complement them. Normally, the tailoring will also tie individual mission assurance tasks, or groups of tasks, to existing elements of the program "work breakdown structure" (WBS—essentially, the list of everything needed to bring a system to its full operational capability).
Step 2: Mission Assurance Plan Risk Assessment
The extent and scope of the mission assurance plan is practically defined once a comprehensive set of executable tasks has been selected for each of the core mission assurance processes. The guide provides an instrument to evaluate the overall adequacy of the plan in the form of a "plan risk assessment." This is based on the risk rating of each task associated with a WBS element, deduced from the task's relative importance and intended depth of execution (i.e., the amount of time and personnel assigned to it), and on a risk roll-up algorithm that proceeds upwards in the hierarchical task and WBS structures, producing risk ratings for groups of tasks and/or entire WBS areas. The significance of the risk rating is that it permits a rapid engineering evaluation of the adequacy of resources assigned to validation and verification in all significant program areas. It also enables, in relative terms, a judgment of the overall balance of the associated mission assurance plan. If inadequacies are identified in either sense, then the process-tailoring step can be revisited to achieve a better risk rating and balance.
 The risk roll-up view in the Mission Assurance Verification Matrix for a specific WBS area of a space program. The risk roll-up produces risk ratings for groups of tasks or entire WBS areas. |
Step 3: Mission Assurance Task Reference Documentation
After the mission assurance plan has been defined in terms of core processes and tasks, then the task instructions, planned timelines, and reference documentation can be also defined. The associated activities are supported by the Mission Assurance Verification Matrix, which also records the relative information in its task database, including active links to supporting technical instructions, specifications, and standards.
Step 4: Mission Assurance Task Execution Tracking
Progress in implementing the mission assurance plan is measured in terms of two parameters associated with the execution of each task—namely, the variance of task execution timelines (e.g., actual versus planned start and completion dates) and the degree to which the task closure criteria have been met. The number and type of criteria—e.g., successful completion of tests, independent analyses, reviews, etc.—is task-dependent and is documented in the Mission Assurance Verification Matrix.
Step 5: Mission Assurance Task Execution Assessment
The information recorded in the Mission Assurance Verification Matrix concerning task closure criteria and their satisfaction in actual execution enables an assessment of residual risk. As in Step 2, the residual risk rating for each task can be propagated upward through the task hierarchy to produce residual risk ratings for entire program areas. The residual risk information can be used as part of the overall program readiness and launch certification process to help determine whether the level of risk in any particular area is acceptable, or whether additional assurance activities are warranted. The residual risk assessment following plan execution completes the sequence of mission assurance activities recommended by the guide and directly supported by the Mission Assurance Verification Matrix.
 Risk-rating information synthesis for a Mission Assurance Verification Matrix task or group of tasks. The risk rating permits a rapid engineering evaluation of the adequacy of resources assigned to validation and verification in all significant program areas. It also helps in judging the overall balance of the associated mission assurance plan. |
Conclusion
The implementation of mission assurance cannot succeed without a solid foundation of baseline activities executed by space program contractors and suppliers. Beyond that, however, mission assurance requires detailed technical insight into each program by a truly independent organization to measure the effectiveness and outcome of core processes and tasks. Through the disciplined application of mission assurance practices, Aerospace has contributed to the current string of successful launches and their associated missions on orbit.
As practiced by Aerospace, mission assurance comprises a set of management and engineering activities organized into two complementary classes—core processes and supporting disciplines—for which the Mission Assurance Guide provides a formal definition and codification. In essence, the guide provides the means for making mission assurance practices more accessible and repeatable across all the space programs that the company supports.
Besides the definition of reference processes and disciplines, successful programmatic implementation of mission assurance relies on the application of risk criteria to tailor processes and tasks onto a specific program based on resource and schedule constraints and system priorities. Thus, the breadth and depth of mission assurance processes for a given program will depend on several factors, including budget, schedule, technology maturity, purpose, and mission criticality.
As programs transition to their operational phase or achieve legacy status, attention shifts to those programs that are still in the formative and production stages; but mission assurance continues for the life of the program. Technologies advance, acquisition policies change, the industrial base reorganizes—and this creates a challenge for critical program management; but it also underscores the importance of comprehensive and consistent mission assurance support.
Acknowledgments
The author thanks Rich Haas for his support in developing the Mission Assurance Guide as well as those who contributed chapters: George Cuevas, Ron Duphily, Jim Gebhard, James Gin, Dan Hanifen, Paul Hesse, Leslie Holloway, Andrew Hsu, Rick Maynard, Art McClellan, Steve Robertson, Gary Shultz, Mark Simpson, Dana Speece, Joe Statsinger, Lou Tolentino, Bill Tosney, Linda Vandergriff, Julie White, and Howard Wishner.
