Perspective: The MOSA Approach in Defense Acquisition

By Glen Logan, Lt. Col., USAF | February 1, 2004
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In November 1994, the u.s. undersecretary of Defense for acquisition and technology charted the Open Systems Joint Task Force (OSJTF) to accelerate the acceptance and understanding of open systems for weapon systems electronics acquisitions. The overarching objectives of the Department of Defense’s (DoD’s) open systems initiative are to reduce life cycle costs, deliver combat capability faster, and enhance interoperability.

In the intervening nine years, DoD’s relative emphasis on these objectives has changed somewhat, with much attention being paid to resolving interoperability issues in deployed and emerging systems. With the advent of net-centric operations and warfare (NCOW) concepts in DoD, however, the open systems initiative has an even greater role to play in system-of-systems architectures. The rapidly emerging operational and technical requirements to design and construct net-centric weapon systems will mandate that development costs and schedules be dramatically reduced. A modular open systems approach (MOSA) is the foundation upon which to achieve that end.

Numerous definitions of open systems have been put forth by advocates and cynics, alike. Many of these definitions are controversial–some putting open systems as the end rather than the means. To some, the notion of a system’s being totally non-proprietary is unrealistic and could stifle much needed innovation, which was certainly not the intent.

To circumvent this problem, the OSJTF has chosen to define a modular open systems approach rather than focus on the system per se. According to the OSJTF’s MOSA Program Managers Guide, MOSA is an integrated business and technical strategy that employs a modular design and, where appropriate, defines key interfaces using widely supported, consensus-based standards that are published and maintained by a recognized industry standards organization.

Modular designs feature the following:

  • Partitioning into discrete scalable, reusable modules, consisting of "isolated," self-contained functional elements,

  • Rigorous use of disciplined modular interface definitions, to include object-oriented descriptions of module functionality, and

  • Ease of module replacement and, to the largest extent possible, use of common industry standards for key interfaces.

MOSA interface standards specify the physical, functional and operational relationships between the various elements (hardware and software), to permit interchangeability, interconnection, compatibility and/or communication, and improve logistics support. The selection of the appropriate standards should be based on sound market research and the application of a disciplined systems engineering process.

The preferred implementation of key interfaces between modules uses open standards. These interfaces are selected for ease of hardware and software replacement, based on a detailed understanding of the maintenance concepts, affordability concerns, interoperability needs, and the future evolution of technologies or requirements. The use of open standards produces the largest life-cycle cost benefits.

The latest DoD Directive 5000.1, dated May 12, 2003, requires that A modular, open systems approach shall be employed, where feasible. MOSA is seen as an effective means for implementing the evolutionary acquisition and spiral development strategies that are considered essential to the timely acquisition of weapons systems within the constraints of limited resources. This directive is general and can be satisfied in a number of ways. It does not impose specific constraints on the system design but does imply that systems be developed that possess characteristics generally associated with modularity and openness. A delicate balancing act is required to avoid overly proscriptive design mandates, yet to identify what is truly needed to meet DoD’s targeted cost, schedule and interoperability objectives.

OSJTF also is developing other tools:

  • The MOSA Technical and Business Indicators–a set of measures or attributes indicating the presence of requisite modular open systems characteristics in the system design;

  • The MOSA Program Assessment and Rating Tool adapted from the Office of Management and Budget in conducting program assessments to illustrate compliance with the open systems policy at milestone reviews; and

  • The MOSA Process Model–a Web-based tool for government policy makers, program managers, industry business planners, open system architects, and suppliers of components for military systems.

The application of open systems to weapon systems acquisition is a major cultural change. There are many successes to report, yet much work remains to be done.

Lt. Col. Glen Logan is the deputy, air integration, with the Open Systems Joint Task Force.

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