FIGURE 3.4 Sample risk mitigation strategy. SOURCE: Slater Voorhees, Lockheed Martin Corporation, “Reusable Booster System (RBS),” presentation to the committee, March 28, 2012. Approved for Public Release.

conditions above Mach 3 and subsequent return to the launch site, it was not clear what else the Pathfinder demonstration would achieve. Also, there was no description or discussion of the Pathfinder MPS design. For example, is it intended to use one ORSC engine, such as the existing NK-33? Or, would it just use an existing, off-the-shelf, available open-cycle engine such as Fastrac17 or a Falcon 1 Merlin? There was no discussion of which, if any, propulsion elements and associated information would be directly applicable to the RBS design.

The committee believes that developing a better definition of the goals and objectives of the Pathfinder program is important for two reasons. First, it is important to understand whether the cost is worth the investment. As stated above, there are important technical questions that can be answered in a Pathfinder program, but these questions will be answered only if the program is properly structured. Second, an understanding is needed of how the results of the Pathfinder program can be used to decide whether it is worthwhile to proceed to the next step, the RBD. So, decision gate criteria should be developed to enable a decision on what to do next after a successful Pathfinder demonstration.

The development of RBS capabilities will challenge many of the limits of state-of-the-art capabilities in such disciplines as propulsion, aerothermodynamics, controls, structures, health monitoring and sensing. The Air Force plans to develop the technologies needed to achieve the goals for the RBS program in phases. An example of a program that follows this approach is provided in Figure 3.4, taken from Lockheed Martin’s presentation18 to the committee. In the figure, the technology development is shown to occur under the following programs: the


17 Fastrac was a LO2/RP-1 60,000 lbf gas-generator cycle engine that delivers a vacuum Isp of approximately 280 s. It was developed by NASA Marshall Space Flight Center (MSFC) and intended for flight application on the X-34 program by Orbital Sciences, but the program was cancelled and the engine inventory was placed in storage at MSFC.

18 S. Voorhees, Lockheed Martin, “Reusable Booster System (RBS),” presentation to the Committee for the Reusable Booster System: Review and Assessment, February 28, 2012. Approved for Public Release.

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