advanced technology development needed for future launch systems. The committee makes the following six recommendations.

Recommendation 1: Launch responsiveness should be a major attribute of any reusable launch system. To address this perceived disconnect, the Air Force should establish specific responsiveness objectives independent of the Evolved Expendable Launch Vehicle launch-on-schedule requirements that can be used to drive technology development.

The committee believes that responsiveness considerations should be a major consideration when addressing reusable launch systems and their supporting technologies. At the present time, responsiveness requirements beyond a launch-on-schedule philosophy have not been defined. Since these responsiveness requirements can drive vehicle and technology needs, it is important for the Air Force to define nominal responsiveness goals to provide focus for research and development activities.

Recommendation 2: Independent of any decision to proceed with RBS development, the Air Force should proceed with technology development in the following key areas: reusable oxygen-rich staged-combustion hydrocarbon-fueled engines; rocketback return-to-launch-site operations; vehicle health management systems; and adaptive guidance and control systems. These technologies will have to be matured before they can support any future decision on RBS, and most of them will be also applicable to alternative launch system concepts.

Continued development is needed in these four principal areas to sufficiently mature these technologies to the point where significant investments can be committed to the RBS programs. The committee recommends that investments in these four areas continue independent of a decision to proceed with RBS development at this time. Since these technologies have application beyond RBS, with the exception of rocketback RTLS, this technology maturation will benefit the Air Force independent of RBS in areas of advanced rocket propulsion, system reliability, and vehicle autonomy.

Recommendation 3: The Air Force Research Laboratory’s (AFRL’s) Pathfinder project is under way to demonstrate in flight, using a small-scale vehicle, the critical aspects of the return-to-launch-site maneuver. To increase chances for Pathfinder’s success, AFRL should develop and fly more than one Pathfinder test vehicle design. In addition, competition among RBS concepts should be maintained as long as possible to obtain the best system for the next generation of space launch.

The use of a rocketback maneuver for RTLS operations of an RBS has not been previously demonstrated, so this approach to reusability carries significant risk. Given these risks and the resulting parameter space for innovative solutions, the Pathfinder program should be executed in a manner wherein several vehicle designs are developed and flown. While this approach will increase costs in the near-term, the long-term benefits to achieving a true high-performance solution will overwhelm this initial cost, if reusability is pursued in the future.

Recommendation 4: The decision to proceed with the RBS development program should be based on the successful completion of the Pathfinder activities and on assurance that the technical risks associated with the reusable oxygen-rich, staged-combustion hydrocarbon-fueled engines, rocketback return-to-launch-site vehicle health management systems, and adaptive guidance and control systems are adequately mitigated.

Given the immaturity of principal technologies and the inherent risks of the rocketback RTLS operation, the committee recommends that the decision to proceed with RBS development be tied to the successful completion of the Pathfinder program and suitable mitigation of the principal technical risks. The committee understands that this approach delays potential achievement of an RBS capability. Delaying the decision to proceed with the RBS



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