5.2.3 Configuration Identification and Management

Careful and complete identification of the subscale development article configurations (Pathfinder and RBD) is extremely important to ensure that subsequent full-scale vehicle designs understand what has been tested. As changes are made to these flight test articles, they must be well documented.

Configuration control must be rigorously maintained on the full-scale RBS elements. This is fairly straightforward for the expendable upper stage and payload fairing, which are discarded during every mission. Changes on these items must be documented as they occur, but there is no need for retrofit. For the reusable boosters, however, configuration control must be carefully managed to make sure improvement changes are incorporated across the fleet. During Y-vehicle operations, many changes will undoubtedly be identified. Some will require immediate incorporation to maintain flight status, while others will await the block change for the first production booster. Once several production boosters have achieved flight status, the two Y-vehicles will be retrofitted to incorporate all the current design changes. If a continuous improvement philosophy is adopted (see Section 5.2.2), changes to production vehicles will continue. To better manage this, a leader-follower approach to booster use may be advantageous. If one booster is used for recurring missions, while the others remain in ready status, the nonimmediate changes can be incorporated into the stored boosters without impacting flight operations.

5.2.4 Cost Management

The RBS program will be large enough that it does not escape considerable cost scrutiny throughout its development and fielding. The standard cost management techniques, including earned value management, should be incorporated from the start, with on-ramps for meeting cost objectives that are as rigorous as the technical on-ramps. Two funding philosophies should be incorporated: the program should be budgeted at 80 percent should-cost confidence, and the program should carry a 25 percent management reserve of cost-to-complete at each stage of the program until transition to a fixed-price procurement for the operational vehicles.

One of the biggest problems with the oversight process, including the Nunn-McCurdy system, is that most space systems find (or put) themselves in a position where the capabilities to be provided are “essential” to national security. Therefore, the remaining question is whether there is an alternative way to achieve the capabilities at lower cost. Once a program has spent billions buying down risk, it is highly unlikely that a lower cost option going forward can be found. The Space-Based Infrared System, the Advanced Extremely High Frequency satellite, the Mobile User Objective System, National Polar-Orbiting Observational Environmental Satellite System (NPOESS), and even EELV today are programs that experienced enormous cost growth yet were/are essential and were continued after Nunn-McCurdy breaches, including being restructured, because there was no better alternative. Eventually, decision makers above the program level decided NPOESS was simply in too much trouble and had to be terminated. SpaceX is offering the possibility of an alternative for EELV, in the future if not in the near term, subject to demonstrating the required launch reliability.

Therefore, one of the most important cost management tools is to ensure that RBS is not allowed to become essential until the risk is sufficiently low and cost confidence is quite high. To achieve this, it will be necessary that the current Air Force launch system(s) or mature alternative vehicles be maintained in production while RBS is in development.


RBS will be an Air Force-managed program, and direct involvement with development contractors, hardware manufacturers, and operations will be required. The following committee observations are based on experience with recent Air Force-managed programs.

The National Academies | 500 Fifth St. N.W. | Washington, D.C. 20001
Copyright © National Academy of Sciences. All rights reserved.
Terms of Use and Privacy Statement