NASA’s Vision for Space Exploration calls for a return of humans to the Moon and eventual human spaceflight to Mars. In September 2005, NASA outlined an initial architecture for implementing the Vision in its Exploration Systems Architecture Study (ESAS). NASA is implementing this architecture under the Constellation program. Among the first major efforts of this program are the developments of new space flight systems—including the Ares I Crew Launch Vehicle and the Orion Crew Exploration Vehicle. Ares I and Orion are currently targeted for operation no later than 2015 (see fig. 1). As illustrated by figure 1 above, the Constellation program, including the Ares I and Orion projects, is approaching the end of the formulation phase of NASA’s acquisition life-cycle for spaceflight programs and projects. The purpose of the formulation phase is to establish a cost-effective program that is demonstrably capable of meeting the agency’s objectives. The formulation phase concludes with the preliminary design review and a non-advocate review which marks the end of the formulation phase and the beginning of the implementation phase. During the implementation phase, the program will execute plans developed during the formulation phase. Our work on best practices over the past decade has shown that success in large-scale development efforts like Constellation depends on establishing an executable business case before committing resources to a new product development effort. In its simplest form, a business case requires a balance between the concept selected to satisfy customer needs and the resources—technologies, design knowledge, funding, time, and management capacity—needed to transform the concept into a product. At the heart of a business case is a knowledge-based approach that requires that managers demonstrate high levels of knowledge as the program proceeds from technology development to system development and, finally, production. Ideally, in such an approach, key technologies are demonstrated before development begins, the design is stabilized before prototypes are built or production begins, and testing is used to validate product maturity at each level. At each decision point, the balance among time, money, and capacity is confirmed. In essence, knowledge supplants risk over time. Having adequate knowledge about requirements and resources is particularly important for a program like Constellation because human spaceflight development projects are inherently complex, difficult, and costly. We have reported on several occasions that within NASA’s acquisition framework, the preliminary design/non-advocate review—the hurdle marking transition from program formulation to program implementation—is the point at which development projects should have a sound business case in hand. NASA’s Systems Engineering Policy states that the preliminary design review demonstrates that the preliminary design meets all system requirements with acceptable risk and within the cost and schedule constraints. NASA realized that the Orion project was not ready to complete the preliminary design review process as planned and delayed its initiation from summer 2008 to summer 2009. Furthermore, although NASA officially closed the Ares I preliminary design review process in September 2008, it deferred resolution of the thrust oscillation issue until the Constellation program preliminary design review in March 2010. The business case is the essential first step in any acquisition program that sets the stage for the remaining stages of a program, namely the business or contracting strategy and actual execution or performance. If the business case is not sound, execution may be subpar. This does not mean that all potential problems can be eliminated and perfection achieved, but rather that sound business cases can help produce better outcomes and better return on investment. If any one element of the business case is weak, problems are more likely in implementation. Thus far in the Constellation program, the failure of NASA to establish a sound business case for both the Ares I and Orion projects early is manifesting itself in schedule delays and cost increases. The Constellation program has not yet developed all of the elements of a sound business case needed to justify entry into implementation. Progress has been made; however, technical and design challenges are still significant and until they are resolved NASA will not be able to reliably estimate the time and money needed to execute the program. In addition, cost issues and a poorly phased funding plan continue to hamper the program. Consequently, NASA is changing the acquisition strategy for the Orion project as the agency attempts to increase confidence in its ability to meet a March 2015 first crewed launch. However, technical design and other challenges facing the program are not likely to be overcome in time to meet the 2015 date, even with changes to scope and requirements. Technical and design challenges within the Constellation are proving difficult, costly, and time intensive to resolve. The Constellation program tracks technical challenges in its Integrated Risk Management Application (IRMA). NASA procedures recommend that programs identify and track risks as part of continuous risk management. As of June 9, 2009, IRMA was tracking 464 risks for Ares I and Orion—207 high risks, 206 medium risks, and 51 low risks. We have reported on some of these areas of technical challenge in the past, including thrust oscillation, thermal protection system, common bulkhead, and J-2X nozzle extension. In addition to these challenges, our recent work has highlighted other technical challenges, including Orion mass control, vibroacoustics, lift-off drift, launch abort system, and meeting safety requirements. While NASA has made progress in resolving each of these technical challenges, significant knowledge gaps remain in each of these areas. Descriptions of these technical challenges follow. Thrust oscillation, which causes shaking during launch and ascent, occurs in some form on every solid rocket engine. Last year, we reported that computer modeling indicated that there was a possibility that the thrust oscillation frequency and magnitude may be outside the limits of the Ares I design and could potentially cause excessive vibration in the Orion capsule. Agency officials stated that thrust oscillation is well understood and they are pursuing multiple solutions. These include incorporating a passive damping system inside the first stage solid rocket booster aft skirt that will act like a shock absorber during launch; adding a composite structure and springs between the first and second stages to isolate the upper stage and crew vehicle from the first stage; and could possibly use the upper stage propellant fuel tanks to offset thrust oscillation in the first stage. Officials said that NASA will be unable to verify the success of solutions until thrust oscillation occurs during an integrated flight. Officials noted that because thrust oscillation is not expected to occur in every flight, it is difficult to forecast when the solutions will be verified. The Orion vehicle requires a large-scale ablative heat shield, at the base of the spacecraft, to survive reentry from earth orbit. These heat shields burn up, or ablate, in a controlled fashion, transporting heat away from the crew module during its descent through the atmosphere. NASA is using an ablative material derived from the substance used in the Apollo program. After some difficulties, NASA was successful in recreating the material. Because it uses a framework with many honeycomb-shaped cells, each of which must be individually filled without voids or imperfections, it may be difficult to repeatedly manufacture to consistent standards. According to program officials, during the Apollo program the cells were filled by hand. The contractor plans to automate the process for the Orion Thermal Protection System, but this capability is still being developed. The common bulkhead separates the hydrogen and oxygen fuel within the Ares I upper stage fuel tank. The initial Ares I design employed a simpler two-tank configuration with lower manufacturing costs but did not meet mass requirements. According to project officials, the common bulkhead represents the critical path in both the development and manufacturing of the upper stage. Lessons learned from the Apollo program indicate that common bulkheads are complex and difficult to manufacture and recommend against their use. According to NASA officials, the difficulty of designing and manufacturing common bulkheads stems from the sheer size of components and the tight tolerances to which they must be manufactured. To accelerate the manufacturing process NASA is exploring using an oven with a vacuum bag instead of an autoclave to bond and cure the metallic and composite materials used in the manufacture of the common bulkhead. If this process proves unsuccessful, the program may encounter schedule delays. We have reported in prior years that although the J-2X engine is based on the J-2 and J-2S engines used on the Saturn V and leverages knowledge from subsequent engine development efforts, the number of planned changes is such that, according to NASA review boards, the effort essentially represents a new engine development. A risk within this development is a requirement for a nozzle extension to meet performance requirements. NASA originally planned to pursue a composite nozzle. However, NASA eliminated the composite nozzle extension from the J-2X design because of cost and other considerations, and went with a unique aluminum alloy design, which, according to agency officials, should reduce costs, but has the potential to decrease engine performance and increase mass. Analysis indicates that the alloy nozzle is more likely to be affected by heat than a composite nozzle. In essence, while the alloy nozzle should withstand the heat environment, the composite nozzle allowed for improved performance margins. According to officials, to mitigate the potential problem, NASA is using a proven aluminum alloy with a honeycomb design, similar structurally to the Space Shuttle external tank, which will reduce weight. Contractor officials stated that they will continue to modify the nozzle design as test results are received and analyzed. Controlling for mass has led to significant design changes to the Orion vehicle. Our previous work has shown that controlling for mass is a key factor in the development of space systems. As the mass of a particular system increases, the power or thrust required to launch that system will also increase. This could result in the need to develop additional power or thrust capability to lift the system, leading to additional costs, or to stripping down the vehicle to accommodate current power or thrust capability. For example, NASA went through the process in 2007 to zero- base the design for the Orion to address mass concerns.