NASA’s Space Launch Initiative is an effort to develop and build a second generation of reusable space transportation vehicles. (See fig. 1 and table 1.) NASA’s current transportation vehicle, the space shuttle, has been in use for 20 years and requires a significant portion of NASA’s resources to operate and maintain. The primary goals for SLI are to reduce the risk of crew loss as well as substantially lower the cost of space transportation so that more funds can be made available for scientific research, technology development, and exploration activities. Currently, NASA spends nearly one-third of its budget on space transportation. SLI is part of a broader program—known as NASA’s Integrated Space Transportation Plan—to address space transportation needs. Under the plan, NASA could operate the space shuttle through 2020 and make software and hardware upgrades to the shuttle in order to extend its use to this point. It envisions the deployment of second-generation cargo vehicles to begin around 2011 and crew vehicles around 2014. As with the shuttle, NASA envisions that the second-generation vehicle will reach orbit in two stages. NASA also anticipates building a third generation of vehicles in 2025 and even a fourth generation in 2040. (See fig. 2.) NASA anticipates that these vehicles would reach orbit in one stage; travel beyond low-earth orbit to far-reaching interstellar missions; and employ revolutionary technologies, such as (1) rocket engines that breath oxygen from the air during the climb to orbit rather than carrying heavy oxidizers onboard, (2) propellantless electromagnetic propulsion, and (3) solar-powered space sails. Building the second-generation vehicle will be a considerably complex and challenging endeavor for NASA—from both a technical and business standpoint. For example, NASA plans to develop and advance new technologies for the new vehicle. These include (1) new airframe technologies that will include robust, low-cost, low-maintenance structure, tanks, and thermal protection systems, using advanced ceramic and metallic composite materials, and (2) new propulsion technologies, including main propulsion systems, orbital maneuvering systems, main engines, and propellant management. If successfully developed, NASA believes that these new technologies could substantially reduce the costs to maintain and operate the vehicle and increase its reliability. NASA also plans to develop the new vehicle through partnerships with private industry, academia, and DOD. It is partnering with the private sector so that it can help create business opportunities in space, and it is partnering with DOD because of military needs for a reusable launch vehicle. Such partnerships will require a high level of coordination and communication, since agreements need to be reached on what the basic capabilities of the new vehicle will be, what designs or architecturesshould be pursued, how development costs will be shared, and what individual partner responsibilities will be. NASA recognizes that there are substantial technical and business risks with SLI, and it is undertaking activities aimed at reducing them. To reduce technical risks, for example, NASA is exploring, developing, and testing technologies to make sure that they can be used on the new vehicle, rather than proceeding with the program with uncertainty about whether technologies will be mature enough when they are needed. To reduce business and costs risks, NASA’s goal is to ensure that there is adequate competition in the development of the architecture and that the architectures that NASA pursues will enable convergences with NASA’s requirements and commercial and military missions, and will not pursue vehicles that cannot meet program goals. To date, NASA has already explored hundreds of concepts and technologies that could be used for future government and commercial launch systems and space transportation operations. The “leap-ahead” technologies studied include crew survival systems, advanced tanks and airframe structures, long-life rocket engines, and thermal protection systems. In March 2002, NASA selected 15 of the most promising candidates to go forward into more detailed development. In November 2002, NASA plans to narrow the field down to 3 candidates and in September 2003 to at least 2 candidates. From fiscal year 2003 through fiscal 2006, two competing system architectures will be developed, ready for a full-scale development decision in fiscal 2006. NASA plans to spend $4.8 billion for the SLI program through fiscal year 2006. This investment is to be used for (1) systems engineering and activities concerning the definition of requirements; (2) efforts to compete designs for the reusable launch vehicle as well as efforts to reduce business and technical risks; (3) activities to develop and demonstrate designs, technologies, and system-level integration issues associated with such NASA-unique transportation elements as a crew transport vehicle and cargo carriers; and (4) activities to develop alternative access to the space station as well as to provide contingency backup or relief for the space shuttle. NASA’s efforts to compete designs for the vehicle and reduce technical and business risks consist of approximately $3 billion of the planned initial investment. At the present time, no prototype vehicle integrating all new SLI technologies is planned before NASA’s fiscal year 2006 decision on whether to proceed to full-scale development. According to a NASA official, NASA plans to define the basic requirements for its second-generation space transportation—that is, what the crew size will be, what the payload capacity will be, and what designs or architectures are worth pursuing—by November 2002. These decisions will have a significant impact on the cost, size, and design of the new vehicle. For example, as the payload capacity increases, so does the thrust requirement for the propulsion system, and in turn, the cost to develop and build the system, as well as the cost to operate the system. However, NASA is facing a considerable challenge in reaching the point to where it can finalize SLI requirements. This is primarily because NASA must first make some difficult broader decisions regarding the future of space transportation and other NASA projects, including (1) whether NASA should skip development of a second-generation vehicle in favor of concentrating on the third generation, (2) what the future of the International Space Station will be, and (3) what DOD’s role in developing the new vehicle will be. Moreover, in making these decisions, NASA will need to reach consensus with a wide range of partners who have priorities and concerns different from NASA’s, and it will need to make trade-offs amid uncertainties as to the availability of advanced technologies. First, NASA must complete its ongoing reassessment of its overall space transportation plan. This evaluation is being done as part of NASA’s development of a budget proposal for fiscal year 2004. The options NASA is considering could have a far-reaching impact on the SLI program. One option, in fact, involves postponing efforts to develop a new generation of vehicles indefinitely until there is a major breakthrough in technology that could vastly improve performance and reduce costs. Other options being examined could drastically change NASA’s timetable and requirements for SLI. For example, NASA is looking at developing a crewed vehicle more quickly than currently planned and launching it atop an expendable rocket until it can field a reusable launch vehicle. NASA is also considering deferring some development efforts so that it can aggressively pursue a goal of building a relaunchable vehicle prototype by 2009. Finalizing its decisions on where to go with the space transportation plan will be difficult for NASA, given the uncertainties about the availability of technologies needed to reduce costs and achieve NASA’s performance and safety objectives. Second, NASA is currently reassessing the future of the International Space Station. One decision it needs to make that could significantly affect the SLI program is whether the station should support a crew of seven astronauts, as originally planned, or three. Because of cost growth, NASA plans to cut back to a crew of three, but its international partners have not agreed yet to this decision and are concerned that the cutback will severely undermine planned scientific research. This decision could significantly affect the design and cost of the second-generation vehicle. For example, with a bigger crew size, the overall vehicle will have to be larger; a larger crew cabin and additional backup systems will be required; and, as a result, the cost to develop the vehicle will increase. NASA is also planning to cut back the number of flights to the station from seven to four per year, which could also have an impact on SLI. But again, NASA’s international partners have concerns about this decision, since it would limit the deliveries of resources needed to carry out research activities. At the same time that NASA is looking at cutting back on space station capabilities, it is planning to extend the life of its space shuttle to 2020 with software and hardware upgrades. If NASA can successfully extend the life of the shuttle, it may well find that a second-generation vehicle, which is not expected to begin transporting crews to the space station until at least 2014, would generally be duplicative in capability and therefore unnecessary. NASA plans to make final decisions on the space station by November/December 2002. Third, while DOD and NASA have explored potential common areas of interest for a new space transportation vehicle, DOD has not yet formally defined its requirements. In fact, it is still uncertain whether SLI will be a joint DOD/NASA program. A study conducted by the Air Force and NASA earlier this year revealed that both NASA and DOD shared similar objectives when it came to technologies needed for the new vehicle as well as cargo lift requirements and launch architecture elements. But there were differences with priorities and certain requirements. The Air Force would like the vehicle to operate in stronger winds, more precipitation, and a wider range of temperatures. It would also like the vehicle to operate from an inland U.S. Air Force base. NASA would like the vehicle to stay in orbit for a longer duration and have more maneuverability because of its mission to service the International Space Station. Additionally, NASA will have a higher weight-delivered-to-orbit requirement for its crew vehicle.