posed use of electric propulsion from LEO to GEO, NASA will need to collaborate with and capitalize on the expertise of commercial firms working on electric propulsion and other in-space transportation options.
Recommendation: The SSP program should begin discussions between its management and that of the NASA Space Launch Initiative, so that future milestones and roadmaps for both programs can reinforce one another effectively. This discussion should include specific information on SSP space transportation needs, including cost goals, timelines for deployment, optimal payload mass, packaging requirements, launch rates, and reliability requirements.
Recommendation: The SSP program should encourage expansion of the current in-space transportation program within NASA and interact with its technical planning to ensure that SSP needs and desired schedules are considered.
Recommendation: The SSP program should increase coordination of industry, academic, and other NASA and non-NASA government investments in advanced in-space transportation concepts, particularly in the areas of electric, solar-electric, magnetohydrodynamic, ion, and solar-thermal propulsion.
The components necessary for the ground PMAD subsystem are similar to those used for terrestrial photovoltaic systems. Substantial research and development work is currently supported by the National Center for Photovoltaics, as well as several commercial entities that provide PMAD components for terrestrial photovoltaic applications. In the case of the solar power generation components (i.e., photovoltaics), programs are currently under way in the Air Force to develop high-efficiency, high-specific-power solar cells. The work of the DOE’s National Renewable Energy Laboratory in thin-film solar cells will also be important to the program.
Recommendation: NASA should expand its current cooperation with other solar power generation research and technology efforts by developing closer working relationships with the U.S. Air Force photovoltaics program, the National Center for Photovoltaics, industry, and the U.S. government’s Space Technology Alliance.
Although it may be beyond the means of any one country to fund the research, development, and implementation of SSP, these tasks could be more achievable with international cooperation, which would allow NASA to profit from the work of experts worldwide as well as to contribute its own expertise.
Recommendation: NASA should develop and implement appropriate mechanisms for cooperating internationally with the research, development, test, and demonstration of SSP technologies, components, and systems.
Many technologies for SSP (and other space missions) are not currently on the critical path for any near-term NASA mission. Hence, little funding is available that can be leveraged by SSP to develop these technologies. Without this leverage, it is unlikely that the SSP program can be the sole funding source for such technologies. Examples of such technologies are free-flying robotic servicers, specific space structures, reusable in-space transportation, and certain improvements in thermal materials and management and in power management and distribution. While it is beyond the purview of this study to specifically recommend funding increases for programs other than the SSP program assessed in this report, the committee believes that such technologies are important to the ultimate success of SSP.
The committee has examined the SERT program’s technical investment strategy and finds that while the technical and economic challenges of providing space solar power for commercially competitive terrestrial electric power will require breakthrough advances in a number of technologies, the SERT program has provided a credible plan for making progress toward this goal. The committee makes a number of suggestions to improve the plan, which encompass three main themes: (1) improving technical management processes, (2) sharpening the technology development focus, and (3) capitalizing on other work. Even if the ultimate goal—to supply cost-competitive terrestrial electric power—is not attained, the technology investments proposed will have many collateral benefits for nearer-term, less-cost-sensitive space applications and for nonspace use of technology advances.