The Space Studies Board does not have the expertise to improve or contest these assessments of the robustness of the present budget approach. The Board is obviously in favor of a strong science program, however it fits into the agency's overall agenda. It is not certain that if one of NASA's major thrusts were excised, the savings would remain to nourish the survivors. Our working assumption has to be that money for new things will have to come out of today's level of funding, or less. Money is needed for new technology, new instruments, new spacecraft, new launches, and operations.
Launch costs are unavoidable, imposed by physics and our present launch technology.
And there's a limit to how much can be shaved from piloted flight before safety is impacted. This is a question that is now being asked. It supports the theoretical basis for science in space, and pays for innovations in instrumentation and data interpretation. In short, it's used for formulating the questions to ask in space, and for advancing our fundamental competence for getting answers in space. Asking a question and making a measurement are the two halves of the scientific method.