The prioritization process included projects not yet started from the preceding decadal survey, Astronomy and Astrophysics in the New Millennium (AANM).2 The rationale for their review stems from a need to ensure that these research activities are still up to date technologically, that the science questions they tackle remain compelling and a high priority, and that their cost and schedule are still commensurate with the science return. Given the multidecade timescales required for development of major facilities from concept to construction to operation, it should not be surprising that many of these projects have evolved in technical and/or scientific scope since AANM, further motivating their reconsideration.
Because of the need for significant technical expertise in developing a prioritized program from a wide array of candidate ongoing and proposed activities, four Program Prioritization Panels (PPPs) were also established by the NRC to assist the committee in studying technical and programmatic issues within the following areas:
Electromagnetic Observations from Space (EOS)—activities funded largely by NASA, some with a DOE component;
Optical and Infrared Astronomy from the Ground (OIR)—activities funded largely by NSF and private entities, some with a DOE component;
Particle Astrophysics and Gravitation (PAG)—activities funded by NASA, NSF, and DOE; and
Radio, Millimeter, and Submillimeter Astronomy from the Ground (RMS)—activities funded largely by NSF with some private components.
The charge to the PPPs and their principal recommendations for new activities are summarized in Appendix B. The PPPs started with the SFPs’ conclusions on the highest-priority science and then developed a program to address this science optimally. The panels also referred to pertinent NRC reports, as well as reports from the astronomy community. The individual PPP reports contain these and other non-facility recommendations spanning a range of scales.3 Each panel was charged to consider only the potential program within its designated subdiscipline. By design this approach results in a combined program that is too large to be implemented in any reasonable budget scenario. It thus fell to the survey committee to synthesize the panel recommendations with additional consideration for the issues discussed in Chapters 3, 4, 5, and 6, and thereby develop a merged implementable program for the entire astronomy and astrophysics enterprise.