recommended priorities reflect an executable balance of scientific promise against cost, risk, and readiness. The international context also played an important role in the committee’s deliberations, and many of the large projects involve international collaboration as well as private donors and foundations.
The priority science objectives chosen by the survey committee for the decade 2012-2021 are searching for the first stars, galaxies, and black holes; seeking nearby habitable planets; and advancing understanding of the fundamental physics of the universe. These three objectives represent a much larger program of unprecedented opportunities now becoming within our capability to explore. The discoveries made will surely lead to new and sometimes surprising insights that will continue to expand our understanding and sense of possibility, revealing new worlds and presenting new horizons, the study of which will bring us closer to understanding the cosmos and our place within it.
This report recommends a program that will set the astronomy and astrophysics community firmly on the path to answering some of the most profound questions about the cosmos. In the plan, new optical and infrared survey telescopes on the ground and in space will employ a variety of novel techniques to investigate the nature of dark energy. These same telescopes will determine the architectures of thousands of planetary systems, observe the explosive demise of stars, and open a new window on the time-variable universe. Spectroscopic and high-spatial-resolution imaging capabilities on new large ground-based telescopes will enable researchers to discern the physical nature of objects discovered at both shorter and longer wavelengths by other facilities in the committee’s recommended program. Innovative moderate-cost programs in space and on the ground will be enhanced so as to enable the community to respond rapidly and flexibly to new scientific discoveries. Construction will begin on a space-based observatory that employs the new window of gravitational radiation to observe the merging of distant black holes and other dense objects and to precisely test theories of gravity in new regimes that we can never hope to study on Earth. The foundations will be laid for studies of the hot universe with a future X-ray telescope that will search for the first massive black holes, and that will follow the cycling of gas within and beyond galaxies. Scientists will conduct new ground-based experiments to study the highest-energy photons emitted by cosmic sources. At the opposite end of the electromagnetic spectrum, radio techniques will become powerful enough to view the epoch when the very first objects began to light up the universe, marking the transition from a protracted dark age to one of self-luminous stars. The microwave background radiation will be scrutinized for the telltale evidence that inflation actually occurred. Perhaps most exciting of all, researchers will identify which nearby stars are orbited by planets on which life could also have developed.
Realizing these and an array of other scientific opportunities is contingent on maintaining and strengthening the foundations of the research enterprise that are