the nuclear astrophysics facility, and $60 million to $180 million total for multiple experiments in subsurface engineering and geoscience and bioscience. The estimated incremental costs associated with efforts to detect supernovas and proton decay are not significant. Budgetary considerations and further development of the experiments will, of course, change the actual costs of these experiments.
Because both the DUSEL program and the designs for the experiments to address the critical physics questions are still evolving, the committee chose to focus its assessment on the scientific merits of the questions to be addressed rather than on the technical merits of the experiments as they are now designed. Accordingly, it did not assess the technical merits of each experiment being sited at DUSEL or the suitability of alternative sites. Similarly, the committee chose to focus its assessment on the general scientific merits of research in the fields other than physics that would be enabled by the availability of an underground research facility rather than on the specific scientific or technical merits of a particular suite of nonphysics underground experiments. In choosing to focus in this way, the committee intends its assessments to be of value to the future direction of underground research, independent of whether the DUSEL program, as presently conceived, is realized. Finally, the committee assessed the intellectual merit of the underground science of the proposed DUSEL program in the general context of frontier scientific research worldwide. It was not a purpose of this study to rank the different fields or subfields of science, or to prioritize across programs. Neither the individual science questions nor the overall scientific program were compared with those of any other particular projects or investments.
Astronomers are sure that what can be detected by telescopes represents only a small portion of the Universe; furthermore, only a small fraction (~4 percent) is made of normal matter of the type that we live with here on Earth and observe directly elsewhere. The remainder of the Universe is composed of dark matter (about 22 percent), which has mass but does not emit or absorb light, and dark energy (about 74 percent). While dark energy is best studied using astrophysical techniques, direct detection of dark matter in the laboratory is possible, and direct experimental detection of dark matter interactions would profoundly change our understanding of both the microscopic world of elementary particles and the macroscopic astrophysical world, thus bridging the very smallest and the very largest objects in the known Universe.