Every 10 years, the U.S. astronomy community goes through the collective exercise of ranking its dream projects, hoping that a few of them will see the light of day with the blessing of the U.S. Congress and funding agencies. The latest such "decadal survey ," has been released this morning and two megascopes have emerged as the top choices for the next decade. On land, the winner is the $463 million Large Synoptic Survey Telescope (LSST), a wide-field optical telescope that will help investigate dark energy, supernovae, and other areas. In space, the community's top choice is the $1.6 billion Wide-Field Infrared Survey Telescope—until now known as the Joint Dark Energy Mission—which will enable researchers to study dark energy, find Earth-like planets, and survey multiple galaxies, including our own. Both are in the planning and design phase, having already received funds on the order of a few million dollars from public and private sources.
The new decadal survey, released today by the National Research Council, is the sixth in a series of such reports that have been written since the 1960s. Although these reports have always been influential—policymakers like scientists to rank their needs—only two of the seven major projects that appeared on the wish list in the 2001 survey have been funded, leading astronomers to wonder if the exercise is as useful as they'd like it to be.
Previous surveys have also been faulted for providing unrealistic cost estimates, as low as a fifth of what certain missions have ended up costing. As a result, there has been considerable pressure on the committee that authored today's report to prioritize projects more effectively and estimate costs better.
The committee has attempted to address those concerns by hiring a contractor to do the cost estimations. Also, unlike previous surveys, the latest one gives each project a high, medium, or low rating in terms of "technical risk."
LSST was on the 2001 wish list as well. Preliminary work on designing the telescope and readying its site in Chile has been ongoing. Receiving another endorsement from the community in this decadal survey will likely give it the boost it needs to get further funding from the government and private organizations.
The committee's decision to pick the Wide-Field Infrared Survey Explorer is not all that surprising either. The mission has been in the planning stages for a few years now, and both NASA and the Department of Energy (DOE) have already provided some funds for fleshing out the proposal. The project is also likely to attract Europe as a contributor; both NASA and DOE have been discussing a possible partnership with the European Space Agency.
The report also endorses a number of other large-scale space projects: In second place among the space options is a proposed augmentation to the Explorer program, which supports small- and medium-sized missions with specific science goals. In third place, the Laser Interferometer Space Antenna, which would help detect long gravitational waves. Fourth on this list is the International X-ray Observatory.
In the category of large-scale, ground-based projects, right behind LSST is a recommendation to fund a Mid-Scale Innovations Program within the National Science Foundation to fund projects that cost more than $4 million and less than $135 million. In third place is the Giant Segmented Mirror Telescope, which like LSST was on the 2001 list as well. And fourth on the list is an international ground-based high energy gamma-ray telescope array.