Dark energy and extra-solar planet studies received strong endorsement today in a once-a-decade astronomy and astrophysics prioritization report. The National Research Council recommended that the highest priority large-scale projects for the next decade should be the $1.6-billion Wide-Field Infrared Survey Telescope (WFIRST) and the $465-million Large Synoptic Survey Telescope (LSST).
The report, titled “New Worlds, New Horizons in Astronomy and Astrophysics,” provides recommendations to US funding agencies on the most important astronomy and astrophysics program that are currently being proposed while accounting for their risks, readiness, and costs. Two years in the making, it considered input from a large proportion of the US astronomy community.
Tony Tyson, LSST director, said, “The community, both scientific and the American public, has come together around this notion of surveying the universe in a complete way”.
LSST, the top-ranked large ground-based project, would be an 8.4-meter telescope in Chile with a 3-gigapixel camera, able to scan the entire southern sky once every three nights. It would investigate the distributions of visible and dark matter and supernovae throughout the universe and use that to infer details of the structure of the universe through time.
The results would allow scientists to test various theories of dark energy and how it is driving the expansion of the universe. In addition it could watch for near-earth objects such as asteroids that could pose a risk to Earth in the future.
The top-ranked large space project is the newly named WFIRST, a 1.5-meter telescope that would orbit a point in space called the second Lagrange point, 1.5 million km from Earth. It would investigate dark energy, the poorly understood effect that is causing the universe to expand at an accelerating rate.
The project is based on the previous Joint Dark Energy Mission “Omega” proposal but is expanded to include searches for extra-solar planets. WFIRST would find them by looking for the small deviations in brightness as planetary systems pass in front of distant stars.
The dark-energy community had been split over which of a few competing proposals should go forward, while rising costs and tangles over the relative roles of NASA and the Department of Energy looked like they might doom the project. In October, Jon Morse, director of NASA’s astrophysics division said NASA would wait until it saw the recommendations of this report to assess their position on a dark-energy mission. A proposed 2013 start on WFIRST could enable launch in 2020.
A similar European project called Euclid is competing with other astronomy proposals for a 2017 or 2018 launch slot in the European Space Agency’s Cosmic Vision program and the report suggests that collaboration with Europe should be considered.
Astronomers see LSST and WFIRST as complementary approaches to understanding dark energy, although if budgets remain tight, each camp makes arguments for its own superiority in different ways.
Steve Kahn, deputy project director for LSST, said some astronomers have questioned whether a space mission is absolutely necessary to solve the dark energy problem but, “It’s what the problem requires. The principle benefit of space is to look into the infrared, which is blocked by the atmosphere. We can combine those results with the LSST visible light observations to reduce the systematic errors which are really limiting our measurements”.
The NRC committee emphasized the complementary nature of space and ground missions and also made recommendations about medium- and small-sized projects. The exoplanets theme arose in all sizes of mission. Wired
