US astronomy community sets plan to fit tight times

The flagship projects in astronomy and astrophysics for the coming decade will likely be the Wide-Field Infrared Survey Telescope (WFIRST) and the Large Synoptic Survey Telescope (LSST). They ranked first in the big-ticket space-based and ground-based categories, respectively, in New Worlds, New Horizons in Astronomy and Astrophysics (known as Astro2010), the decadal survey released by the National Research Council in August. The survey sets priorities for the field for fiscal years 2012 through 2021 and will serve as a handbook for funding agencies.

“The survey puts science first. We were emphatic about that,” says Astro2010 committee chair Roger Blandford of Stanford University. The committee narrowed its focus to three broad science objectives: searching for the first stars, galaxies, and black holes; seeking nearby, habitable planets; and understanding the fundamental physics of the universe. Those goals—plus fitting into a tight budget—inform the mix of space- and ground-based facilities and related activities the committee recommended.

Big surveys and midsize missions

The top space priority in the $1 billion and up category is WFIRST, a survey “designed to settle essential questions in both exoplanet and dark energy research,” according to Astro2010. In an unusual move, the committee came up with WFIRST by merging three projects that have similar hardware requirements: In addition to missions devoted to identifying planets and to studying dark energy, WFIRST folds in the capability to survey the sky at near-IR wavelengths.

The second top-dollar space priority is to increase funding for NASA’s Explorers Program, a flexible catchall for multiple midscale missions. The committee chose the program because of its ability to respond quickly to scientific advances and its demonstrated high scientific return per dollar. Third on the list is LISA, the Laser Interferometer Space Antenna, a set of three spacecraft that will form a triangle in space, with separations of about 5 million km; the antennas will measure gravitational waves from such sources as white-dwarf binaries, compact orbiting stars, and merging black holes. The fourth and final pick is IXO, the International X-ray Observatory , which Astro2010 says “will transform our understanding of hot gas associated with stars and galaxies in all evolutionary stages.” The Astro2010 committee wants WFIRST and the Explorers Program augmentation done this decade. For LISA and IXO, the committee recommends funding at a level that will see the projects realized in the next decade.

In the medium-cost space category (roughly $100 million-$1 billion), the committee picked two technology development programs—the first to prepare for a future mission to study nearby Earth-like planets and the second to lay the foundation for a cosmic microwave background mission to study the early universe’s epoch of inflation (see table).

On the ground, the top pick in the highest-cost category (greater than $135 million) was the LSST, an 8.4-meter wide-field optical telescope to be built in Chile that will scan the visible sky every couple of nights. Among other things, it will probe dark matter, dark energy, and variable objects and will search for potentially dangerous near-Earth asteroids; the 30 terabytes of data it produces nightly will be freely available. The second large-scale ground priority is for NSF to create a program, modeled on NASA’s Explorers Program, for projects in the $4 million to $135 million range. In third place is the Giant Segmented Mirror Telescope. The survey says that NSF should decide immediately which of two US-led GSMT projects—the Giant Magellan Telescope (GMT) or the Thirty Meter Telescope (TMT)—to join at the 25% funding level. Next on the list is the Atmospheric Cherenkov Telescope Array, an international project to study very high energy gamma rays. The CCAT (formerly the Cerro Chajnantor Atacama Telescope), a 25-meter wide-field sub-millimeter telescope, is the only medium-scale ($4 million-$135 million) project on the ground-based list.

Nearly a dozen lower-cost, unranked priorities are also listed. Examples include creating theory and computation networks, increasing funding for the Gemini Observatory in light of the UK’s withdrawal from the international project, and upping funding for the Telescope System Instrument Program, through which NSF pays for the development of instruments for private facilities in exchange for observing time for the broader US astronomy community.

Additional recommendations include one calling for US investors—public and private—to seek new approaches to realizing US participation in international facilities. The survey recommends international strategic planning meetings for the field every five years. It says the funding agencies should plan for long-term curating of large astronomical data sets. NSF should consider consolidating the operational structures of the Gemini Observatory and the National Optical Astronomy Observatory. And, the survey says, an independent standing committee should be formed to advise the funding agencies on implementing the recommendations.

Cost, schedule, risk

Astronomy and astrophysics have been moving at a “breakneck pace of discovery” since about 1960, says Blandford. “There are new technologies, a lot of interest, and a lot of ingenuity. That’s not slowing down.” The field is still discovery oriented, he says, and making sure it could respond to new ideas “was a factor in thinking about what facilities to recommend.” So was balance—between flagship missions and smaller activities, between tiny and huge collaborations, between technology development and new projects, and among different areas of research. “We were very conscious of the tradeoffs,” Blandford says. Adds Astro2010 committee member Lars Bildsten of the Kavli Institute for Theoretical Physics at the University of California, Santa Barbara, “We don’t want the large projects to eat the lunch of the small investigators.”

More than in any previous decadal survey—this is the sixth—the Astro2010 committee strove to create a fiscally realistic program. An outside contractor, Aerospace Corp, helped assess costs. Risk was judged by evaluating readiness, technical issues, and proposed schedules. “It’s a probabilistic exercise, an uncertain business, but we did the best we could,” says Blandford.

If budgets stay flat, few new activities can be started without killing existing ones. At NASA, science funding won’t flow until the James Webb Space Telescope launch, expected mid decade. For the first time, the Department of Energy joined NASA and NSF in sponsoring the survey—and thus seeking advice in astronomy and astrophysics. DOE’s Office of Science and NSF both anticipate flat budgets, but for its recommendations the committee assumes purchasing power will grow at 4% a year, in line with the current administration’s stated policy of doubling the budgets of those agencies over the course of a decade.

For the first time, unrealized priorities from earlier decadal surveys were reconsidered. In the past, such projects were assumed to stay in the funding queue. “We expressly compared past recommendations with new proposals. The significance is that you have to fit [the priorities] into the budget,” explains Blandford. So, for example, the ground-based GSMT made the cut, but a fairly advanced space interferometry mission did not, and NASA is expected to abandon it.

“There were 10 times more activities that we could have responsibly supported than any budget could have underwritten,” says Blandford. “Plenty of things that were proposed that do not appear were very exciting. In a sense, this was the biggest challenge. From the start we knew we were in a highly cost-constrained environment.”

All told, five science panels, four program prioritization panels, six infrastructure study groups, scores of town meetings, and more than 700 panel and community submissions contributed to the decadal survey over the two-year process. “This was a Herculean effort to plan for everyone for an entire decade in a field that is moving rapidly,” says Rocky Kolb, a theoretical cosmologist at the University of Chicago who did not take part in the survey.

“Sensible and defensible”

Not surprisingly, despite wide endorsement of the survey, everyone can quibble with something in the recommendations. For Shri Kulkarni, director of Caltech’s Optical Observatories, the biggest disappointment is that the exosolar planet program “is inadequate in scope. The report gives lip service, but the allocation of resources is not effective.” He notes that in the past “we went too much for big things, and this is costing us now.”

Other people complain that good words are not enough: The survey should have recommended funding for the Square Kilometre Array, an international radio telescope.

But perhaps the most chatter is about the large optical telescopes. For starters, people from both US-led GSMT projects are quick to note that the LSST outranked them because of technical readiness, not superior science. From what he hears in the hallways, Harvard University’s Christopher Stubbs says, “The people who work in large telescopes are truly stunned.”

Another twist is the survey’s recommendation that NSF “immediately” throw its lot in with one of the GSMTs—a recommendation that is variously welcomed and questioned. The project scientist for the TMT, Jerry Nelson of the University of California, Santa Cruz, says, “We think having this shoot-out is important and should be done immediately. We would like to complete our partnership.” Some of the project’s international partners “will feel more comfortable” if the TMT includes the US government, he adds. “It’s the principle, not the money.” Both GSMT collaborations have significant financial commitments from international and private partners and say that NSF participation will not make or break them. “I don’t think it needs to shake up either telescope,” says Wendy Freedman, who as director of the Carnegie Observatories is spearheading the effort to build the GMT. “I think each will go ahead, and should go ahead.” Others question the need for a hasty decision on NSF’s part, given that it won’t have money for such a project for years.

The biggest disappointment, of course, is that money is tight. Says Freedman, “The committee had to make hard choices, and I think they made sensible and defensible choices. It’s an excellent report and will stand us in good stead.”