NASA astrophysics setbacks prompt debate on future of decadal surveys

Following recent setbacks for two flagship missions, NASA’s lead science official is proposing that the astronomy and astrophysics community delay work on its upcoming decadal survey. Thomas Zurbuchen, associate administrator of the NASA Science Mission Directorate, is also advocating a shift toward smaller, less expensive missions to avoid a similar situation in the future. But some of the scientists who are set to begin this year on the 2020 survey are expressing reservations about postponing what they consider to be an important snapshot of the state of their field. [Update, 25 May: Zurbuchen announced via Twitter that the decadal survey will remain on schedule.]

The debate over the future of decadal surveys for space science took place on 2 May during a meeting of the National Academies’ Space Studies Board. The board serves NASA by channeling the expertise of the scientific community into decadal surveys and other studies that guide formulation and implementation of NASA’s science mission portfolio. Attendees pondered the lessons the community should learn from the delay in the launch of the James Webb Space Telescope (JWST), which was given highest priority in the 2001 astrophysics decadal survey , and the reduction in scope of the Wide-Field Infrared Survey Telescope (WFIRST), the top recommendation of the 2010 decadal .

Zurbuchen acknowledged that the decadal survey belongs to the community, so he stressed that he will follow what the board, which is led by Caltech astrophysicist Fiona Harrison, decides in the coming months. But he cautioned that “a decadal that has no vision, no real forward-leaning character, is not going to stick with you for a decade.”

The meeting came at a complicated time for the astronomy and astrophysics community. In March an independent review found that JWST would not meet its 2018 target launch date; the successor to the Hubble Space Telescope is now expected to launch no earlier than May 2020. The mission has grown in cost considerably from a 2009 baseline of $4.4 billion, and it has been delayed multiple times since an original expected launch in 2014. Most recently, the mission has faced technical issues related to spacecraft integration. A separate independent review board will issue a report by early June assessing what is necessary to ensure JWST‘s success in the final stages of its development and launch, including whether it will breach an $8 billion development cost cap set by Congress.

WFIRST, which is designed to advance understanding of dark energy and exoplanets, has also faced multiple obstacles recently. Last fall an independent cost review found that the mission was likely to exceed its $3.2 billion target life-cycle cost by about $400 million. In response, Zurbuchen ordered that mission leaders scale back the telescope to keep costs in line with the original target. Then, in its fiscal year 2019 budget request, the Trump administration advocated canceling WFIRST in view of “higher priorities.” So far Congress has not supported that suggestion. The FY 2018 appropriations law provided continued funding for WFIRST and reaffirmed its commitment to abiding by decadal survey recommendations.

As for FY 2019, the House appropriations committee in a 16 May report proposed to fund WFIRST at $150 million, level with FY 2018 but half of what NASA says it needs to keep the mission on track. Legislators did endorse the White House’s recommendation of about $305 million for JWST, $229 million less than the mission received in 2018.

Debating a delay

Zurbuchen noted that assuming WFIRST proceeds, JWST and WFIRST are set to dominate the NASA astrophysics division queue for most of the next decade. That led him to repeat his call for delaying the 2020 decadal survey, which he first floated after the March announcement that JWST‘s launch would be pushed back to 2020. “It’s really hard to do a visionary and a great decadal while half of the decade is basically allocated for, so we have very little free energy for the rest of the decade,” he said.

Zurbuchen also urged the board to break from the tradition of structuring the astronomy and astrophysics decadal survey around a single, large strategic mission like JWST or WFIRST—what he called a “build the next one big thing” approach . That would push NASA in a new direction, as the agency is already studying four mission concepts for a future large space telescope—Lynx , Origins Space Telescope , Habitable Exoplanet Imaging Mission , and Large UV/Optical/IR Surveyor —to guide the survey committee’s evaluations. More broadly, Zurbuchen made a plea to the board to think innovatively. “Whenever you sit on a panel in which you have tremendous financial constraints, it is very easy to get into a realm where you are intellectually conservative as well,” he said.

Several board members resisted Zurbuchen’s proposal. Princeton astrophysicist Adam Burrows took the strongest stand against a delay, saying there is a “great deal of enthusiasm for getting on with the job and getting the decadal survey out.” Harrison, the board chair, said that among her colleagues “there is a strong sense there has been a tremendous amount of change in science” since the last decadal survey, including the discovery of gravitational waves. She said that many in the community are ready for a survey that will revisit the state of the field and take another look at the direction of its science.

UCLA astrophysicist Ned Wright suggested that the survey committee would benefit from a more realistic appreciation of NASA’s budgetary and schedule constraints. He recounted that the last astrophysics decadal survey erred when it proposed WFIRST without fully understanding that JWST‘s budget would crowd it out. “What went wrong is we didn’t have a good handle on how much JWST was going to cost,” he said.

Another approach?

Attendees highlighted the recently completed decadal survey on Earth observations from space as an alternative model for structuring a decadal survey. The cochairs of that survey’s committee, former NASA chief scientist Waleed Abdalati and Global Weather Corporation chief technology officer Bill Gail, discussed their strategy of identifying seven broad categories of “target observables” rather than setting priorities for scientific research or specific mission concepts.

NASA Earth science division director Michael Freilich called the survey, which guides his division’s efforts, “brilliant” and “thoughtful.” He said the approach gives the division flexibility in determining how to best obtain priority observations and in scaling or adapting the recommendations to future budget outcomes and management strategies. Notably, the Earth science division has moved away from the use of large strategic missions in recent years in favor of larger numbers of less expensive satellites.

This article is adapted from a 10 May post on FYI, which reports on federal science policy with a focus on the physical sciences. Both FYI and Physics Today are published by the American Institute of Physics.