WFIRST was the No. 1 rated large-scale mission in the 2010 decadal survey for astrophysics. Credit: NASA illustration

WASHINGTON — The estimated cost of NASA’s next major astrophysics mission after the James Webb Space Telescope has increased by up to 25 percent, growth that a new report warns could hurt other priorities for NASA astronomy missions in the coming years.

The potential cost increase in the Wide Field Infrared Survey Telescope (WFIRST) mission was noted in a report issued by the National Academies Aug. 15 that reviewed the progress by NASA and other agencies in implementing the most recent astrophysics decadal survey, published in 2010.

WFIRST, which became a formal project in February, had an estimated cost of $2.0 to 2.3 billion, based on an independent cost and technical estimate performed by the Aerospace Corp. in 2015. However, the National Academies report said that between the completion of that assessment and the decision to make WFIRST a formal project, known as Key Decision Point A, the cost of the mission had increased by $550 million.

Part of that increase, according to the report, is linked to the decision to fly WFIRST at the Earth-sun L-2 Lagrange point, about 1.5 million kilometers from the Earth, rather than in geostationary orbit as originally planned. Increased prices for the baseline launch vehicle, a United Launch Alliance Delta 4 Heavy, also contributed to the cost growth by an unknown amount. “Some of it may simply reflect more accurate assessment as the mission design matures,” the report added.

NASA spokeswoman Felicia Chou said Aug. 15 that of that $550 million increase, only $100 million was linked to design changes to the WFIRST spacecraft. The rest, she said, was caused by factors that included a change in the estimated launch vehicle price and a delayed launch date.

A formal cost and schedule estimate for WFIRST, which NASA expects to launch in the mid-2020s, won’t be completed until later in the project’s development. However, the report recommended that NASA carry out an “an independent technical, management, and cost assessment” of the mission before it reaches its next major milestone, Key Decision Point B, scheduled for October 2017.

Chou said NASA supported that recommendation. “It is standard practice at NASA to appoint an independent Standing Review Board to conduct a technical, management and cost review at gateway reviews, including the gateway review before Key Decision Point B,” she said. “NASA always planned to do so, and the recommendation of the committee is welcome.”

The report added that, should cost growth on WFIRST affect NASA’s ability to carry out smaller Explorer-class missions, or participate in European gravitational wave and X-ray astronomy missions, “NASA should descope the mission to restore the scientific priorities and program balance by reducing the mission cost.”

The report also discussed the inclusion of an instrument known as a coronagraph, designed to block light from stars to enable WFIRST to directly observe much dimmer planets orbiting them. The coronagraph was not included as part of WFIRST when the 2010 decadal survey identified WFIRST at its top priority large, or flagship, space mission.

The report supported NASA’s decision to add a coronagraph to WFIRST, noting the science it enabled was in line with the overall themes of the 2010 study. However, the report warned that if the coronagraph’s cost increased “much beyond” the current estimate of $350 million, it would “significantly distort the science priorities” set by the 2010 survey. That earlier report recommended NASA spend $100 to 200 million on technology development to support exoplanet studies, which is being fulfilled by the WFIRST coronagraph.

The new report concluded that, overall, both NASA and the National Science Foundation were doing a good job implementing the priorities of the 2010 decadal survey despite budgets that have fallen short of the optimistic projections of that report.

For example, that report based its plans on a recommended scenario where NSF’s astrophysics budget doubled in real-year dollars over the course of the decade. Instead, the new report noted, that budget has “approximately flat” over the decade, thus not keeping pace with inflation. That has led the NSF to start divesting some older observatories it can no longer afford to operate, and reduce access to other telescopes.

At NASA, the report concluded that flat budgets, coupled with a cost increase for JWST, forced the agency to delay or defer some major programs, like WFIRST. Despite those issues, it stated, NASA “has maintained a balanced portfolio through the first half of the decade and, with the assumption of successful completion of an ambitious Explorer schedule, will do so during the second half of the decade as well.”

Jeff Foust writes about space policy, commercial space, and related topics for SpaceNews. He earned a Ph.D. in planetary sciences from the Massachusetts Institute of Technology and a bachelor’s degree with honors in geophysics and planetary science...