WASHINGTON — Despite problems with another large astronomy mission and its own threatened cancellation, NASA’s Wide Field Infrared Survey Telescope (WFIRST) is expected to clear a major review next month after having reduced its costs.

At a meeting of the Committee on Astronomy and Astrophysics of the National Academies’ Space Studies Board here March 27, NASA officials said WFIRST was on track to complete a review called Key Decision Point (KDP) B April 11, allowing it to enter Phase B of its development.

That came after an effort to reduce the mission’s cost to $3.2 billion triggered by an independent review in October. That review concluded WFIRST’s cost had grown to $3.9 billion, with potential additional increases of up to $300 million to meet a “Class A” risk classification used by large missions rather than the less-stringent Class B that WFIRST was operating under.

That cost-cutting is complete. “We did, in fact, come up with a baseline that fits at $3.2 billion, and retains in excess of 30 percent reserves in the lifecycle cost,” said Jeffrey Kruk, WFIRST project scientist, in a presentation at the meeting. That cost estimate is at the 50 percent confidence level, he said, the requirement for the KDP-B review.

The majority of the cost cuts, he said, don’t affect the mission’s science. Some were what he called “painless” accounting shifts, such as taking into account international contributions as well as work by NASA’s space technology directorate on the spacecraft’s coronagraph instrument. Others came through the normal process of refining the spacecraft’s design as it matures, including eliminating one processing system on the spacecraft and simplifying planned integration and testing. Kruk estimated those changes accounted for two thirds to three fourths of the savings.

Other cuts did affect the mission’s science, he acknowledged. The mission relaxed the performance requirements for detectors used by its primary wide-field instrument, although a decrease in operating temperature enabled by another design change will help reduce noise.

The biggest change, he said, is turning the other WFIRST instrument, a coronagraph, into solely a technology demonstration. “The direction to us was that we were being too ambitious” by adding science requirements to the instrument that informed its design, he said. “That had impacts in a lot of areas.”

Major aspects of WFIRST, though, remain unchanged. The spacecraft continues to use a 2.4-meter telescope donated to NASA by another government agency, believed to be the National Reconnaissance Office. The spacecraft will retain its ability to be serviced to extend its lifetime and will also still be compatible with any future starshade mission to aid in the study of exoplanets. Kruk said that the starshade compatibility requires little hardware and minimal overall cost to the mission.

With those cuts in place, the mission completed a system requirements review and mission definition review in late February, he said, clearing the way for the KDP-B review as part of an overall schedule that leads to a launch in September 2025.

However, the administration’s fiscal year 2019 budget proposal seeks to cancel the mission. That decision, agency officials previously said, did not reflect on WFIRST’s cost problems but rather a decision to allocate the money that would have been spent on WFIRST on other agency priorities, including exploration programs.

For now, that proposal has no effect on WFIRST’s development. “We’ve been directed to simply proceed with our project plan exactly as before,” Kruk said. An omnibus spending bill for fiscal year 2018, signed into law March 23, provided $150 million for WFIRST, nearly $25 million above the administration’s original request.

In the report accompanying the 2018 bill, appropriators hinted at their opposition to the 2019 proposal to cancel WFIRST. “The agreement reiterates the importance of the decadal survey process and rejects the cancellation of scientific priorities recommended by the National Academy of Sciences decadal survey process,” it stated. WFIRST was the top-ranked flagship-class mission in the 2010 decadal survey report for astrophysics.

However, even if Congress rejects the cancellation of WFIRST, delays in the development of the James Webb Space Telescope, announced by NASA March 27 while the committee was discussing WFIRST, could affect the mission’s development. The delay in JWST’s launch to May 2020, and an expected breach of its $8 billion cost cap, could lead Congress to shift funds from WFIRST or other astrophysics programs.

Kruk said there has been, so far, little discussion about any impact JWST delays will have on WFIRST because the magnitude of those delays remains uncertain. He warned, though, that any WFIRST delay that results from dealing with JWST issues will affect its cost as well.

“If there’s a delay in our development, there’s no way that is not going to equate to an increase in the lifecycle cost,” he said.