WASHINGTON — The future of NASA’s SOFIA airborne observatory remains in limbo after the astrophysics decadal survey gave the program, proposed for termination by NASA, a vote of no-confidence.

The astrophysics decadal survey final report, released Nov. 4, included sharp criticism of the Stratospheric Observatory for Infrared Astronomy (SOFIA), a program that was identified as a priority in decadal surveys published in 1990 and 2000. SOFIA, which started operations in 2014 after lengthy delays, is a 2.5-meter telescope mounted in a converted Boeing 747 aircraft, allowing it to perform observations above most of the infrared-absorbing water vapor in the atmosphere.

The survey concluded that SOFIA, which costs about $85 million a year to operate, doesn’t perform science commensurate with that level of spending, and is in some cases outperformed by much less expensive space missions.

“The survey committee has significant concerns about SOFIA, given its high cost and modest scientific productivity,” the report stated. It noted that, in its first six years of regular operations, SOFIA generated 178 scientific papers that were cited 1,242 times in other papers. That’s far less than other missions with similar operating costs, like the Hubble Space Telescope and Chandra X-Ray Observatory, or even less expensive missions like the TESS exoplanet spacecraft. “Relative to its cost, SOFIA has not been scientifically productive or impactful over its duration.”

The concerns about cost versus scientific productivity are not new, and led NASA in 2018 and 2019 to commission two studies about both its science and operations. That resulted in changes that has increased the number of papers published per year by 50%, the report noted.

Those results, though, were not convincing the decadal survey. “The survey committee found no evidence that SOFIA could, in fact, transition to a significantly more productive future,” the report stated, calling recent improvements only “modest” in scale with little prospect for future improvements. “Thus, the survey committee found no path by which SOFIA can significantly increase its scientific output or relevance to a degree that is commensurate with its cost.”

The report recommended that NASA end operations by 2023, which it said was consistent with the plan that the agency presented to the decadal survey steering committee.

NASA proposed terminating SOFIA in its fiscal year 2021 budget request, only to have Congress fully fund the program in the final omnibus spending bill last December. The agency again proposed terminating SOFIA in its fiscal year 2022 budget request in May. “Dramatic improvement in SOFIA’s scientific productivity is not expected,” the agency said in its budget documents.

While a House spending bill would again restore funding for SOFIA, the Senate version of the bill is silent on the program, keeping the program’s future uncertain. “We won’t know that until the House and Senate conference on their separate FY22 budget markups and a reconciled bill is voted on by both houses,” Paul Hertz, director of NASA’s astrophysics division, said at a Nov. 8 meeting of the Committee on Astronomy and Astrophysics of the Space Studies Board.

The Universities Space Research Association (USRA), which operates SOFIA for NASA, argues that the decadal survey reached its conclusion based on older information and “unfortunately did not take into account SOFIA’s latest scientific discoveries,” said Suraiya Farukhi, director of external communications for USRA. Margaret Meixner, director for science mission operations for SOFIA, offered to provide the decadal survey steering committee an update but was unable to do so, she said.

Farukhi added that SOFIA will participate in the next senior review of NASA astrophysics missions. “Our proposal to the senior review will show how SOFIA has not only become more scientifically productive but also outlines a path to further increase its science productivity and impact,” she said.

Hertz said SOFIA’s inclusion in the senior review is still pending. “We have made no decision to date whether or not SOFIA will be in the senior review given the recommendation of the decadal survey,” he said. Asked by a committee member when NASA will make that decision, he responded, “we need to make that relatively quickly to let the SOFIA team know.”

Quelle: SN