WASHINGTON — NASA and German space agency DLR announced April 28 they will end operations of an airborne astrophysics observatory in September.

The agencies said that flights of the Stratospheric Observatory for Infrared Astronomy (SOFIA), a Boeing 747 with a 2.7-meter infrared telescope mounted in its fuselage, will end no later than Sept. 30, at the conclusion of its current extended mission.

SOFIA’s future has been in question in recent years because of its high operating cost. NASA spends about $85 million a year on SOFIA, more than any other operational astrophysics mission except the Hubble Space Telescope. NASA proposed terminating funding for SOFIA in its fiscal year 2021 and 2022 budget proposals, only to have Congress restore funding.

The Astro2020 astrophysics decadal survey, published in November, recommended NASA shut down SOFIA, citing its high cost and limited scientific productivity. “Relative to its cost, SOFIA has not been scientifically productive or impactful over its duration,” the survey’s final report stated, concluding that NASA end SOFIA operations by 2023.

SOFIA officials at the Universities Space Research Association (USRA), which handles science operations, argued in January that the decadal survey based its conclusion on older information that did not reflect improvements in SOFIA’s scientific productivity, such as more observing time and an increase in publications.

NASA, though, again requested no funding for SOFIA in its fiscal year 2023 budget proposal released March 28. The agency needed an agreement with DLR, though, to move ahead with any termination of SOFIA because the German agency has a 20% share of the program and its costs.

The agencies did not offer details on how it will shut down SOFIA. “SOFIA will finish out its scheduled operations for the 2022 fiscal year, followed by an orderly shutdown,” NASA stated, with data it collected placed in online archives.

Suraiya Farukhi, director of external communications for USRA, told SpaceNews that the plans for ending SOFIA operations are under discussion with NASA, DLR and the Deutsches SOFIA Institut, USRA’s German partners on SOFIA. About 70 more SOFIA flights are planned, including more than 30 flights during a southern deployment in New Zealand.

She said more than 100 observing programs were selected in the most recent call for SOFIA proposals, called Cycle 9, and not all of them will be completed by the end of September. USRA solicited proposals earlier this year for a new round of SOFIA observations, Cycle 10, that was to begin in October 2022. Those proposals will be “kept on hold until further guidance from NASA,” she said.

“The cessation of SOFIA’s flight operations is by no means the end of German-American cooperation,” Thomas Zurbuchen, NASA associate administrator for science, said in a DLR statement. He said the agencies will hold a joint workshop this summer to identify potential new projects “in future scientific fields.”

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...