German space officials were pressing NASA last week to honour US commitment to the SOFIA (Stratospheric Observatory for Infrared Astronomy) project, following rumours that the agency may pull funding for the airborne observatory before its first flight.

SOFIA, which has been in the planning stage for more than two decades, will place a 2.5-metre telescope — similar in size to the Hubble Space Telescope — onboard a modified 747 aeroplane. This will fly above most of the water vapour in the atmosphere that blocks incoming infrared radiation. A successor to the Kuiper Airborne Observatory that flew until 1995, SOFIA bridges the gap between ground-based telescopes and infrared satellites such as the Spitzer Space Telescope. NASA will pay 80% of the bill, or about $500 million, as well as most of the operational costs, with Germany supplying the telescope.

The German card has been played — we’ve made very clear how important this is to us.

The first test flight of the long-delayed project was scheduled for this October, with science flights beginning in 2008. But at the American Astronomical Society meeting in Washington DC last month, project scientists heard rumours that NASA planned to eliminate funding for SOFIA in 2006 and 2007, with an eye to killing the project outright.

David Black, president of the Universities Space Research Association in Columbia, Maryland, which manages SOFIA for NASA, says the information came from many sources and is credible enough to be taken seriously. NASA spokeswoman Erica Hupp says the agency will not comment on SOFIA's status until the agency's 2007 budget request is unveiled on 6 February.

Alarmed by what they heard, German space officials last week complained to their NASA counterparts. Sigmar Wittig, chairman of the board for the German Aerospace Center, DLR, pleaded SOFIA's case with NASA administrator Mike Griffin, as well as with deputy administrator Shana Dale, who was in Germany conferring with science ministers and legislators. “The German card has been played,” says Reinhard Genzel of the Max Planck Institute for Extraterrestrial Physics in Garching, a co-investigator for one of SOFIA's planned science instruments. “We've made very clear how important this is to us.” The German investment of nearly US$100 million in SOFIA makes it the country's largest collaborative space project outside the European Space Agency.

The German pressure, along with queries to NASA from members of the US Congress, may already have had an effect. “They're still working on it within NASA,” says astrophysicist Eric Becklin of the University of California, Los Angeles, the SOFIA chief scientist. Although he was “prepared for the worst” earlier last month, Becklin now says of NASA's budget request: “We don't really know what's going to come.”

Cancelling such a high-profile project so late in its development would be highly unusual. But NASA science managers are desperate to contain costs these days, and SOFIA's 20-year operational budget would make a tempting target. Having added substantially to the project's staff at NASA's Ames Research Center in California — partly to satisfy government-imposed safety requirements for flying the 747 — NASA is facing a lifetime operational budget for SOFIA that could top $1 billion. “We are definitely looking at ways to cut the operations budget,” says Becklin.