WASHINGTON — A f ter a brush with cancellation early this year, the U.S.-German SOFIA flying astronomical observatory has a new lease on life and a fresh paint job. But before the telescope-equipped jetliner can begin initial science operations, NASA says it must first undergo several years of intensive flight testing.

The Stratospheric Observatory for Infrared Astronomy (SOFIA), in development for the past decade, is slated to take to the skies for the first time this winter. The modified Boeing 747 is due to make a series of brief checkout flights over Waco, Texas, before departing by late February for its new home at NASA’s Dryden Flight Research Center north of Los Angeles.

NASA intends to spend at least three years putting the SOFIA aircraft through its paces before allowing researchers to use the flying observatory’s German-supplied infrared telescope for the first time. Observation time, however, is expected to be limited until NASA completes another two years of flight testing and declares SOFIA operational.

Ray Taylor, the NASA program executive for SOFIA, said full-fledged science operations could begin as soon as 2012 assuming the final two years of shakedown flights go well.

“The science phase comes later now,” Taylor said in an Oct. 12 interview. “In front of it is going to be more development time and more development funding.”

NASA has spent roughly $485 million on SOFIA since awarding the prime contract for the project to Columbia, Md.-based Universities Space Research Association in December 1996. Taylor said NASA expects to spend another $250 million to $350 million on SOFIA before declaring it operational sometime early in the next decade.

Universities Space Research Association President David Black, who fought hard to save SOFIA from cancellation earlier this year, said he was disappointed with how NASA restructured the program.

“We are disappointed that the solution NASA has come up with is going to add extra cost and delay,” said Black. “We are going to continue to work with NASA to see if we can help find ways to pull that back.”

Black said estimates put forward by the program late last year pegged the cost to complete SOFIA at $150 million with the first science flight slated for mid-2008.

NASA officials, however, doubted those estimates and called for an independent program review in April 2006 to sort out what it would take to finish and fly SOFIA, which was already over budget and several years behind schedule.

In February, well before that review had even begun, NASA sent Congress a 2007 budget request that included no money for SOFIA. The move, widely seen as a de facto cancellation, shocked astronomers and angered NASA’s German partners. NASA came under immediate fire from SOFIA backers and their allies in Congress. NASA officials said they would hold off making a final decision about SOFIA until getting the results of the independent review.

That review, headed by former Dryden Flight Research Center director Kenneth Szalai, wrapped up in late spring and found no insurmountable technical or programmatic hurdles to completing SOFIA. NASA announced this summer SOFIA would be going forward but that responsibility for flight testing the aircraft would shift from Ames Research Center — which has long managed the program — to Dryden, the agency’s primary flight test facility.

Black, who is stepping down as Universities Space Research Association president in January, said he was glad SOFIA is going forward, but worries that inserting Dryden into the program is driving up costs.

“I think the reason it’s going to cost more is that with two centers involved now there will be more civil servants involved in the program,” he said.

Black also questioned the lengthy series of flight tests Dryden intends to conduct before declaring SOFIA operational.

“Dryden is taking a very conservative, perhaps unnecessarily so, approach to flight tests,” Black said. “This is not an experimental aircraft.”

Black said previous plans called for leaving flight testing largely in the hands of SOFIA’s builder, Waco, Texas-based L3 Communications and Integrated Systems, which was working closely with the Federal Aviation Administration on a certification plan for SOFIA.

Taylor said the lengthier flight test program now planned is warranted given SOFIA’s relatively high operating altitude — 39,000 to 45,000 feet — and the fact that the aircraft’s 2.5-meter telescope sits behind a large retractable door that must remain open during flight in order for the telescope to do its job.

“This is the largest hole that has ever been put into the structure of a 747,” Taylor said.

Taylor said that Dryden has the necessary expertise to test an aircraft like SOFIA. “We are in a new domain here with the size of the aperture on the airplane.”

After arriving at Dryden, SOFIA will spend the remainder of 2007 conducting so-called door-closed flight tests. Each test is intended to take SOFIA closer to its operating altitude. “Because SOFIA flies at a very high altitude there is a lot of flight envelope to clear,” Taylor said. “That is why that phase of flight testing does take time.”

Starting in 2008, Taylor said, NASA plans to crack SOFIA’s door open for the first time and see how it responds under various flight conditions. “Open door testing gets done by the end of 2009,” he said. “This has to be done very carefully in order for it to be done safely. That’s a big part of the program — ensuring safety through all these flight tests.”

If all goes well, Taylor said, NASA expects to make some initial observations with the telescope starting in 2010 as part of the final phases of flight testing. After this “engineering shakeout phase,” which Taylor expects to last “a couple of years,” SOFIA could be deemed operational with its flights dedicated to collecting science.

Taylor was less specific on the question of when SOFIA might fly its first group of teachers, one of the long standing goals for the program. “We don’t have anything pinned down on that.”

Another question still to be determined, according to Taylor, is whether SOFIA stays at Dryden once declared operational, or moves back to Ames. “Science operations stay at Ames Research Center pending an independent review on how to most cost effectively do science operations,” he said. “That independent review is planned for next year. “

Meanwhile, lawmakers who urged NASA to stick with SOFIA or at least give it a fair hearing before canceling it, are keeping a close eye on how the restructured program plays out.

An aide to one such lawmaker said it appears that the price of saving SOFIA was finding more work for Dryden, which could otherwise find itself with a dearth of flight testing to do in an era of declining NASA aeronautics budgets.

“This has become a jobs program for Dryden to pay for a lot of uncovered work force,” the aide said. “It’s a bargain with the devil: keep the program alive, but at additional cost and schedule.”

Taylor said he did not know how many civil servants NASA had assigned to the program.