WASHINGTON — After nearly a decade of delay, the U.S. Air Force tentatively plans to launch its first dedicated Space Based Infrared System (SBIRS) missile warning satellite April 30 but faces a narrow launch window, which means any additional hiccups in the program likely would push the mission into 2012, a service official said.

At the same time, the Air Force is renegotiating its SBIRS prime contract with Lockheed Martin Space Systems of Sunnyvale, Calif., to make improvements to the system’s ground infrastructure and data processing algorithms through the latter part of the decade ahead, Col. Roger Teague, commander of the Space Based Infrared Systems Wing at Air Force Space and Missile Systems Center in Los Angeles, said in an Oct. 13 interview.

With the first satellite nearing completion of its final test activities, Air Force officials decided the week of Oct. 4 to plan for an April 30 launch aboard an Atlas 5 rocket from Cape Canaveral Air Force Station, Fla., Teague said. But because NASA has two planetary missions scheduled to launch next summer and fall that will require the same Atlas 5 launch pad and crew that will launch SBIRS, the Air Force has virtually no margin for error.

NASA must launch its Juno mission to Jupiter between Aug. 5 and Aug. 23, or wait another 13 months for the next opportunity. Then NASA must launch the flagship-class Mars Science Laboratory mission in November or else wait two years for the next opportunity.

That means that if SBIRS is not launched by early May, the next opportunity likely will not come before January or February 2012 because the Atlas 5 is the only rocket in the U.S. fleet that meets the SBIRS deployment requirements, Air Force spokeswoman LaGina Jackson said in an e-mailed response to questions.

Lockheed Martin is under contract to deliver four dedicated SBIRS satellites that will operate in geosynchronous orbit, four SBIRS infrared payloads to be hosted on classified  satellites in highly elliptical orbits, and the associated ground control and data processing systems. The first two elliptical-orbit payloads and the ground systems are operational.

The first of the geosynchronous satellites originally was slated to launch in 2002, and Pentagon leaders in recent years have expressed frustration and concern with the delays given the finite lifespan of the legacy Defense Support Program (DSP) missile warning constellation. Air Force Gen. Kevin Chilton, commander of U.S. Strategic Command, on Sept. 13 reiterated his desire to develop a gap-filler missile warning capability to ensure full coverage during the transition from DSP to SBIRS.

“In 2008, given the delays in the SBIRS program which is designed to replace today’s DSP constellation, I raised concern, I believe at this podium, over the sustainment of the on-orbit capability,” Chilton said at an Air Force Association conference here. “I was told not to worry; it would launch in the fall of 2009.

“The fall of 2009 I raised the same concerns and pointed out that we were quickly approaching a point where we required 100 percent launch success of our first two satellites in order to sustain the capability and meet the requirements of United States Strategic Command to provide this element of the strategic deterrent. We did nothing. I was told we would launch in the fall of 2010.

“It’s now fall of 2010 and [the first SBIRS satellite] is not scheduled to launch before next summer. In sum, it has slipped two-and-a-half years in two years.”

For the last three years, the first SBIRS satellite has been held up primarily by flight software problems. Large numbers of anomalies were popping up during testing in 2007, and the decision was made to scrap the existing software and essentially start from scratch.

Development of the new software has taken longer than anticipated, but the Air Force believes the version that was delivered in August will be the final iteration. The software has completed about 90 percent of an exhaustive flight qualification process, with no problems so far, said Jeff Smith, Lockheed Martin’s SBIRS vice president and program manager.

“We had a new design and development of our flight software that in the end has proven to be very robust, very stable and of high quality,” Teague said. “…What you’ve seen frankly is the most robust software development and qualification program among all [Space and Missile Systems Center] programs in SBIRS. And that was necessary due to the critical mission that this satellite will satisfy.”

The first dedicated SBIRS satellite has completed all of its environmental testing and is awaiting the installation of its solar arrays, thermal blankets and sun shield, Teague said. If the software qualification testing remains on track, a final decision on whether to proceed with launch is expected in January, he said.

The Air Force so far has spent $6.8 billion on Lockheed Martin’s original SBIRS prime development contract, which includes the first two geosynchronous satellites, the first two highly elliptical orbiting payloads and the ground systems. The total cost to complete this contract is not yet known because negotiations are under way to increase the scope of the company’s work, Teague said. By the end of the year, the service hopes to have one aspect of the contract finalized for which Lockheed Martin will modernize the SBIRS ground infrastructure through 2014 or 2015. The other part of the contract should be negotiated and signed by summer 2011, which will allow the company to continue developing ground software to better exploit SBIRS data through 2017 or 2018, Teague said.

“We’ve learned a lot [from the SBIRS highly elliptical orbiting payloads] about what we expect we will be able to do with our [geosynchronous] birds. From that aspect, we got together with our command leads and took an opportunity to redesign and rearchitect our ground infrastructure. We’re in the process of renegotiating that with Lockheed Martin right now.”

The Air Force in June finalized a separate $3 billion SBIRS production contract with Lockheed Martin to build the third and fourth geosynchronous satellites and third and fourth highly elliptical orbiting payloads and ground system modifications.