A U.S. government auditor says the long-troubled Space Based Infrared System (SBIRS) is not out of the wood yet despite recent optimistic assessments of progress on the missile-warning program by the U.S. Air Force and prime contractor Lockheed Martin.

In written testimony submitted April 19 to the Senate Armed Services strategic forces subcommittee, Cristina T. Chaplain , head of acquisition and sourcing management at the U.S. Government Accountability Office (GAO), said the restructured SBIRS program “still faces considerable risks.” She said the program is “is diverging from cost and schedule targets just months after rebaselining due to problems related to assembly, integration, and testing,” adding that Lockheed Martin Space Systems has been overly optimistic regarding its ability to resolve the issues.

Chaplain also said reports from the Defense Contract Management Agency show that SBIRS software development efforts are behind schedule “by as much as 32 percent.”

In a restructuring undertaken in 2005 due to persistent cost growth and technical problems, the Air Force reduced its planned purchase of dedicated SBIRS satellites from five to no more than three. A decision on whether to procure a third SBIRS satellite is expected this summer.

However, senior Air Force officials have been vocal about the program’s progress in recent months, suggesting that the purchase of a third satellite is likely. Some Air Force officials have gone even further, suggesting that the service ultimately could go back to the original plan of buying five dedicated SBIRS satellites.

Chaplain also said Lockheed Martin is burning through the program’s reserves much more quickly than planned. The company spent about $66 million, or 28 percent of the reserve from April 2006 to November 2006, she said.

“This reserve is designed to last until 2012, but at the current rate, is likely to be depleted by May 2008. If this trend continues, $500 million in additional reserve will be needed,” she said .

Lockheed Martin spokesman Chip Manor deferred program cost questions to the Air Force. Air Force Space and Missile Systems Center did not respond to questions by press time.