The U.S. Air Force in its 2011 budget request will announce significant changes to the Third Generation Infrared Surveillance (TGIRS) missile warning technology development program, a top service official said.

TGIRS was originally conceived as a potential alternative to the long-troubled Space Based Infrared System (SBIRS), whose first dedicated satellite is almost a decade behind schedule. But as the Air Force became confident that SBIRS was finally on track, TGIRS became a technology demonstration effort that now has two main elements: an experimental sensor built by SAIC to be hosted aboard an SES Americom commercial communications satellite slated to launch in January 2011; and a Raytheon-built experimental sensor that the company recently was asked to qualify for spaceflight.

The SAIC instrument has been completed and its host satellite is under construction at Orbital Sciences Corp. During interviews Jan. 12, Orbital officials discussed the hosted payload demonstration and gave no indication that it would not go forward.

U.S. Air Force Gen. Robert Kehler, commander of Air Force Space Command, said significant changes are in store for TGIRS but was not specific.

“I think we’re going to find it significantly different,” Kehler said in a Jan. 20 media briefing. “We’ll still continue with some demonstration activities, and we’ll still continue to work with [Air Force Gen. Kevin Chilton, commander of U.S. Strategic Command], who’s got some concerns about what could happen here if we have another delay to SBIRS or if we have a launch failure or unforeseen circumstances. So we are looking at, can we leverage [the Operationally Responsive Space Office]? Are there other things we can do? There’s more work to be done here.”

Industry sources said Strategic Command recently tapped the Pentagon’s Operationally Responsive Space Office to respond to an urgent need for missile warning capability. Chilton would not comment on the situation in a Jan. 20 media briefing.

Meanwhile, Kehler expressed optimism for the long-delayed SBIRS program.

“We’re very encouraged by the progress on SBIRS Geo-1, which has come through thermal [vacuum testing] very cleanly. We now have a way forward to do some hardware replacement and finish up some certification of the operational software and take it through some final integration tests. So we are hopeful that by the end of this year we will have Geo-1 out of the factory and headed toward a launch pad.”