The first of the U.S. Air Force‘s new missile-warning sensor payloads is performing well after completing an initial round of performance checkouts, the Air Force’s space czar said Nov. 29.

The Space Based Infrared Systems (SBIRS) High sensor payload is "meeting or exceeding our expectations," Ronald Sega, under secretary of the Air Force, told reporters at a Defense Writers Group breakfast attended by sister publication Defense Daily.

The sophisticated sensors are carried on a classified intelligence satellite launched in June and now operating in a highly elliptical orbit (HEO). The sensors are able to detect ballistic missiles from northern polar regions, according to Lockheed Martin, which leads the SBIRS High industry team. Northrop Grumman builds the sensors.

The Air Force announced Nov. 17 that the initial checkout of the sensors had been completed. The Space and Missile Systems Center (SMC), which oversees the SBIRS High program, said these activities focused on the calibration of the payload’s infrared sensors as well as line-of-sight testing.

The HEO 1 payload is still in the checkout phase, the Air Force says. In fact, the payload may not be fully operationally certified until mid 2008, according to SMC.

However, the on-orbit success of the payload to date is already increasing confidence in the design of the remaining sensors that are now being built for two SBIRS High satellites that will operate in geosynchronous orbit (GEO), senior Air Force officials said. Technical and integration challenges with the sensors caused schedule delays and significant cost growth to the SBIRS High program in the past.

"Many elements of that sensor that we now are actually testing and getting real data with are in fact the same one that are in the GEO sensor that is going through test and checkout assembly," Lt. Gen. Michael Hamel, SMC’s commander, said during a Nov. 17 meeting with reporters. "So it is a very positive step in terms of validating the designs."

The SBIRS High program wad restructured in 2005 after the program breached congressionally mandated limits on cost growth. The current program of record is for two HEO payloads and three GEO satellites — down from the five GEO satellites originally planned — in addition to the SBIRS High ground element that has been operational since 2001.

The Lockheed Martin-led team is under contract to provide the two HEO payloads and the first two GEO satellites. HEO 2, which like HEO 1 is destined for a classified intelligence satellite, has been delivered to the Air Force for integration on the host spacecraft.

The first launch of a GEO satellite is on track for late 2008, Air Force and industry officials say.

As part of the SBIRS High restructure, the Air Force has begun an Alternative Infrared Satellite System (AIRSS) program to mature new sensor technologies as a means of mitigating the chances that additional setbacks in the SBIRS High program could lead to a gap in U.S. missile launch warning capabilities.

Under AIRSS, the service awarded Raytheon a $54 million contract in September and SAIC a $25 million deal in October to develop prototype sensors that could eventually complement or replace the SBIRS High sensors.

Air Force space officials have said they want to be in the position around early 2008 to decide whether to procure the third SBIRS High GEO satellite or transition to the AIRSS, or perhaps even incorporate AIRSS sensors on later SBIRS High spacecraft.

The Air Force has a requirement for at least four GEO-based warning satellites to replace the current Defense Support Program missile warning constellation.

Sega said the service is mulling the best path forward for leveraging the new sensor technologies more quickly, noting that it "is a little bit early right now" to know the answers. "We are getting better and better at [infrared] detectors, not only for SBIRS, but for astronomy and all kinds of things," he said. "The question is how do you take advantage of that and insert them."

In addition to providing warning of ballistic missile launches, SBIRS sensors will support missile defense and supply technical intelligence and battlespace information to increase the situational awareness of combatant commanders, according to the Air Force.

The sensors will have improved sensitivity compared to the payloads on DSP satellites, the Air Force says.