SAN JOSE — A senior U.S. Air Force acquisition officer said Lockheed Martin has made “tremendous progress” lately on a long-troubled missile warning satellite program, even as the service awarded the second of two contracts to develop an alternative sensor technology.

The service announced the week of Sept. 18 that it had awarded SAIC Corp. of San Diego, a contract worth $24 million to design and develop a missile warning sensor under the Alternative Infrared Satellite System (AIRSS) program, which was created earlier this year as insurance against more problems with the Space Based Infrared System (SBIRS) satellites that are being built by Lockheed Martin. The Air Force Sept. 5 awarded Raytheon Co. a $54 million AIRSS sensor contract.

Both SAIC and Raytheon will spend the next 18 months developing prototype infrared missile warning sensors that will be delivered to the Air Force for testing in 2008. The AIRSS sensors will incorporate infrared-detector and data processing technologies that were not available when the SBIRS program was put under contract in the mid 1990s.

It is far from clear, however, when the AIRSS sensor technology will find its way into the U.S. missile warning satellite architecture. The Air Force restructured the SBIRS program last year due to persistent developmental problems that drove its projected cost from $2 billion to roughly $10 billion. The restructuring reduced the number of dedicated SBIRS satellites the Air Force will purchase from five to no more than three and possibly only two.

In ordering the restructuring, Air Force Undersecretary Ronald Sega said the decision on whether the service would buy a third SBIRS satellite would hinge upon prime contractor Lockheed Martin’s progress on the first two. Lockheed Martin Space Systems of Sunnyvale, Calif., has completed several test milestones recently on the program and company officials have expressed confidence that the program is finally on track.

“We understand the Department of Defense’s need to explore new technologies to support the important mission of national missile warning and we support the government’s study effort to address future requirements and plans for this capability,” Lockheed Martin spokesman Steve Tatum said Sept. 21.

Lockheed Martin, Tatum said, is “relentlessly focused on achieving mission success on SBIRS.” The SBIRS spacecraft, he noted, “will provide significantly increased capabilities over the current Defense Support Program (DSP) by supporting four mission areas simultaneously, including missile warning, missile defense, technical intelligence and battlespace characterization.

Lt. Gen. Michael Hamel, commander of Air Force Space and Missile Systems Center in Los Angeles, which procures military space hardware, agreed that Lockheed Martin has made notable progress on the program.

Speaking at a press conference Sept. 19 here at the Space 2006 conference organized by the American Institute of Aeronautics and Astronautics, a professional association based in Reston, Va., Hamel said Lockheed Martin’s progress of late has given him confidence in the program. “I’m personally very satisfied with the progress we’ve made,” he said.

In an interview shortly after the press conference, Hamel declined to speculate about whether the Air Force ultimately will order a third SBIRS satellite, a decision that he acknowledged needs to be made in the spring of 2007 — well before either SAIC or Raytheon will have had the chance to demonstrate mastery of the AIRSS sensor technology.

During the press conference, Joanne Maguire, executive vice president of Lockheed Martin Space Systems, said the longer the Air Force waits to order a third SBIRS satellite, the more it is likely to cost. The company already has taken delivery of all of the components needed to build the first two SBIRS satellites, and the production lines for that hardware are winding down, she said. Interruptions in the production of hardware can drive up the cost of space programs dramatically.

During the interview, Hamel said it was prudent to initiate the AIRSS program under any circumstances given the technological advances that have occurred in the years since the SBIRS contract was awarded. “We need to be investing for the long term,” he said.

The SBIRS instrument actually has two sensors: one that performs scans covering roughly one third of the Earth’s surface; and one that focuses continuously on areas deemed to be likely sites of missile launches.

The AIRSS program is aimed at developing a sensor that has no moving parts and can stare continuously at the full third of the Earth’s surface, Hamel said. He likened the difference in the two technologies to that of vacuum tubes versus transistors in consumer electronics.

Air Force officials have previously acknowledged, however, that the AIRSS sensor will not be as capable as the SBIRS sensor, which is built by Northrop Grumman Electronic Systems in Azusa, Calif. The first two SBIRS sensors have been delivered to the U.S. government and are to be hosted aboard classified satellites operating in highly elliptical orbits.

The dedicated SBIRS satellites will operate on geosynchronous orbit. The first of those satellites, as well as its sensor, are expected to undergo thermal vacuum testing separately starting later this year. The satellite and sensor are slated to undergo testing as an integrated package next year in preparation for a planned late 2008 launch.

The United States relies today on the DSP satellites for missile warning. The last of those satellites is slated for launch in early 2007, and the outcome of that mission will be a factor in determining whether the Air Force procures a third SBIRS satellite before moving on to the AIRSS system, Hamel said.

Hamel said the Air Force intends to award one or more contracts in November for design work on the full SBIRS replacement satellite system, and that it would not necessarily incorporate whatever sensor Raytheon or SAIC come up with under the AIRSS program.

Hamel said he has encouraged industry to begin working together on concepts and partnership arrangements for the SBIRS follow-on system. He would not rule out the possibility that the AIRSS sensor would be hosted by a Lockheed Martin-supplied satellite platform similar to the one being used for SBIRS.

Hamel noted that the AIRSS satellites will have to operate with the SBIRS ground system, which has been in operation since November 2001.