Having been relegated to Plan B status in the Pentagon’s effort to field a boost-phase missile defense capability, the Kinetic Energy Interceptor (KEI) program now is focused almost exclusively on demonstrating a super-fast, highly maneuverable booster potentially able to knock down enemy missiles as they lift off.

Previously planned engineering work aimed at having a production-ready design around the end of the decade has been stripped out of the program, according to U.S. Missile Defense Agency (MDA) officials and budget documents.

The key milestone in the restructured program is a 2008 flight test of the booster. At around the same time, the Airborne Laser — the front-runner for the boost-phase portion of the MDA’s planned multilayered missile shield — will attempt to shoot down a target missile. The results of those tests could determine the fate of both programs.

One year ago, it appeared that the Airborne Laser, a modified Boeing 747 aircraft equipped with a high-energy laser, was a good bet for cancellation. In an interview last June, U.S. Air Force Lt. Gen. Ronald Kadish, who at the time was the MDA director, said the program might be killed if it did not achieve key test milestones that were scheduled for late 2004.

The Airborne Laser came through, however, and it was the KEI program that bore the brunt of a roughly $1 billion reduction to the MDA’s 2006 budget request ordered late last year by the Pentagon leadership. The MDA is seeking $218 million for the KEI program for 2006, far less than the $1 billion it anticipated it would be asking for just one year ago.

“We have established the Airborne Laser as the primary boost-phase defense element,” Air Force Lt. Gen. Henry “Trey” Obering, the MDA director, said in written testimony to Congress this spring. “…We restructured the Kinetic Energy Interceptor activity as risk mitigation for the Airborne Laser and focused it on development of a land-based mobile, high-acceleration booster.”

Obering said in his remarks that the MDA will not know for two to three years whether either system will work. But he added, “With the recent successes we have had with [the Airborne Laser], we are now able to fine tune our boost-phase development work to better align it with our longer-term missile defense strategy of building a layered capability that has greater flexibility and mobility.”

When the MDA expected a billion-dollar KEI budget for 2006, plans called for doing the technology development work in parallel with the engineering necessary to have a system that could be produced and deployed. Documents accompanying the MDA’s 2005 budget request said the KEI program as structured by prime contractor Northrop Grumman featured an “unprecedented mix of program content” including risk reduction, and design of production lines for the interceptor, launcher and battle management system.

The restructured program defers major investments in operational KEI capabilities to focus on the risk reduction and technology demonstration work, according to an MDA official. The test program features 10 static firings of KEI booster motors, the 2008 test of the integrated interceptor booster and laboratory testing of the kill vehicle hardware, the official said.

In a written response to questions, Craig Staresinich, vice president and general manager for the KEI program at Northrop Grumman Mission Systems of Fair Lakes, Va., said static test firings of the booster’s second- and first-stage motors are slated for this August and January 2006, respectively.

Raytheon Co. is Northrop Grumman’s main subcontractor on the KEI effort, with responsibility for the kill vehicle and overall interceptor integration. The kill vehicle draws on the seeker and avionics technology for the Standard Missile 3 sea-based interceptor, and the divert-and-attitude-control system for the Ground Based Midcourse Defense system’s Exoatmospheric Kill Vehicle.

According to documents accompanying the MDA’s 2006 budget request, the KEI seeker design has “evolved from a one-color to two-color” system to better differentiate between a missile body and its exhaust plume.

Sara Hammond, a spokeswoman for Raytheon Missile Systems in Tucson, Ariz., said the company’s KEI plan has been “minimally impacted” by the reduced spending profile. She noted that the kill vehicle draws upon mature technologies from the Standard Missile 3 and Exoatmospheric Kill Vehicle, both of which are Raytheon programs.

Still, the idea that the MDA could choose between the KEI and the Airborne Laser based on the 2008 tests strikes some as odd. The Airborne Laser must shoot down a target missile, whereas all the KEI booster must do is demonstrate its potential for doing so. The latest KEI plan does not call for an intercept test until 2010 or 2011.

Kerry Gildea, a spokeswoman for Boeing Missile Defense Systems of Arlington, Va., said the Airborne Laser is the “most mature option available” for boost-phase defense.

But that could prove to be a liability, said Loren Thompson, chief operating officer at the Lexington Institute, a think tank here. More-mature systems generally encounter more snags, making newer concepts seem more appealing, he said.

An industry source was more blunt about a possible showdown in 2008: “It’s like having one chef make a peanut butter and jelly sandwich, and another other one make an eight course meal, and whichever is done fastest wins.”