The U.S. Air Force will not have reliable cost estimates until early next decade for its proposed constellation of radar satellites that would detect movement on the ground , according to acting service Secretary Peter B. Teets.

Key details of the Space Radar, such as the number of satellites in the constellation and its operating orbit, will not become clear until sometime between 2010 and 2014, Teets told the House Armed Services strategic forces subcommittee March 9. Teets also is the undersecretary of the Air Force and director of the U.S. National Reconnaissance Office.

The Air Force has asked Congress for $226 million in 2006 for the Space Radar, and projects spending about $5.3 billion on the effort through 2011. The bulk of that funding will go toward a two-satellite demonstration mission that the Air Force hopes to launch in 2008, and toward designing the first operational Space Radar satellite, which would launch around 2015, Teets said.

The 2008 demonstration, featuring satellites roughly one quarter the size of the operational craft , will help reduce technical risks and enable the Air Force to make better-informed programmatic decisions, Teets said .

Lawmakers on both sides of the political aisle have expressed concerns about the Space Radar’s potential cost, and Congress last year slashed the Air Force’s $328 million request for the program in 2005 to $75 million.

During the hearing, Rep. Silvestre Reyes (D-Texas), the subcommittee’s ranking minority member, noted that action and asked Teets if the service had set a limit for the total cost of a Space Radar constellation.

Air Force budget projections last year indicated that a nine-satellite constellation would cost about $34 billion.

Teets said no cost cap has been established but noted that the Space Radar as envisioned today likely would consist of fewer than nine satellites and be part of a broader surveillance system that also would rely on aerial reconnaissance assets. The Air Force got ahead of itself when it set its sights on a nine-satellite constellation in low Earth orbit that would launch starting in 2012, he said.

The Air Force is keeping its options open on orbital altitudes for the Space Radar, Teets said. Air Force officials have in the past raised the possibility of placing the satellites in medium-altitude orbit, which would give the system wider coverage with fewer spacecraft. However, the higher orbit would require more powerful sensors that may not be ready by the middle of the next decade.

The Air Force also is toning down its statements regarding the Space Radar’s capabilities. Air Force officials in past years have talked about using the satellites to track moving targets on the ground on a nearly continuous basis while also providing high-resolution imagery to the intelligence community.

But continuous global tracking is no longer in the Space Radar program brochure; notification of movement on the ground is now the system’s defining capability. Some congressional staffers are skeptical of the military utility of the more limited capability, especially at a cost of tens of millions of dollars.

U.S. Navy Vice Adm. Joseph Sestak, deputy chief of naval operations for warfare requirements and programs, said the Space Radar as now advertised could play an important role in protecting ships from mobile missiles based on shore. When movement near a shoreline is detected, aircraft could be dispatched to take out any missiles that may be in the area, thereby reducing the number of potential incoming warheads that shipboard defense systems would have to deal with, he said.

Rep. Terry Everett (R-Ala.), chairman of the strategic forces subcommittee, expressed concerns with cost growth on military space programs in general, but said he was pleased to see the Air Force and National Reconnaissance Office cooperating on the Space Radar effort.

Military and intelligence officials have clashed in the past over the kinds of capabilities the system should have, and how it would be operated. Defense Secretary Donald Rumsfeld and CIA Director Porter Goss in late January signed a memo designating the Space Radar as the replacement for the radar component of the Future Imagery Architecture, a classified series of satellites being developed by Boeing Co. for the National Reconnaissance Office.

Everett noted that the U.S. government cannot afford to invest in separate radar satellite constellations.