COLORADO SPRINGS, Colo. — The U.S. Air Force will spend the next 18 months working with industry to design an upgraded, ground-based space surveillance system expected to begin tracking golfball-sized space objects in 2015, said Gary Payton, undersecretary of the Air Force for Space.

The current Space Fence, a key element of the Air Force’s broader Space Surveillance Network, consists of nine very high frequency (VHF) radar sites located across the southern United States; it can track objects roughly the size of a baseball. The upgraded Fence likely would feature S-band radars at three sites, at least one of which would be located outside the country.

In response to a request for proposals the Air Force issued in March, Lockheed Martin Corp., Northrop Grumman Corp. and Raytheon Co. submitted proposals for 18-month, fixed-price contracts to further develop the Space Fence concept. The Air Force intends to award up to three contracts in July.

The three companies completed work in August 2006 on $1 million contracts to explore options for upgrading the Space Fence.

Payton said he would like to select a prime contractor for the effort by 2012.

The Space Fence, which Payton said has been funded, plays a prominent role in Air Force plans to expand its ability to track and catalog objects that could pose a threat to operational spacecraft. In the wake of the Feb. 10 orbital collision that destroyed an Iridium communications satellite, the Air Force brought in additional analysts to double the number of space objects closely monitored by the Air Force-led Joint Space Operations Center (JSPOC) at Vandenberg Air Force Base in California. JSPOC now closely watches about 330 of the 19,000 known space objects larger than 10 centimeters across, but wants to increase that number to include all 800 operational satellites capable of being maneuvered to avoid a collision.

The upgraded Space Fence is expected to dramatically increase the number of objects being tracked, said John Morse, Space Fence program director at Lockheed Martin Maritime Systems and Sensors of Moorestown, N.J.

“This new S-band Fence will go up as high as 100,000 or 120,000 objects,” Morse said. “The government certainly has raised the bar on what their expectations are.”

Payton said the industry teams will primarily look at S-band capabilities but other options will be considered.

“They’re looking at should it be S-band radar or should it be VHF or UHF, and should it be a radar that just looks straight up – literally a fence that things fly through – or should it be a radar that sweeps the horizon that things fly through,” Payton said during an April 2 press conference at the National Space Symposium here. “The cost estimates for this are wide; it’s huge differences in cost estimates so part of it will be affordability. Some of the designs are a lot more expensive than other designs and they are also more capable, and so there’s a lot of work in front of us on what kind of radar will it really be.”

By reducing the number of Space Fence tracking sites from nine to three, the Air Force hopes to realize significant savings on maintenance. The first of the new sites is expected to be operational by 2015, and while its location has not yet been decided, Payton raised Australia as a possibility.

“We’ve got a constantly improving relationship with Australia so if we could site it there – we haven’t committed to that yet – but that would be good geography,” Payton said.

Sites under consideration in the United States include Gila River, N.M.; Lake Kickapoo, Texas; and Jordan Lake, Ala.

One of the major challenges of increasing the number of space objects that can be observed and monitored is improving the capability to process and disseminate the information on the ground, said Richard Davis, director of special projects at Northrop Grumman’s Advanced Concepts and Technology division in Baltimore.

Part of the Air Force concept development contract includes looking at how the Space Surveillance Network would need to be upgraded to handle the dramatic increase in data.

“The good thing about Space Fence is you’re going to have this wonderful, high-quality data out there,” Davis said. “Now you’re going to have to sort that out so you have actionable intelligence.”

Officials of Raytheon Integrated Defense Systems of Tewksbury, Mass., declined to be interviewed. In a prepared statement provided by Raytheon spokeswoman Maureen Heard, the company touted its expertise in “engineering, sensing and global capabilities integration” as keys to the program. “We are confident that our proposal will be well received by our customer,” the statement said.