The Pentagon's No. 1 supplier, Lockheed Martin Corp (LMT), has won a $915 million contract to develop a ground-based radar for tracking objects in space for the U.S. Air Force, beating out a bid from Raytheon Co. (RTN).

The fixed-price contract, which includes an incentive fee, was announced late on Monday by the Pentagon in its daily digest of major contract awards.

U.S. military officials have underscored the importance of the Air Force's Space Fence program, given the growing number of countries operating satellites in space, China's work on anti-satellite weapons, and the huge amount of debris in orbit.

The new program will allow the Air Force to increase sharply its ability to track "space junk" and other smaller objects in space. Currently the Air Force tracks about 23,000 of an estimated 500,000 objects in space, but the new program would allow it to track hundreds of thousands of additional objects.

Plans call for the new system to be based on Kwajalein Atoll in the Marshall Islands, about 2,100 miles southwest of Honolulu, Hawaii, and to start operating in September 2018.

Raytheon said it had been notified about the Air Force's decision, but said it would be inappropriate to comment further until after it receives a post-decision debrief from Air Force officials. A company spokesman declined comment on whether the company would protest the decision. 

(Reporting by Andrea Shalal; editing by Meredith Mazzilli and Matthew Lewis)