The U.S. Air Force budget request for fiscal year 2015 includes a $215 million line item for the Space Fence, an advanced space surveillance system expected to be put under contract in the coming months.

Lockheed Martin and Raytheon have developed competing designs for the next-generation Space Fence, a system of ground-based radars that would be capable of tracking golfball-sized objects in Earth orbit.

Air Force officials have said the multibillion-dollar contract award, delayed from last year, is now expected in mid-May.

Previously, the Space Fence was included under a broader budget account called Space Situational Awareness. The Air Force expects to spend $731 million on the program through 2019, budget documents show.

In 2013, the Air Force reduced the numbed of planned Space Fence radar sites from two to one, although the development contracts include the option for a second site, if needed, the Government Accountability Office said in congressional testimony March 12. The first site is expected to be built on the Kwajalein Atoll in the Pacific.

The latest Air Force budget documents nonetheless describe Space Fence as “a system of two land-based radars.”

The budget also includes outyear funding for a follow-on to the Space-Based Space Surveillance satellite launched in 2015. Although no funds are allocated in 2015, a combined $261 million is projected for 2016-2019 for the program.

“The follow-on program is being developed; however, it will not be launched until 2021 based on available funding,” Gen. William Shelton, commander of Air Force Space Command, said March 12 in written congressional testimony. “The result is a potential 4-year gap in this crucial space-based coverage, which will limit our ability to maintain timely custody of threats to our satellites in geosynchronous orbits.”