Deep-Space Radar Construction Delayed, GAO Says

The Space Force approved the first of three deep-space radars for early operational use last fall, but construction delays at the ground-based radar site in Western Australia are holding up the program, according to a government watchdog.

A Government Accountability Office report released July 2 highlights progress on the Deep-Space Advanced Radar Capability—known as DARC—as the program’s first radar undergoes testing. The Space Force approved the radar for early use last September, clearing the way for operations before testing is complete.

But “unanticipated cost growth” and delays at the first radar site could have ripple effects, the report said, noting that construction at a third site had been pushed back at least 10 months to July 2030.

Program managers cited “unanticipated cost growth for Site 1 due to modifications for various issues, including foreign country requirements,” GAO said. “This has resulted in additional schedule slip for Site 3, delaying Site 3’s construction start by 10 months and operational acceptance by 4 months.”

The Space Force uses a mix of satellites and ground-based systems to monitor orbital activity in space and to detect and warn of potential missile threats—both key missions for the service and U.S. Space Command. Space domain awareness, or the ability to know what is going on and where in space, is foundational to the military’s ability to operate freely in space and to perform core missions like space control.

DARC is a joint effort between the U.S., Australia, and the United Kingdom to use ground-based radars to track objects in geosynchronous orbit, up to 22,000 miles above Earth. The radars will provide 24/7, all-weather tracking, and once all three sites are online, will give the U.S. and its allies a continuous view of the entire GEO belt—greater coverage than is now possible with any other ground-based system. Under the pact, the Space Force is leading development, but the agreement allows the U.K. and Australia to operate and host the sites and participate in joint operations and exercises.

Northrop Grumman is on contract to build the first two facilities—one in Western Australia and a second in Wales. The Space Force hasn’t announced the location of the third site, which is expected to be in the U.S. and also built by Northrop, with a contract expected later this year or in early 2027.

The first DARC site is on a path toward operational acceptance early next year, and construction of the second is slated for next April. All three sites should be online by December 2032, according to GAO.

The Space Force indicated in 2025 that it was considering changing course on the DARC acquisition strategy, including potentially cancelling the third site. But its fiscal 2027 budget request funded the full program. That includes $442 million in fiscal ’27 and another $1.6 billion through fiscal ’31. That’s enough to fund the remaining operational testing slate for the first DARC site and pre-construction work at the Wales location. If approved, it will also allow the program office to start engineering and design for the U.S.-based radar and coordinate the necessary Federal Aviation Administration approvals.