WASHINGTON — The US Air Force last week awarded Northrop Grumman and Raytheon two sole-source contracts to mature radar designs for the Joint Surveillance Target Attack Radar System, a crucial step in the ongoing effort to recapitalize the service's ground surveillance fleet.

Northrop won a $70 million contract to reduce risk on its solution for a long-range, wide-area surveillance radar planned to equip the new JSTARS, while Raytheon nabbed a $60 million contract for similar work on a competing solution, the Pentagon announced March 24. Work on both will be completed by Sept. 30, 2017.

The two contractors have received $7.5 million each in research, development, test and evaluation funds to begin maturing their competing radars ahead of an expected down select to one supplier.

The Air Force's effort to develop a modern active electronically scanned array, or AESA, radar for the next-generation JSTARS is key to the recapitalization effort. The legacy E-8C JSTARS, identified by a long, canoe-shaped space under the forward fuselage that houses a 24-foot radar, tracks movement in the battle space and relays tactical pictures to ground and air theater commanders.

The use of a modern AESA radar will allow the JSTARS recapitalization to fulfill the mission while operating on a much smaller, business jet airframe, according to the Air Force.

Meanwhile, three distinct industry teams are vying to build the JSTARS airframe. Separately from the radar competition, Northrop is teamed with Gulfstream and its G550 business jet, with L-3 helping with integration. Lockheed Martin is working with Bombardier on a proposal based on the Canadian company's Global 6,000 business jet. And Boeing is offering a modified version of its 737-700 commercial airliner.

The three teams are currently moving forward with additional pre-engineering, manufacturing and development (EMD) work on the JSTARS business jet solution after the Pentagon in December approved the program to move into the next phase of the acquisition cycle.

However, senior Air Force and Defense Department acquisition leaders recently revised the acquisition strategy for JSTARS, delaying the expected contract award for the airframe by as much as six months.

JSTARS is still on track to achieve "Milestone B," an acquisition step that approves entry into the EMD phase, in the fourth quarter of fiscal year 2017, Defense News reported in February. But the EMD contract award has slipped to the first quarter of FY18.

Officials have cited radar integration work as one area of risk for the JSTARS recapitalization program.

The service may also postpone the deadline for declaring initial operating capability (IOC) for the program. The Air Force had planned to declare IOC for the JSTARS recap in fiscal year 2023, but on Feb. 19 service spokesman Maj. Rob Leese projected IOC would take place "in the mid-2020s."

"We will continue to update our projections as the JSTARS program progresses," Leese said.

Email: lseligman@defensenews.com

Twitter: @laraseligman