Raytheon and Northrop Grumman secured contracts from the U.S. Air Force to conduct risk-reduction activities for the radar subsystem of the new Joint Surveillance Target Attack Radar System (JStars). The sole-source awards require the contractors to mature their competing radar designs by Sept. 30, 2017.

On March 24, the Department of Defense announced a $70.2 million award to Northrop Grumman in Baltimore, and a $60 million award to Raytheon Space and Airborne Systems in McKinney, Texas, both to provide nonrecurring hardware and software engineering “to ensure radars are scaled” to meet the JStars recapitalization program requirements.

The radar subsystem, a component of the JStars recapitalization program, is being developed to succeed the existing AN/APY-7 side-looking phased array radar housed in a radome beneath the forward fuselage of the E-8C JStars aircraft, a modified Boeing 707-300. Three industry teams are contending to supply the new JStars host platform: Northrop Grumman with a system based on the Gulfstream G550 business jet; Lockheed Martin on the Bombardier Global business jet; and Boeing on the 737-700.

The APY-7 is a passive electronically scanned array (PESA) radar, which has a central radio frequency source; the new radar will be an active electronically scanned array (AESA) radar. “By eliminating the PESA’s complex power distribution network, AESAs reduce signal loss and increase radar sensitivity,” the Air Force says. “Both characteristics enhance detection capability and reduce the effects of a smaller aperture. Also, AESA radars allow for digital beam forming, which enables a number of advanced signal processing techniques.”

Raytheon has said its proposal is based on the APS-154 Advanced Aerial Sensor, an AESA radar it has developed for the U.S. Navy’s P-8A Poseidon maritime patrol aircraft. Northrop Grumman has not revealed details of its proposal.

The JStars recapitalization program is currently in the risk reduction and technology maturation phase of the Department of Defense acquisition cycle, having received “Milestone A” approval from the undersecretary of defense for acquisition, technology and logistics on December 10. In budget documents released in February, the Air Force said it expects to obtain a Milestone B decision to move into the engineering and manufacturing development (EMD) phase in the fourth quarter of Fiscal Year 2017, or in late summer 2017. The service plans to make an EMD contract award by the end of next year.

The EMD schedule has slipped by a year from previous plans. “The program’s had some struggles and we’ve extended the risk reduction phase of the program basically to lower overall risk,” Carolyn Gleason, Air Force deputy for budget, told reporters on February 9. “It delays EMD roughly a year, and we’re going to get the program back on track.”

The Air Force plans to field 16 operational JStars recapitalization aircraft, and to maintain one as a test aircraft. It plans to declare initial operational capability with four aircraft in the mid-2020s, with full operational capability set for Fiscal Year 2028.