February 25, 2012:
After two decades of debating the matter NATO has finally agreed to buy five RQ-4 Global Hawk UAVs for reconnaissance work in operations like the Libyan campaign last year. NATO will get the Block 40 model, which became operational two years ago and has MP-RTIP AESA radar. This sensor does the same job as the E-8 JSTARS ground radar aircraft AESA but is built to be mounted in the RQ-4. An updated AESA (Active Electronically Scanned Array) radar for JSTARS enables this UAV to spot smaller, man sized objects.
AESA type radars have been around a long time, popular mainly for their ability to deal with lots of targets simultaneously and produce a more accurate picture of what is out there. AESA radar consists of thousands of tiny radars that can be independently aimed in different directions. An AESA radar made the JSTARS aircraft possible, as it enabled it to locate vehicles moving on the ground. The smaller MP-RTIP radar for the RQ-4 can also spot smaller objects on the ground.
NATO will use their AESA equipped RQ-4s to monitor large battle areas, tracking the location and movement of vehicles. Two decades ago, when acquiring such recon aircraft was first proposed, it was believed they would be manned aircraft like the JSTARS (which had done so well in Kuwait in 1991) but as time went on UAV technology gradually made manned aircraft too expensive to buy and operate.