The advantage of the US Army's developmental JLENS - Joint Land Attack Cruise Missile Defense Elevated Netted Sensor - is that it is elevated. The surveillance and fire-control radars are hoisted aloft, up to 10,000ft, on twin tethered aerostats. From this vantage point, the radars can see a long way and look down into valleys that could otherwise conceal inbound cruise missiles from surface-based radars. Check out this Raytheon-produced video to see what I mean.
The disadvantage of JLENS is that the aerostats are tethered and the complete system is only as mobile as their mooring stations. But that could change. Addressing an IDGA military radar conference in Washington on May 7, JLENS product manager Lt. Col. Stephen Willhelm said there are plans for Block 2 and Block 3 versions of the system. Block 2 would use two untethered platforms, while Block 3 would mount both radars on one platform.
Block 3 could be like Darpa's ISIS (Integrated Sensor Is Structure) concept for a high-altitude, long-endurance airship with dual-band active radar arrays embedded in the envelope surface. But Block 2 could use hybrid airships - part airship, part aircraft - that would be easily repositioned to meet the threat. Lockheed Martin's Skunk Works revealed earlier this year it has talked to JLENS prime contractor Raytheon about using a derivative of its P-791 hybrid airship.
Willhelm says he is keeping his eyes on Block 2 and 3, but nothing is funded yet. Testing of the aerostat-based Block 1 system is to begin in 2010, with a second "orbit" to be available for operational deployment in 2011.