WASHINGTON (Reuters) - A Raytheon Co system built into big blimp-like balloons has demonstrated capabilities that could make it easier to detect and track certain enemy ballistic missiles, the company and the U.S. Army's manager of the program said.

System tests in December at White Sands Missile Range, New Mexico, successfully tracked four targets mimicking tactical ballistic missiles in "high-threat" regions, Raytheon is set to announce on Tuesday.

The hardware is known as Joint Land Attack Cruise Missile Defense Elevated Netted Sensor System, or JLENS. It includes a targeting radar and a wide-area surveillance radar with a 360-degree look-around capability that can reach out to 340 miles.

Each radar system flies as high as 10,000 feet with a separate, 74-meter-long aerostat capable of operating aloft for up to 30 days while tethered to mobile moorings.

The bulbous, blimp-like aerostats work in pairs officially estimated to cost about $450 million - though Raytheon has said it can lop a third off of that price.

The December 6-7 tests met all primary and secondary goals, including "launch point estimation, ballistic tracking and discrimination performance," Raytheon, the world's biggest missile-maker, said in a draft press release.

The missiles were tracked during their so-called boost phase, it said, including two that were "ripple-fired" one after the other.

JLENS' "proven capabilities" provide another tool that could help protect U.S. and partner forces from "the growing ballistic missile threat" and other threats, Dean Barten, who manages the program for the Army, said in the release. Barten's statement was confirmed to Reuters by an Army spokesman.

The army is preparing one of its two existing JLENS systems, formally known as an orbit, for a three-year exercise that will tie it into a high-tech shield designed to protect the Washington D.C. area from air attack. Continued...