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Last updated Sept. 13, 2002
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The concept of using unmanned aerial vehicles (UAVs) to counter ballistic missiles during their boost phase has been floated by the Israelis for the past five years or so. Until recently, the United States was more interested in using other platforms for that mission, prompting Israel to switch its sights to using UAVs to take out launch vehicles on the ground instead.
However, the popularity of UAVs in Afghanistan has brought this issue back into the U.S. funding debate over missile defense: in the House Armed Services Committee's report accompanying the fiscal year 2003 (FY 03) defense authorization bill in May 2002, the committee notes that given "the recent successes with armed unmanned aerial vehicles in Operation Enduring Freedom, [the Pentagon's Missile Defense Agency] may have overlooked the most promising near-term alternative for boost-phase defense - air-based kinetic energy boost-phase intercept. The committee urges MDA to give serious consideration to this option."
Originally, Israel was pushing for a UAV that could intercept missiles during their boost phases. The Israelis developed the HA-10, a stealthy, long-endurance UAV. They were able to make it several orders of magnitude stealthier than the U.S. Global Hawk's signature, but it was not quite stealthy enough (a spray-on stealth coating was created that could give a 5-10 decibels. reduction in radar reflectivity in the 5-10 gigahertz frequency range, but they needed one that would give a 15-25 decibels reduction). The HA-10 would carry two to three missiles dubbed the "MOAB" that would be based on the Python 4 and Python 5 missiles, but with larger warheads, infrared sensors and millimeter wave radar. The HA-10 was never built, as Israeli officials determined that, without American help, it was too technologically complex to be monetarily feasible.
During the late 1990's, the then-named Ballistic Missile Defense Organization (BMDO) at the Pentagon was somewhat open to the possibility of using UAVs for boost-phase intercept. It was thought that perhaps the Global Hawk could be armed with kinetic energy weapons, allowing it to intercept ballistic missiles during their first minute or so of flight. In 1996, A near-term system proposed by the Army and Lawrence Livermore National Labs employees envisioned it to be comprised of a Global Hawk UAV with three to six missiles; a new kill vehicle (light and simple enough not to weigh down the UAV); lightweight sensors (for the same reason); a countermeasures system for the UAV's self-defense; and a communication system. In 1996, it was thought that this system would have a 20-year life cycle cost of $4 billion and could reach initial operational capability by 2003. This plan proposed that up to 75 Global Hawks would suffice for a boost-phase intercept mission.
A concept definition study for UAVs with kinetic energy interceptors was given $10 million a year in FY 97 and FY 98. This was promoted as a backup to other airborne options for boost-phase intercept. As the Airborne Laser (ABL) progressed, BMDO lost interest in using UAVs for the same mission and dropped its support for them.
Israeli officials, realizing that they could not complete their HA-10 program without U.S. support, shifted their efforts toward developing UAVs that would hit missile launchers on the ground (i.e., act as Scud-hunters). This became known as boost-phase launcher intercept, or BPLI. Manned airplanes would not work for this mission, the Israelis believe, as they would have to loiter for long periods of time over hostile territory. The theory is that Israel could build a stealthy, high-altitude, long-endurance UAV based on the Heron that could search for Scud launchers. Once a Scud is launched, the UAV would try to destroy the launcher before it could hide — a time frame of approximately five minutes. The Heron is a long-endurance UAV that, at 32,000 feet, has a line of sight of "several hundred kilometers," according to Israel Aircraft Industries officials. It is powered by a Rotax 914 horsepower engine that would use a super charger to get to altitudes above 16,000 feet.
Now that the ABL program is struggling, and that UAVs have received so much attention for their work in Afghanistan, there has been some discussion of the Pentagon investigating using them for boost-phase intercept. However, there are some concerns in using the Global Hawk in this capacity. The UAV may become too expensive to use, thanks to mission creep. The technical challenge of getting a boost-phase interceptor that would be fast enough on a UAV might be extremely difficult to overcome, much less actually creating such a missile. And already there are complaints about the UAVs' imagery being difficult to use, so some upgrades would probably have to occur to its sensor package.
The last issue is a serious handicap to arming UAVs. A common complaint from battlefield commanders is that UAVs lack situational awareness and that because of this, using their imagery is like "looking through a big soda straw," according to Air Force Secretary James Roche. Targeting a fast-moving missile could be extremely difficult, especially if the UAV is going to have to see it and then catch it in the first minute or so of its flight. Then, there is the consideration about whether, if a UAV spies a missile being launched, it can determine within 90 seconds or so that it should launch an interceptor. The way the Global Hawk is configured now is that it takes imagery, which is then sent to a command and control center in Saudi Arabia, where it is dispersed out to analysts to examine. It is questionable that the chain could be shortened enough to make possible intercepting a missile during its boost phase.
A more realistic way of incorporating UAVs into missile defense is to use them for warhead detection and monitoring. One possibility is the proposed Airborne Infrared Surveillance system (AIRS), which would put an infrared sensor and data collection system on a Global Hawk with the hopes of tracking missiles during their midcourse segments. Support has increased for using UAVs for missile detection due to problems with the specified system for this mission, Space-Based Infrared System (SBIRS)-Low. The Senate Armed Services Committee urges MDA to "aggressively pursue this program" in its report for the FY 03 defense authorization bill — to the tune of $22 million. The committee cites the delay in SBIRS-Low's deployment and a dearth of systems capable of providing infrared signature data on missiles for its support of AIRS. AIRS would allow UAVs to fill a gap in surveillance but not force the development of a whole new sensor package or bring in the issue of weaponizing surveillance platforms (which would greatly constrict their flight paths).
The role of UAVs can be expanded in a beneficial way, but it is important to first examine what they currently can do and what enhancements would be needed to fulfill added requirements. A quick boost-phase intercept capability is not a reasonable expectation for the Global Hawk. Changes of that degree would elevate the cost of the UAV while presenting an arduous technical challenge. It would be much better to explore its abilities as a monitoring asset.
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