v1.1.2 / chapter 2 of 3 / 01 mar 08 / greg goebel / public domain
* Although US missile defense programs have risen and fallen, at no time has the issue gone completely silent. In the 1990s, new missile defense programs were initiated, with one track pursuing "theater missile defense (TMD)", using improved air-defense missiles and advanced technologies such as high-powered lasers, and another, more controversial track pursuing "national ballistic missile defense (NMD)". This chapter describes TMD efforts, while the next describes NMD work.
* The reason for interest in TMD systems from the early 1990s was Saddam Hussein's use of Scud TBMs in the Gulf War, and the seemingly impressive ability of American Patriot missile to hit the Scuds. However, though during the war the US Army claimed "100% effectiveness" in intercepting Scud missiles, their own postwar analysis cut their claims in half. A team of researchers from the Massachusetts Institute of Technology (MIT) challenged even these results, claiming that analysis of video footage of the intercepts showed no evidence that the Patriots had managed to hit even one Scud. As is typical of missile defense politics, the debate was long and often hot.
Whatever the case, the Gulf War demonstrated the threat of TBMs missiles to the US military and the ineffectualness of existing defense systems. Even Patriot advocates admitted that the missile was originally designed to shoot down aircraft, not missiles, and had been enhanced to provide only a limited anti-missile capability, mostly through a series of software changes.
The Patriot variant used in the Gulf War is designated the "Patriot Advanced Capability 2 (PAC-2)". It is 5.2 meters (17 feet 1 inch) long, has four tailfins with a span of 87 centimeters (2 feet 10 inches), weighs 914 kilograms (2,015 pounds), and has a range of at least 70 kilometers (43 miles). The PAC-2 is carried and launched from a trailer, known as a "launch station (LS)", with the trailer towed by a "HEMMT" heavy field tractor-truck. Each launch station carries four missiles. A battery of Patriots, with up to 16 launch stations, also includes an "engagement control station (ECS)" trailer; a phased-array radar system ("RS") trailer; and other elements for power generation and command, control, and communications.
The Patriot PAC-2 uses a proximity-fuzed warhead that detonates when it comes near the target. In use against Scuds, the Patriots generally seemed to have just thumped a missile that was falling out of the sky anyway. In 1992, after the Gulf War, minor changes were instituted in a "Quick Response Program (QRP)" to improve the guidance and launch systems for greater effectiveness.
* The threat of TBMs and the limitations of the Patriot has led the US military to investigate TMD systems to protect combat forces in a war zone, with the design effort mostly under the umbrella of the BMDO.
The US Army has developed a refinement of the venerable Hawk anti-aircraft missile to provide a limited defensive TMD capability, but the main focus is on a new version of the Patriot, designated "PAC-3", that was designed from the outset to attack missiles with an HTK vehicle. PAC-3 is currently being phased into service in the form of software, guidance, and system upgrades to the existing PAC-2 systems, but the ultimate goal of these changes is support for the new PAC-3 missile.
The Lockheed Martin PAC-3 missile is an updated version of the Lockheed Vought "Extended-Range Interceptor (ERINT)" missile, which scored hits on missile targets in tests in 1993 and 1994. PAC-3 is a slightly stretched of ERINT with an improved guidance system, and has proven accurate in recent intercept tests. The PAC-3 is 5.2 meters (17 feet 1 inch) long, has a diameter of 25 centimeters (10 inches), has a tailfin system with a span of 48 centimeters (1 foot 7 inches), weighs 318 kilograms (701 pounds), and has a range of 20 kilometers (12.4 miles). The tailfin system, consisting of a set of cruciform fixed fins followed by maneuvering fins, is used for coarse flight control, while the forward section of the fuselage is ringed with 180 small solid-fuel thrusters for agile maneuvering.
The PAC-3 is fired from the same launch station as the PAC-2, though a launch station can accommodate 16 PAC-3s in contrast to 4 PAC-2s. The PAC-3's warhead can optionally release 24 steel slugs to increase kill probability when engaging an aircraft or cruise missile.
The PAC-3 is equipped with a millimeter-wave radar seeker linked to a processor that not only computes the interceptor's trajectory, but also matches the incoming warhead with a library of known warhead types to determine the optimum attack technique. Although the PAC-3 has its own guidance system, it has an RF data link to maintain contact with the launch control center.
The Army is also emphasizing the usefulness of PAC-3 for cruise missile defense, and Lockheed Martin performed test intercepts of cruise missile targets at the White Sands Missile Range, New Mexico, in mid-2000. While cruise missiles are much slower targets than a TBM, they are generally stealthy and fly low to the ground. Developing a seeker system that can pick such a target out of the "ground clutter" is tricky.
Lockheed Martin completed development tests of the PAC-3 in late 2001, having performed 12 successful tests in 12 shots, and the Army took over evaluation testing at that time. A decision was made to deploy the PAC-3 in early 2003, with 55 in service at the start of the Anglo-American invasion of Iraq in the spring of 2003, during which a number of PAC-3s were fired. PAC-3s have also been deployed to South Korea to defend the country against North Korean TBMs.
The US Army is now working on an improved version of the PAC-3 under the "Missile Segment Enhancement Program (MSEP)". The primary improvement will be a larger solid-rocket motor that will double the range against air-breathing threats and improve range by 50% against TBMs. It will have larger fins and a datalink system to provide data on engagement results. All PAC-3s are expected to be brought up to MSEP standard from 2008.
* The Netherlands and Germany are obtaining the PAC-3, and the PAC-3 is being used as the centerpiece in a collaborative program between the US, Italy, and Germany designated the "Medium-Extended Air Defense System (MEADS)". MEADS is essentially a next-generation follow-on to existing Hawk and Patriot SAM systems, focused on developing a mobile tactical launch and control system built around the PAC-3 that will be more capable, reliable, and easily transported than the current Patriot system. Work on MEADS is being conducted by a consortium of Lockheed Martin, Alenia Marconi Systems, and EADS.
MEADS will be able to deal with a range of airborne threats, including manned aircraft and tactical missiles. It features a truck-mounted vertical launcher that carries eight PAC-3s; the launcher was originally supposed to carry 12 missiles but this proved unnecessary, particularly because the launcher can be reloaded in minutes. Each MEADS battery will feature a "Surveillance Radar (SR)" unit, operating in the UHF band to provide good search capabilities, and two "Missile Fire Control Radar (MFCR)" units, operating in the microwave X band to provide good targeting capabilities. Each radar will be carried on a truck.
The program was begun in the mid-1990s. The US is providing 58% of the funding, while Germany is providing 25% and Italy 17%. A system demonstration was performed in 2004, with formal go-ahead for the program given in 2005. Current schedule envisions MEADS going into service in 2014.
* The Patriot PAC-3 is intended as a last-ditch "lower tier" defense against incoming missiles at an altitude of 20 kilometers (12.5 miles) or less. The US Army also is pursuing a "Theater High Altitude Air Defense (THAAD)" system as an "upper tier" defense to hit incoming missiles at higher altitudes, from 40 to 100 kilometers (25 to 62 miles). The finless, spike-like, 6.2 meter (12 feet 4 inches) long THAAD follows a similar but much cruder system named ERIS that was tested in the early 1990s, which was test fired twice and failed both times. ERIS was not an operational system in any case, with a kill vehicle that weighed hundreds of kilograms and a seeker that took a half hour to cool to operational temperature.
THAAD's kill vehicle, in contrast, weighs tens of kilograms and cools down immediately after launch. As currently envisioned, a THAAD defense systems is alerted to an incoming missile by orbiting satellites with infrared sensors. Once the incoming missile comes within range, the interceptors use ground-control radars to lock onto the target. THAAD's ground-control radar is a high-frequency X-band system that operates above 10 gigahertz to provide a detailed image of the target.
THAAD interceptors are fired from launchers carried on trucks, and guided to the vicinity of the target by the satellites and the X-band radar. Once the interceptor reaches an altitude of about 40 kilometers (25 miles), the booster portion of the missile falls away, with the hit-to-kill vehicle continuing on an intercept course.
The kill vehicle is controlled by thrusters around its center of mass. When it reaches a certain range from the target, the kill vehicle opens a seeker head with a gimballed 256 x 256 element infrared imaging array. The seeker can identify the warm target against the cold background of space, and its processor uses the image to direct a collision course optimized for the type of target. THAAD uses an infrared seeker because it attacks targets above the weather, while the lower-altitude PAC-3 uses a millimeter-wave radar to locate targets in clouds.
One or two THAADs would be fired to try to destroy the target at high altitude, and if they failed, several PAC-3s would be fired to destroy it at closer range. BMDO officials do not claim they can kill a single incoming warhead with a single missile, stating that "you need more than one shot to do it."
* That's the plan. In reality, while PAC-3 tests have gone well, tests of THAAD have proven troublesome. The first six THAAD tests all failed, and an investigative panel appointed by the BMDO concluded that intense political pressure on the project was leading to shoddy engineering practices and recommended corrective action. The seventh test, on 10 June 1999, was successful, scoring a direct hit on a Hera target vehicle, much to the relief of the program's advocates.
The program was not axed, but funding was cut, and the engineers had to go back to the drawing board. Another setback to the program took place in 2003, when two explosions took place at the Pratt & Whitney plant that built THAAD's solid-fuel rocket engine. The explosions were not caused by the THAAD boosters, but the facility was badly damaged and production of the rocket engines was affected. Program officials had to find an alternate source for the engines.
A new sequence of flight tests of the revised THAAD, claimed to be "90% different" from the original, began in late 2005, with the initial shot in the series on 22 November proclaimed a success, though it was strictly a systems evaluation flight, with no target launched for intercept. Of course program officials are hoping things will work much better this time around. If things remain on track, THAAD is expected to go into service in 2009.
* An issue with THAAD is that it encourages visions of an NMD system. Since a TMD system is intended to protect a battle area, there is no reason exactly the same system cannot be used to protect a small country. In fact, Israel and the US are collaborating on an upper-tier interceptor missile named "Arrow", which could possibly be used together with the PAC-3 to defend Israel from ballistic missiles.
The first Arrow battery was deployed in the spring of 2000. It appears to be a two-stage missile with capabilities intermediate between the Gulf War Patriot PAC-2 and THAAD, with longer range than the Patriot but a proximity fuze warhead instead of an HTK vehicle. However, in a number of tests against TBM targets, the Arrow actually performed a direct hit much more often than not.
The Arrow is launched from a trailer-mounted canister, with six canisters per trailer, and works in conjunction with a "Green Pine" X-band radar system, which not only targets the incoming ballistic missile, but also identifies the missile's launch coordinates for a rapid counterstrike against the mobile missile launcher. The primary threats the Arrow is designed to counter are Syrian Scud-D TBMs and the Iranian Shahab IRBM.
Israel originally intended to set up three separate Arrow batteries, but decided later to consolidate and place all the command and control assets in a single defense center, though missile launchers are distributed in various locations. Officials say that the idea of setting up separate batteries ran into troubles with coordination between the three sites, but cost may have played a role as well.
An "Arrow 2" is now being developed under the "Arrow System Improvement Program (ASIP)" to ensure that the Arrow system keeps up with improvements in the ballistic missile technology of potential adversaries, as well as to improve the ability of the Israeli military to perform counterstrikes on mobile launchers. First Arrow 2 test launch was in late 2005. The US has been heavily involved in Arrow funding and development, with Boeing setting up a stateside production line to build elements for assembly in Israel and also cooperating on the Arrow 2 / ASIP.
Faced with more capable Iranian ballistic missiles, the Israelis are now considering an exoatmospheric system with a much wider engagement umbrella. A new interceptor would be built for the system, though it might retain the original Green Pine radar system, with upgrades.
* A group of European countries has been working on an air defense system based on the "Aster" surface to air missile (SAM), built by EuroSAM, a collaboration of the Anglo-French Matra BAe Dynamics Aerospace (MBDA) company, the French Thales (previously Thomson-CSF) company, and the Italian Finmeccanica / Alenia company. The Aster will be used as both a naval and a mobile ground-based SAM, and is being obtained by the armed forces of France, Italy, and Britain.
The initial Aster variants are the "Aster 15" and the "Aster 30". They are two-stage weapons, which differ only in the size of the solid-fuel booster. The short-range Aster 15 has a launch weight of 310 kilograms (684 pounds), a length of 4.2 meters (13 feet 9 inches), and has a range of 30 kilometers (18.6 miles); while the long-range Aster 30 has a launch weight of 450 kilograms (992 pounds), a length of 4.9 meters (16 feet 1 inch), and range of 120 kilometers (75 miles).
The Aster uses an inertial guidance system during most of its flight, with course corrections provided by the sea- or ground-based radar control system over a datalink, but uses an a fully active guidance system for terminal attack. It has a directed fragmentation warhead with a proximity fuze system; the warhead can break up into small fragments for soft targets or large fragments for hard targets. Although the missile is winged, it does use thrusters for high-speed terminal maneuvering, and can perform HTK intercepts.
There are two naval systems, the "Surface to Air Anti-Missile (SAAM)" system that uses the Aster 15 for defense against sea-skimming antiship missiles; and the "Principal Anti-Air Missile System (PAAMS)", which uses the Aster 15 and Aster 30 for defense against the wider range of airborne threats. The missiles are fired from vertical-launch silos on board the launch vessels, and are directed by a control system featuring a multimode phased array radar. French vessels will use the Arabel radar, while Italian vessels will use the Empar radar, and British vessels will use the Sampson radar.
The ground-based system is known as "SAMP/T", for "Sol-Air Moyenne Portee" or "Surface-to-Air Medium Mobile". It uses the Aster 30. SAMP/T features a mobile launcher with eight vertically-launched missiles and a fire control system based on the Arabel multimode phased array radar. The system is designed to be airlifted in standard military transports.
The initial Block 1 Aster 30 also has a limited TMD capability, but a "Block 2" system is now in discussion that will be much more capable, with an enlarged and improved upper stage and seeker system, giving an expanded engagement envelope. Work is underway for a satellite missile warning and tracking system to cue the missile, as well as for an advanced radar to provide missile guidance. The Block 2 Aster is expected to go into service in 2012. The European EADS organization has also been publicizing a concept for a high-altitude interceptor missile named "Exoguard", though details remain unclear.
European governments are very careful to refer only to development of a TMD capability to protect deployed forces, since talk of an NMD defense system is politically controversial. The emphasis is on developing an air-defense system that can take on TBMs as part of its brief, this being a cheaper approach than trying to develop a dedicated TMD system, and much easier to sell to the public.
* The US Navy has been working on their own TMD system. The original effort included both a lower tier "Navy Area Wide (NAW)" interceptor and an upper tier "Navy Theater Wide (NTW)" interceptor, both based on the Navy's existing "Standard SM-2" SAM. NAW was to be based on a "Block 4A" variant of the SM-2. This was to add a fast-burn "Mark 74" booster stage to the missile; an infrared seeker mounted on the side of the nose; a modified proximity fuzing system; and a modified warhead to produce bigger fragments for improved kill probability.
Although some initial tests went well, NAW simply proved too costly, and the Navy abandoned it in December 2001. In early 2003, the Navy awarded a contract to Raytheon to develop a simplified version of the NAW under the "Extended Range Active Missile (ERAM)" program, but this weapon was only intended for long-range defense against aircraft, not for lower-tier missile defense. Raytheon was awarded the contract without a competition, since the Navy wanted to field ERAM by 2010 and Raytheon had most of the pieces already in place.
ERAM will use the SM-2 Block 4A airframe and warhead, coupled to an active radar seeker derived from that used on the AIM-120 AMRAAM air-to-air missile. Existing Standard missiles use "semi-active" radar homing, which requires that the target be illuminated by shipboard radar. ERAM's active radar seeker will be autonomous, and allow attacks on targets over the horizon. The Navy may try to see if ERAM can still perform attacks on ballistic missiles. Current schedule for ERAM is unclear.
* NTW also is based on an SM-2 with a fast-burn booster stage, but adds an HTK vehicle, known as the "Lightweight Endo-Atmospheric Projectile (LEAP)". The result is designated "SM-3". The first successful SM-3 test took place on 25 January 2001, with the missile launched from the AEGIS cruiser USS LAKE ERIE in the Pacific near Hawaii. The LAKE ERIE used its S-band SPY-1B phased-array radar to perform tracking.
The SM-3 did not carry a fully functional LEAP in this test, but it successfully closed to within the required distance to the target and the LEAP acquired the target with its seeker sensor. A year later, on the fourth test on 25 January 2002, another SM-3 fired by the LAKE ERIE scored a kill on an Aries ballistic missile target, hitting at a relative speed of four kilometers per second. This success was followed by another intercept in June 2002, and a third success on 21 November 2002, with the third intercept shooting down the target during boost phase. The next attempt was a failure, but following tests proved generally successful.
A decision was made in early 2003 to field the SM-3. A total of 16 Aegis cruisers and destroyers had been upgraded to the "initial defensive operations (IDO)" configuration by the beginning of 2008, though nine of them only had tracking capability and could not handle the SM-3 interceptor. Ultimately, all existing Aegis cruisers and destroyers could be upgraded, as well as vessels currently in the procurement pipeline.
The upgrade involves fit of an improved Aegis radar, the "SPY-1E". The SPY-1E has greater power, range, and target discrimination than its predecessor. A next-generation X-band radar is in the development pipeline behind the SPY-1E. NTW's planned operation from cruisers and destroyers does give it an advantage, since such vessels can be sent to remote trouble spots as part of a normal naval deployment, lowering the profile of the introduction of missile defense weapons in such regions during a crisis. Work is underway on development of a "Block 2" NTW system. The Block 1 LEAP has an infrared seeker that operates at a single IR wavelength, while the Block 2 seeker operates on two wavelengths and has active radar sensing as well.
On 20 February 2008, an SM-3 fired from the LAKE ERIE from off of the Hawaiian actually intercepted a satellite. The satellite was a classified spacecraft, designated "NROL-21", that had failed in orbit after being launched in December 2006. It was falling to Earth anyway, with the rationale for the interception merely to ensure that it was broken up thoroughly so it wouldn't present a hazard when it came down. The interception was loudly criticized by Russia and China, with the Russians claiming that it was actually an attempt to demonstrate an antisatellite weapon system.
* Japan is cooperating with the US on the NTW program, formally initiating a program in late 2003 to obtain a missile-defense system, based the Patriot PAC-3. 124 PAC-3s will be obtained by 2010, with 32 provided by the US and the rest license-built by Mitsubishi Heavy Industries. The Japanese are deploying a new, indigenously-designed radar system, the FPS-XX, at four sites to prove missile tracking capabilities, working jointly with US X-band radars. The Japanese Maritime Self-Defense Force (JMSDF) is also acquiring the SM-3 for JMSDF Aegis-class vessels, with their radars upgraded accordingly. The first test launch of an SM-3 from a JMSDF vessel was in late 2007, with the SM-3 kill vehicle hitting a target vehicle simulating a North Korean ballistic missile. The political message behind the test was blatantly obvious.
South Korea has considered a ballistic missile defense, and the possibility that a TMD system could be based in Taiwan has brought protests from the government of mainland China. The mainland Chinese have been upset about American missile-defense efforts, even though China was not a signatory to the ABMT. The country relies heavily on ballistic missiles as a military capability, and an effective missile defense against their relatively small and crude arsenal of long-range strategic weapons could leave them vulnerable to attack.
* The Navy is considering a follow-on version of the SM-3 that would increase range by expanding the diameter of the second stage from 35 to 53 centimeters, matching the width of the fast-burn booster.
The service has also considered next-generation technology for TMD. One concept is for a "Mass Moment Missile (3M)", which would achieve directional control by shifting a mass around inside its airframe, instead of thrust vector controls. The result would be a lighter and faster missile. Improved seeker technology is another item being investigated. One option is a simplified, cheaper passive infrared seeker that would have a 220 degree field of view, using a panoramic mirror to reflect infrared energy onto a fixed detector. An alternative option is an advanced active seeker, probably using millimeter-wave radar technology.
* All the weapons described so far in this chapter are designed to hit an incoming missile. In some ways, this is the phase of the attack when the defense is most difficult, since the threat is moving at high speed; it has lost much of its mass and is unpowered, reducing its targeting profile; it may have deployed decoys or other countermeasures; and even if it is hit, it will likely fall on defended territory, which may be particularly troublesome if it is carrying a chemical or biological warhead.
One of the ways to get around these difficulties is during the "boost phase" of the missile, just after it has been launched and is climbing out of the atmosphere. During boost phase, the threat is moving relatively slowly; is a hot and bright target; is unprotected by countermeasures; and if it is hit, it falls back into the launch area.
In the early 1990s, BMDO developed a number of "unmanned aerial vehicles (UAVs)" for boost-phase intercept (BPI) of TBMs. These were drone aircraft that could fly at high altitudes for extended periods of time near a battle zone to target TBM launches and hit them with "hypervelocity" missiles as they were climbing. The UAVs never got out of the prototype stage, with the program being cancelled and the UAV prototypes passed on to the US National Aeronautics & Space Administration (NASA) for a high-altitude flight research program.
The Israelis were also interested in the concept. In the mid-1990s, a consortium of the Israeli companies IAI, Rafael, and Wales attempted to design a UAV to carry high-speed interceptor missiles for BPI. The result was the planned "HA-10 UAV", which would have carried two or three interceptor missiles derived from the Rafael Python air-to-air missile. However, BPI turned out to be far too technically challenging, and the HA-10 project was abandoned.
The Israelis still feel that UAVs can be used effectively against TBMs, but they feel that their mission should be to locate TBM sites and attack them with cruise missiles before they can launch, a task which is perceived as easier than BPI, and which would also be useful for dealing with other ground targets from far away. This scheme has been given the name "boost phase launcher intercept (BPLI)". Missile intercept would be performed by "terminal defense" systems such as the Israel Arrow anti-missile and the THEL laser system, discussed below.
* In late 2003, the US did commit to the development of a ground-based BPI system, the "kinetic energy interceptor (KEI)", to be developed by a team of Northrop Grumman, Raytheon, and Orbital Sciences Corporation. The program is focused on development of a multistage interceptor with an HTK vehicle, with targeting provided by space-based, airborne, or other sensing platforms, and terminal guidance provided by a imaging infrared system.
Northrop Grumman is building the launcher system, Raytheon is building the kill vehicle, and Orbital is building the booster. The booster is 11 meters (36 feet) long and 91 centimeters (36 inches) in diameter. The KEI will be two to three times faster than THAAD or NTW, and will be fired from a twin-tube mobile launcher that can be airlifted to a battle theater on a C-17 cargolift aircraft. Initial test firings are expected in 2009, with initial operational deployment as early as 2010. A sea-based variant would be deployed a few years after that.
* Well before the US formally began development of a ground-based BPI system, the USAF had begun work on an "Airborne Laser (ABL)" BPI system, which will consist of a modified Boeing 747 jetliner firing a "chemical oxygen-iodine laser (COIL)" weapon through a nose turret. The production system will have the designation "Attack Laser 1A (AL-1A)".
The ABL follows an Air Force test program conducted in the early 1980s with the "Airborne Laser Laboratory (ALL)". The ALL was based on a Boeing KC-135 cargo-tanker aircraft and fitted with a laser behind the cockpit. The ALL scored five "kills" against Sidewinder air-to-air missiles and a Firebee target drone, but it was a purely experimental system, with neither the range nor power of a useful operational system.
The ABL is a big step beyond the ALL. While the short Boeing 747-200 jetliner was originally considered as the ABL platform, the need to provide self-defense capabilities pushed the USAF towards the larger 747-400, which has a greater payload capacity and very long range and endurance. In early 2000, a new-build Boeing 747-400F air freighter for the ABL system was delivered to Boeing facilities in Wichita, Kansas, where it received structural reinforcement and was fitted with a nose turret.
The "YAL-1A", as the prototype ABL aircraft is designated, performed its first flight with the airframe modifications on 18 July 2002, with the first attempt to fire up the COIL (in a ground test rig) in November 2004. The COIL is powered by a chemical reaction between two fuels that creates energized oxygen, which then emits light that builds up in an optical cavity and emerges as a focused, coherent laser beam. The COIL will be directed by a 2-meter-wide focus mirror.
Initial targeting of a missile will be by an "infrared search and track (IRST)" sensor system derived from that used on the F-14 Tomcat fighter, followed by precise targeting with a small 10-kilowatt laser. The laser in the precise targeting system not only performs rangefinding, but its reflected beam is also analyzed to observe air turbulence between the aircraft and the target. This turbulence information is used to control an "adaptive optics" system that adjusts a matrix of precision pistons attached to the back of the COIL focus mirror, modifying the shape of the mirror slightly to keep the beam intensity on the target constant even in the presence of atmospheric turbulence.
The Air Force has planned a fleet of seven AL-1As. The program has proven more difficult than expected, with cost increases and schedule slippage -- not too surprising for such an ambitious effort. Currently, the first attempt to intercept a ballistic missile is scheduled for 2008 at earliest, five years later than originally scheduled. At present, there isn't a good estimate of when the ABL will be fielded.
In a combat scenario, five AL-1As would be sent to a war zone, and two AL-1As would be on station in the air at all times. The two aircraft would be able to engage 5 to 10 missiles simultaneously. They would fly above the clouds at an altitude of about 12.2 kilometers (40,000 feet), cruising at a range of about 90 kilometers (56 miles) outside of hostile territory. Each aircraft would be able to stay on station for 12 hours, but inflight refueling could be used to extend their endurance. Boeing is now considering use of relay mirror systems to extend the ABL's range. Such mirror systems could be carried by a high-flying airship, or placed in orbit.
The COIL's beam will be about 38 centimeters (15 inches) wide. It would be blocked by cloud cover or even thick atmosphere, making it ineffective against cruise missiles or manned aircraft at long range, but once the target missile rises above the atmosphere, the laser could target it at a maximum range of from 290 to 580 kilometers (180 to 360 miles). The target will be destroyed by a laser burst three to five seconds long. Each AL-1A would carry enough hydrogen peroxide fuel for about 20 laser shots. The YAL-1A prototype will not be fitted with a full system, at least initially, and will not have the range of an operational system.
Some laser weapon advocates have suggested that AL-1A could also destroy low-orbiting satellites, but this is politically controversial and project officials have downplayed it. The AL-1A will also be able to pinpoint the launch point of missile targets, and relay those coordinates to strike aircraft or missile launch platforms to permit a counterstrike against mobile launchers.
* Critics have taken shots at laser defense systems, saying that solid-fuel missiles would boost too fast and be too robust a target to destroy with a laser beam. The critics also say that simple countermeasures, such as spinning the missile or covering it with a layer of cork, would provide protection against a laser beam. The MDA replies that though it is possible to pick at any one element of a missile-defense scheme, the system being envisioned has multiple layers -- none of which are necessarily expected to be perfectly adequate in itself, but which taken together present an obstacle course to anyone trying to launch an attack with a long-range missile.
* Laser systems are also being developed to intercept small battlefield missiles and to protect naval vessels from antiship missiles. In June 2000, one such system, the "Tactical High-Energy Laser / Advanced Concepts Technology Demonstrator (THEL/ACTD)", destroyed a Russian-built "Katyusha" 122 millimeter unguided rocket in flight during a test at White Sands Missile Range in New Mexico. This was regarded as an impressive accomplishment, since the Katyusha is a very small and fast target.
The THEL program was begun in 1996, with development by a team headed by TRW and funded cooperatively by the US Army and Israel. The Israelis wanted to use THEL to defend their borders from rocket attacks. THEL was based on a chemical deuterium-fluoride laser and included an L-band radar system provided by Elbit. THEL was basically a fixed-site defense, implemented as several cargo-container sized structures placed on concrete pads.
THEL validated the technology but a fixed-site defense wasn't all that useful, and so the Army and the Israelis went on to a "Mobile THEL (MTHEL)" effort, with initial tests performed in the spring of 2004. The production MTHEL system was to consist of three trucks, one for the laser, one for fuel, and one for radar and control. All three could be carried on a single Lockheed Martin C-130 Hercules transport. However, the Israelis were confronted with new rocket threats, including the Iranian-made 240 millimeter "Fajr 3" rocket, with a range of 43 kilometers, and the 330 millimeter "Fajr 5" rocket, with a range of 70 kilometers. Fajr 5 could threaten much of northern Israel. MTHEL was seen as inadequate and cancelled in 2005.
Boeing has worked on a small COIL system called the "Airborne Tactical Laser (ATL)", a short-range system that would be small enough to fit on the MV-22 Osprey tiltrotor, or a large helicopter or other aircraft. ATL is intended for missions such as interception of antiship cruise missiles, or escort of special operations forces. Initial demonstrations of the ATL on a C-130 Hercules took place in 2007.
* The US military and defense industry remain very interested in tactical lasers, with the Army, Air Force, and Navy running a joint program office. The core effort is the development of a "High-Power Solid-State Laser (HPSSL)". Raytheon has done work on a compact HPSSL, intended to be used over the long run with aircraft such as the Lockheed Martin F-35 Joint Strike Fighter, the B-1 or B-2 bombers, the AC-130 gunship, or unmanned aerial vehicles. There is a short-takeoff version of the F-35 that has a lift fan driven by a shaft from the aircraft's engine, and Lockheed Martin has envisioned pulling out the lift fan and installing an HPSSL along with a power generator driven by the shaft.
The US Army has worked on a demonstration program with Lawrence Livermore National Laboratory (LLNL) and industry partners to mount an HPSSL on a hybrid gas-electric version of the HUMVEE, the well-known Army "Hummer" four-wheel truck. It could be used to intercept battlefield rockets, artillery shells, and eventually UAVs and TMDs. It would also be used to detonate land mines. A Hummer equipped with an HPSSL and targeting gear is regarded as a very attractive weapon system, not only mobile on the ground but easily transported by cargolift aircraft or by heavy-lift helicopter, and ready to go into combat on arrival.
LLNL demonstrated a 13 kilowatt refrigerator-sized flashlamp-based HPSSL system in 2002, which managed to burn a one-centimeter (0.4 inch) wide hole in a two centimeter (0.8 inch) thick steel plate in six seconds. This was impressive for an HPSSL, but an operational HPSSL will need to produce 100 kilowatts. A production HPSSL will be pumped by light-emitting diode arrays. Such arrays will produce a great deal of heat and so cooling systems will have to be developed to permit acceptable firing rates. One scheme envisions rotating chilled crystalline slabs into the laser mechanism with each shot. Each shot would use about a liter (about a quarter a US gallon) of fuel. A solid-state laser with the capability to destroy a main battle tank is not expected until well after 2010.
The Israelis are very interested in solid-state lasers, finding them more practical than chemical laser systems like MTHEL. Over the short term, however, Rafael of Israel is working on a program designated IRON DOME to develop short-range interceptors to destroy artillery shells and short-range rockets. IRON DOME will consist of a radar and control system linked to a battery of "Tamir" interceptors, which will be an HTK weapon, though with a backup proximity fuze system. The Tamir has a boost-sustain rocket motor that keeps it under continuous thrust to impact, with midcourse corrections provided over datalink.
Critics claim that the Tamir interceptors will be far more expensive than the threats they are intended to neutralize, but the Israeli government feels that the program would be worth its cost just in terms of getting out of the ugly circle of reprisals and escalations every time a rocket from Gaza lands in an Israeli neighborhood. It would make things much simpler politically if the rockets were simply blown out of the sky every time they were launched. In the meantime, research on solid-state lasers is continuing under a project codenamed DAVID'S SLING.
