Overcoming recent test failures will be crucial to US ballistic missile defence plans

During the Gulf War in 1991, Patriot became a household name - a symbol of US determination to protect civilian populations as well as military forces from ballistic missile attack. Since then, the Patriot's capability against Scud-type missiles has been improved while work continues on a major upgrade and eventual replacement of the air-defence system.

Patriot's successors - the less resonantly named PAC-3, THAAD and MEADS - share one feature: interceptors that hit to kill, using the kinetic energy of body-to-body contact at high velocity to destroy the ballistic missile's warhead, whether conventional or nuclear, biological or chemical.

After a long run of successes, the recent string of failures during operational testing of the US Army's Patriot Advanced Capability 3 (PAC-3) upgrade may give defence planners pause for thought (see P18). The same PAC-3 missile is to be used in the Medium Extended Air Defence System (MEADS), and the same hypervelocity hit-to-kill missile technology is used in the Theater High Altitude Air Defense (THAAD) system.

Although Raytheon developed the original Patriot, Lockheed Martin in 1994 won the competition to develop the PAC-3 upgrade. The company is also developing THAAD, which will provide the upper layer - to PAC-3's lower layer - in a two-tier defence against short- and medium-range theatre ballistic missiles (TBMs). Lockheed Martin is also the US partner in multi-national development of MEADS, which is intended to replace PAC-3 within the two-tier TBM defence concept.

PAC-3 is spearheading the US shift to hit-to-kill interceptors for missile defence. In nine development tests between March 1999 and October last year, the upgraded Patriot intercepted five TBMs and missed only once. Operational testing has not gone so well. In four tests between February and May, three out of sevenPAC-3s failed to launch. Two intercepted and destroyed TBMs. One hit, but did not destroy, a Patriot acting as a missile target. And one missed a cruise missile because of an inaccurate cue from the ground.

The fact that two TBMs were each destroyed by a single PAC-3 in what were planned as two-missile ripple firings - the standard tactical engagement - will probably be viewed as adequate demonstration of the weapon's capability. But PAC-3's performance during operational testing could make it difficult for the US Army to win Department of Defense approval later this for full-rate production of the missile.

PAC-3 is in low-rate initial production and the first upgraded fire unit became operational in September last year with 16 missiles. But the US Army is struggling to fund plans to equip all Patriot battalions with a mix of PAC-3s and the latest PAC-2 version of the original Raytheon missile.

"The US Army will fight with a mix of missiles," says Mike Trotsky, Lockheed Martin Missiles & Fire Control vice-president, PAC-3 programme. "The fire-control logic is threat dependent: if it's a ballistic missile, it uses a PAC-3; if it's a fighter, bomber, helicopter or cruise missile, it uses a [blast/fragmentation] PAC-2."

The requirement calls for PAC-3 to be able to engage all targets, Trotsky says, a capability which will take on added importance when the missile is used in MEADS, which is intended to replace Patriot and defend against a wider spectrum of threats. As a result, the hit-to-kill missile does have an explosive fragmentation warhead - not for use against ballistic missiles, but to increase the kill radius when used against air-breathing targets.

Funding issue

Ensuring every Patriot battalion receives at least some PAC-3s will require 2,200 missiles, the US Army calculates. But only 1,130 are funded. As 16 PAC-3s replace four PAC-2s in a Patriot launcher, firepower will increase significantly, but cost is an issue, as PAC-3 is a more expensive missile than PAC-2. The objective is an average cost of $2 million, but Lockheed Martin's internal goal - and the "practical limit", says Trotsky - is $1.5 million.

Achieving that cost goal could be critical to the success of MEADS, which must be an affordable as well as capable replacement for Patriot. International sales would help, but Patriot operator Germany - which, together with the Netherlands, is viewed as an early export candidate - has deferred PAC-3 procurement in favour of MEADS development.

The US/German/Italian MEADS programme is in a risk-reduction phase necessitated by the decision to use the PAC-3 missile. Begun in July last year, the risk-reduction effort runs until April 2004, during which time the PAC-3 missile will be integrated into the MEADS architecture, system performance assessments updated and cost estimates produced, and prototype fire-unit elements demonstrated.

"The initial architecture was built around a new missile," says Joel Strickland, president of the MEADS International joint venture between Lockheed Martin, Alenia Marconi Systems, EADS and EADS/LFK. "In 1999 we decided to use PAC-3 to keep costs down," he says.

No major changes are required to accommodate PAC-3 because of MEADS' distributed and networked "plug and fight" architecture, says executive vice-president Klaus Riedel. This involves a core set of battle monitor software that allows for different combinations of fire-unit elements as well as different interfaces with national command and control systems. "We can plug whatever is appropriate into whatever is available," he says.

Whereas the full-up fire unit includes one surveillance radar, two multifunction fire-control radars, two operations centres and six 12-missile launchers - all truck-mounted and transportable by Lockheed Martin C-130 - a minimum engagement capability needs only one fire-control radar, one operations centre and one launcher.

"We are building an incredibly flexible architecture that can move with the forces, that will not degrade as elements engage and disengage, and that can take other assets into account," says Riedel.

Cost advantage

Operating and support costs are a major design driver. "The entire calling card is the life-cycle cost advantage this system offers. We provide more capability with fewer units, fewer people and fewer aircraft to carry them," says Strickland. The full-up fire unit requires only 19 soldiers, but has 72 missiles ready to fire in six launchers compared with 32 for Patriot PAC-2 (56 for PAC-2/3) in eight launchers.

Missile cost is an issue as "the PAC-3 is the largest single item in MEADS procurement," says Strickland. He believes Lockheed Martin's price for the missile will be below the threshold for affordability by the time procurement begins for MEADS, which is scheduled to enter service around 2012. Production of missiles usable in either system is expected to begin by 2005.

Work on MEADS is split between the USA with 55%, Germany with 28% and Italy with 17%, but is being performed by "virtual" integrated product teams, says Strickland. Development is due to begin in 2004 after completion of the risk-reduction effort, towards the end of which the team plans an integrated system demonstration involving both software simulations and hardware prototypes, including the phased-array surveillance and fire-control radars.

In service, first PAC-3 then MEADS will form the lower tier to THAAD's upper tier in an anti-TBM architecture intended to be "near leak-proof", says Tom McGrath, THAAD programme manager at Lockheed Martin Missiles & Space. A mobile system designed to protect forward-deployed forces and civilian assets, THAAD is the only US missile defence system designed to perform both endo- and exo-atmospheric interceptions, he says.

The system, now in development, has four main elements: ground-based radar, battle manager, launcher and missile. Raytheon is developing the X-band phased-array radar - the only element of the system that is not transportable byC-130, requiring a Boeing C-17 or Lockheed C-5. While the launcher has been redesigned to fit in a C-130, "we can't reduce the size of the radar without reducing its performance", McGrath says.

THAAD entered development in mid-2000 after only two successful TBM intercepts, which followed six failures. Thesingle-stage missile carries a kill vehicle that separates and steers towards the target using an infrared seeker and a divert and attitude control system. The "next generation" missile now under development features improved booster thrust-vector control, and a divert system with 10% more thrust and 40% more fuel.

Flight tests are scheduled to resume in 2004, with intercepts due to begin in 2005. The 16 tests planned will begin with exo-atmospheric intercepts and progress to the more difficult endo-atmospheric engagements, McGrath says. The US Army plans to have the first unit equipped in 2007, but the initial configuration "does not do what the customer wants", he says. Further development will be required if THAAD is to meet the system specification.

Lockheed Martin has begun a company-funded effort to extend THAAD's capability into intermediate and intercontinental ballistic missile defence, following the USA's withdrawal from the Anti Ballistic Missile (ABM) treaty. "The system was designed to meet the ABM treaty. Now we can look at the opportunity to grow the capability," McGrath says.

The US Army's intention to acquire 13 radars and 1,250 missiles to equip eight or nine THAAD batteries appears ambitious given its plans for PAC-3 and MEADS, and its need to extend the life of current Patriot batteries to keep them in service until around 2030. Perhaps sensing the US Army may need another, lower-cost option to the replacement of Patriot, Raytheon is proposing a series of upgrades including a hit-to-kill version of the existing missile.

"Raytheon is trying to propose smart things to do to the system to keep it modern and viable," says Patriot business development manager Dave Hartman. "The US Army has a recapitalisation programme for the fielded systems, which were built in the 1980s, to eliminate obsolescence and make them more reliable. We want to offer ideas that will get a better bang for the buck, and turn recapitalisation into modernisation."

Patriot improvements

On internal funding, Raytheon is working on three elements of the Patriot system: radar, command and control and missile. While the radar's transmit side is being enhanced under the PAC-3 programme to increase power and introduce TBM classification and warhead discrimination, the company has developed a digital signal processor which could remove over half the electronics on the receive side. This would allow the radar to be truck-mounted and C-130-transportable.

"Our focus is on the deployability of Patriot," says Hartman. "Today it needs the C-5 or C-17. We want to give it C-130 deployability." New computers and displays would allow the control station to be repackaged from a truck onto two Humvees and the US Army has given Raytheon funding to complete development of a lightweight, electrically driven communications mast that fits on a Humvee rather than a truck.

The proposed missile modernisation involves adding hit-to-kill capability in the form of an active seeker, thruster package and rod warhead. Raytheon demonstrated an active-seeker Patriot in two cruise missile intercepts in 1999, Hartman says. No radar or launcher modifications would be required and the standard 405mm (16in)-diameter missile would have greater range and altitude capability and six times the kinetic energy of the 255mm-diameter PAC-3 interceptor, he says, adding that development is low risk and would take just two years.

With MEADS only funded for the risk-reduction phase, Raytheon senses an opportunity. "MEADS in not a near-term reality, it is mid-term - 2012-15 - and it may not go ahead," Hartman says. "But MEADS or no MEADS we need to focus on extending Patriot's service life."

Source: Flight International