Senin, Februari 15, 2010

Israel Upgrades Its Antimissile Plans

The U.S. and Israel have started development of an upper-stage component to Israel’s Arrow-3 missile defense architecture. Arieh Herzog, director of Israel’s missile defense program, says the main element will be a highly maneuverable exoatmospheric interceptor that zeros in on an incoming missile.

The decision to add the component, which will be jointly developed by Israel Aerospace Industries (IAI) and Boeing, stems from a study conducted in 2006‑07 that identified a need for it in Israel’s ballistic missile defense system.

Meanwhile, given the urgent need to meet the growing ballistic missile threat from Iran, IAI is pressing ahead with the Arrow-3 antiballistic missile, the development of which is being funded partly by the U.S. IAI displayed a full-sized model of the two-stage Arrow-3 at the Paris air show last year. It is slightly smaller than the Arrow-2 missile in service, but is designed to engage and intercept clusters of hostile missiles at higher altitudes in the upper atmosphere. Uri Sinai, general manager of IAI’s missile division, says the Arrow-3 will be the world’s first multi­tiered, unified antimissile system, providing Israel’s Homa national missile-defense strategy with an effective exoatmospheric kill vehicle (KV).

Joseph Hasson, chief missile designer at IAI’s MLM systems integration division, presented the concept at a conference last year. The presentation suggested a revolution in exoatmospheric KV design, in which existing technologies will be used to achieve a high level of simplicity and effectiveness that has not been possible in similar weapons. Hasson and MLM colleague Galya Goldner have, in fact, patented the new KV.

The KV developed by the IAI team has an exceptionally broad divert capability. This means the kill vehicle will be able to maneuver in space and close in on a target at high speed, thus yielding a high probability of a kill. Unlike most KVs, which use liquid or gas propulsion, the Israeli KV will be propelled by an ordinary rocket motor equipped with a thrust-vectoring nozzle.

The KV will also be fitted with a gimbaled seeker for hemispheric coverage. By measuring the seeker’s line of sight relative to the vehicle’s motion, the KV will use proportional navigation to divert its course and line up exactly with the target’s flight path. Hasson says the concept is relatively simple, reliable and inexpensive, and is based on mature technologies. Furthermore, the KV’s divert capability and agility reduce the need for detection and tracking systems, which usually accompany remote sensor-assisted exoatmospheric kills.

Another presentation, by Idan Paiss, also from MLM, discussed imaging systems for ballistic missile interceptors. Paiss argued that a combined sensor using visible and infrared elements would be suitable for a ballistic missile intercept under all lighting conditions. When provided with the high-density arrays available today, such sensors could provide target detection, discrimination and tracking, as well as assist in line-of-sight measurement using star tracking.

The new upper-tier component will require the integration of longer-range detection, tracking and discrimination capability beyond what the Green Pine and advanced Green Pine radars used with Arrow-2 provide. Among the advanced sensors considered for Israel’s future multitier system are airborne electro-optical sensors deployed on high-flying unmanned aerial vehicles and enhanced Green Pine radars, as well as the AN/TPY-2 radar deployed in Israel and operated by U.S. forces.

The U.S. Missile Defense Agency (MDA) has asked Congress to approve an allocation of $120 million for U.S.-Israel cooperative missile-defense efforts.

“The U.S. and Israel have cooperated on missile defense for over 20 years,” Lt. Gen. Patrick O’Reilly, MDA director, told the House Armed Services subcommittee for strategic forces. “New joint programs have advanced this cooperation. The Arrow-3 promises to be an extremely capable system, more advanced than what we have attempted in the U.S. with our programs.”

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