RIM-161 Standard Missile 3 - Operation and Performance

Operation and Performance

The ship's AN/SPY-1 radar finds the ballistic missile target and the Aegis weapon system calculates a solution on the target. When the missile is ordered to launch, the Aerojet MK 72 solid-fuel rocket booster launches the SM-3 out of the ship's Mark 41 vertical launching system (VLS). The missile then establishes communication with the launching ship. Once the booster burns out, it detaches, and the Aerojet MK 104 solid-fuel dual thrust rocket motor (DTRM) takes over propulsion through the atmosphere. The missile continues to receive mid-course guidance information from the launching ship and is aided by GPS data. The ATK MK 136 solid-fueled third stage rocket motor (TSRM) fires after the second stage burns out, and it takes the missile above the atmosphere (if needed). The TSRM is pulse fired and provides propulsion for the SM-3 until 30 seconds to intercept.

At that point the third stage separates, and the Lightweight Exo-Atmospheric Projectile (LEAP) kinetic warhead (KW) begins to search for the target using pointing data from the launching ship. The Aerojet throttleable divert and attitude control system (TDACS) allows the kinetic warhead to maneuver in the final phase of the engagement. The KW's sensors identify the target, attempt to identify the most lethal part of the target and steers the KW to that point. If the KW intercepts the target, it provides 130 megajoules (96,000,000 ft·lbf, 31 kg TNT equivalent) of kinetic energy at the point of impact.

Independent studies by some physics experts have raised some significant questions about the missile's success rate in hitting targets. In a published response, the Defense Department claimed that these findings were invalid, as the analysts used some early launches as their data, when those launches were not significant to the overall program. The DoD stated:

...the first tests prototype interceptors; expensive mock warheads weren’t used in the tests since specific lethality capability wasn’t a test objective—the objective was to hit the target missile. Contrary to the assertions of Postol and Lewis, all three tests resulted in successful target hits with the unitary ballistic missile target destroyed. This provided empirical evidence that ballistic missile intercepts could in fact be accomplished at sea using interceptors launched from Aegis ships.

After successful completion of these early developmental tests, the test program progressed from just “hitting the target” to one of determining lethality and proving the operationally configured Aegis SM-3 Block I and SM-3 Block 1A system. These tests were the MDA’s most comprehensive and realistic test series, resulting in the Operational Test and Evaluation Force’s October 2008 Evaluation Report stating that Aegis Ballistic Missile Defense Block 04 3.6 System was operationally effective and suitable for transition to the Navy.

Since 2002, a total of 19 SM-3 missiles have been fired in 16 different test events resulting in 16 intercepts against threat-representative full-size and more challenging subscale unitary and full-size targets with separating warheads. In addition, a modified Aegis BMD/SM-3 system successfully destroyed a malfunctioning U.S. satellite by hitting the satellite in the right spot to negate the hazardous fuel tank at the highest closure rate of any ballistic missile defense technology ever attempted.

The authors of the SM-3 study cited only tests involving unitary targets, and chose not to cite the five successful intercepts in six attempts against separating targets, which, because of their increased speed and small size, pose a much more challenging target for the SM-3 than a much larger unitary target missile. They also did not mention the fact the system is successfully intercepting targets much smaller than probable threat missiles on a routine basis, and have attained test scores that many other Defense Department programs aspire to attain.