RIM-161 Standard Missile 3
The RIM-161 Standard Missile 3 is a ship-based surface-to-air missile used by the United States Navy to intercept ballistic missiles as a part of Aegis Ballistic Missile Defense System. Although primarily designed as an anti-ballistic missile, the SM-3 has also been employed in an anti-satellite capacity against a satellite at the lower end of low Earth orbit. The SM-3 is primarily used and tested by the United States Navy and also operated by the Japan Maritime Self-Defense Force.
Development
The SM-3 evolved from the proven SM-2 Block IV design. The SM-3 uses the same solid rocket booster and dual thrust rocket motor as the Block IV missile for the first and second stages and the same steering control section and midcourse missile guidance for maneuvering in the atmosphere. To support the extended range of an exo-atmospheric intercept, additional missile thrust is provided in a new third stage for the SM-3 missile, containing a dual pulse rocket motor for the early exo-atmospheric phase of flight.Initial work was done to adapt SM-3 for land deployment to especially accommodate the Israelis, but they then chose to pursue their own system, Arrow 3. A group in the Obama administration envisioned a European Phased Adaptive Approach and SM-3 was chosen as the main vector of this effort because the competing U.S. THAAD does not have enough range and would have required too many sites in Europe to provide adequate coverage. Compared to the GMD's Ground-Based Interceptor however, the SM-3 Block I has about to of the range. A significant improvement in this respect, the SM-3 Block II variant widens the missile's diameter from, making it more suitable against intermediate-range ballistic missiles and intercontinental ballistic missiles.
The highly modified Block IIA missile shares only the first-stage motor with the Block I. The Block IIA was "designed to allow for Japan to protect against a North Korean attack with fewer deployed ships" but it is also the key element of the EPAA phase 3 deployment in Europe. The Block IIA is being jointly developed by Raytheon and Mitsubishi Heavy Industries; the latter manages "the third-stage rocket motor and nose cone". The U.S. budgeted cost to date is $1.51 billion for the Block IIA.
On 15 October 2024, RTX announced that the SM-3 Block IIA entered full-rate production.
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. The Aerojet MK 72 solid-fuel rocket booster launches the SM-3 out of the ship's Mark 41 Vertical Launching System. 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 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 fires after the second stage burns out, and it takes the missile above the atmosphere. 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 kinetic warhead begins to search for the target using pointing data from the launching ship. The Aerojet throttleable divert and attitude control system allows the 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 steer to that point. If the KW intercepts the target, it provides of kinetic energy at the point of impact.
Independent studies of earlier missile versions by some physics experts before 2010 raised significant questions about the missile's success rate in hitting targets. In a published response in 2012, 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.
In an October 25, 2012, test, a SM-3 Block IA failed to intercept a SRBM. In May 2013, however, a SM-3 Block IB was successful against a "complex, separating short-range ballistic missile target with a sophisticated separating mock warhead", making it "the third straight successful test of Raytheon's SM-3 Block IB, after a target was missed on its first intercept attempt in September 2011."
On 4 October 2013, an SM-3 Block IB eliminated the medium-range ballistic missile target at the highest altitude of any test to date. The test was the 26th successful intercept for the SM-3 program and the fifth back-to-back successful test of the SM-3 Block IB missile. Post-mission data showed that the intercept was slightly lower than anticipated, but the systems adjusted to ensure the missile intercepted the target. The SM-3 Block IB is expected to be delivered for service in 2015.
On 6 June 2015, an SM-3 Block IIA was successfully tested. The test evaluated the performance of the missile's nosecone, steering control, and the separation of its booster, and second and third stages. No intercept was planned, and no target missile was launched. In October 2016, Russian officials claimed research simulations of U.S. ballistic missile defense systems showed the SM-3 Block IIA was capable of intercepting missiles not only at the middle stage of their flight path, but earlier in the initial acceleration stage before the separation of their warheads.
On 3 February 2017, USS John Paul Jones, using its onboard Aegis Missile Defense System and a Standard Missile-3 Block IIA interceptor, destroyed a medium-range ballistic missile.
On 21 June 2017, the second test of USS John Paul Jones, using its onboard Aegis Missile Defense System and launching a Standard Missile-3 Block IIA interceptor, did not intercept its target, after a sailor, acting as tactical datalink controller, mistakenly designated that target as friendly, which caused the SM-3 interceptor to self-destruct, as designed.
On 31 January 2018, an SM-3 Block IIA missile interceptor launched from a test site in Hawaii missed its target.
On 26 October 2018, USS John Paul Jones detected and tracked a medium-range ballistic missile target with its Aegis Missile Defense System, launched an SM-3 Block IIA interceptor, and destroyed its target, which was launched from the Pacific Missile Range Facility at Kauai, Hawaii.
On 16 November 2020, an SM-3 Block IIA successfully intercepted a simulated intercontinental ballistic missile target for the first time; the test was congressionally mandated and originally scheduled for May 2020 but was delayed due to COVID-19 restrictions. An ICBM-T2 threat-representative target was launched from the Ronald Reagan Ballistic Missile Defense Test Site on Kwajalein Atoll toward the ocean area northeast of Hawaii. The used off-board sensors through the Command and Control Battle Management Communications network to track it and then launch an interceptor to destroy the threat. The test demonstrated the SM-3's ability to counter ICBMs and, because of the Aegis radar's limited detection and tracking range relative to the interceptor, showed how the C2BMC network can increase the area that could be defended using engage-on-remote capabilities.
During the April 2024 Iranian airstrikes on Israel, the SM-3 was deployed for the first time in combat. The USS Arleigh Burke and USS Carney fired several interceptors towards Iranian ballistic missiles.
Variants
The SM-3 block IA version provides an incremental upgrade to improve reliability and maintainability at a reduced cost.The SM-3 block IB, due in 2010, offers upgrades which include an advanced two-color infrared seeker, and a 10-thruster solid throttling divert and attitude control system on the kill vehicle to give it improved capability against maneuvering ballistic missiles or warheads. Solid TDACS is a joint Raytheon/Aerojet project, but Boeing supplies some components of the kinetic warhead. With block IB and associated ship-based upgrades, the Navy gains the ability to defend against medium range missiles and some Intermediate Range Ballistic Missiles.
SM-3 block II will widen the missile body to and decrease the size of the maneuvering fins. It will still fit in Mk41 vertical launch systems, and the missile will be faster and have longer range.
The SM-3 block IIA is a joint Raytheon/Mitsubishi Heavy Industries project, adding a larger diameter kill vehicle that is more maneuverable, and carrying another sensor/ discrimination upgrade. It was scheduled to debut around 2015, whereupon the Navy will have a weapon that can engage some intercontinental ballistic missiles.
| Designation | Block | Notes |
| RIM-161A | SM-3 block I | Development version. The SM-3 block I uses the basic SM-2ER block IVA airframe and propulsion
|
| RIM-161B | SM-3 block IA | |
| RIM-161C | SM-3 block IB | Passed critical design review on 13 July 2009. |
| RIM-161D | SM-3 block IIA | |
| None to date | SM-3 block IIB |
A further SM-3 block IIB was "conceived for fielding in Europe around 2022". In March 2013, Defense Secretary Chuck Hagel announced that the development program of the SM-3 block IIB, also known as the "next generation AEGIS missile", was undergoing restructuring. Under Secretary James N. Miller was quoted saying that "We no longer intend to add them to the mix, but we'll continue to have the same number of deployed interceptors in Poland that will provide coverage for all of NATO in Europe", explaining that Poland is scheduled instead for the deployment of "about 24 SM-3 IIA interceptors – same timeline, same footprint of U.S. forces to support that." A US defense official was quoted saying that "The SM3 IIB phase four interceptors that we are now not going to pursue never existed other than on Power Points; it was a design objective." Daniel Nexon connected the backpedaling of the administration on the block IIB development with pre-election promises made by Obama to Dmitry Medvedev. Pentagon spokesman George E. Little denied however that Russian objections played any part in the decision.