An older "Matchbox" ASROC launcher, phased out in the 1990s

ASROC (for "Anti-Submarine Rocket") is an antisubmarine missile system, developed by the United States Navy, and installed on over 200 surface ships, generally cruisers and destroyers. A surface ship first detects an enemy submarine by using sonar, then fires an ASROC missile, which has a torpedo or depth charge on the tip, toward the target. Once the missile's rocket motor stops firing, the torpedo breaks away and a parachute slows it down until it enters the water. The torpedo's motor then activates and the torpedo, which is guided by its own sonar system, homes in on the target and explodes. (Alternatively, if the missile is instead equipped with a depth charge, it merely sinks to a predetermined depth and then explodes.) An ASROC missile can carry either a nuclear or conventional explosive, although the nuclear depth charges were phased out by the 1990s.

The first ASROC system, using the MK-112 "Matchbox" launcher, was developed in the 1950s and installed in the 1960s. This system was phased out in the 1990s and replaced with the Vertical Launch ASROC, or "VLA".

Launch of a Vertical Launch ASROC

The VLA missile is a rocket-propelled, three-stage, anti-submarine warfare (ASW) weapon designed for deployment on Ticonderoga-class cruisers, Arleigh Burke-class destroyers, and Spruance-class destroyers equipped with the MK41 Vertical Launching System (VLS) and MK 116 fire control system. The VLA missile provides the fleet with the capability for rapid response, all weather delivery of a MK 46 torpedo against threat submarines in any direction at intermediate ranges. VLA missiles were introduced into the fleet in 1993 as a baseline weapon for the cruisers and destroyers equipped with the Aegis combat system and as a replacement for the ASROC weapon on Spruance-class destroyers when the original ASROC launchers were replaced by the MK 41 VLS.

VLA missiles were first introduced with the MK 46 torpedo as its payload (RUM139A). In 1996 an upgrade was implemented to allow the enhanced shallow-water capable MK 46 to be incorporated as the VLA missile payload (RUM139B). VLA missiles are delivered to the fleet as All-Up-Rounds (AURs) which consist of the VLA missile installed inside of a MK15 VLS canister. VLA missiles have two basic fleet configurations, Warshot and Exercise. VLA Warshot missiles contain a MK46 warshot torpedo. VLA Exercise missiles contain an exercise torpedo, and are used for fleet exercise firings.

General Characteristics of the VLA

• Primary Function: Surface Launched Missile, Anti-Submarine Warfare Weapon.
• Contractor: Lockheed Martin, Naval Electronics & Surveillance Systems - Akron, Ohio (formerly Loral Defense Systems, formerly Goodyear Aerospace).
• Unit cost: Approximately $350,000 (less torpedo payload).
• Power plant: Solid propellant rocket motor.
• Length:
  • Warshot: 16 ft 0.6 in (4.892 m)
  • Exercise: 16 ft 8 in (5.08 m)
• Weight:
  • Warshot: 1407 lb (638 kg)
  • Exercise: 1377 lb (615 kg)
• Diameter: 16.6 in (422 mm)
• Wing Span: 26 7/8 in (683 mm)
• Range: ASW Intermediate range
• Guidance system: Inertial Guidance
• Warhead: MK 46 torpedo, 100 lb (45 kg) of PBXN-103 high explosive
• Date Deployed: 1993 (RUM139A); 1996 (RUM139B)