The Harpoon family of anti-ship missile has been in US service since the late 1970s. At the time of its introduction, it was cutting edge technology in small sized, sea skimming cruise missiles. But today, it is rapidly becoming obsolete.
It’s range of roughly 100 nautical miles is a good deal less than the 150nm minimum that the Navy needs to stand off from enemy missile armed ships. The Harpoon’s radar seeker was pretty advanced when introduced, but today is increasingly vulnerable to jamming or deception. And while the canister launch system is quite compact, ships such as the Flight IIA DDG-51 Burke class destroyers don’t have space for even such a small mount. Ideally, any next generation anti-ship missile will fit inside the existing Mk41 Vertical Launch System that houses all the other missiles these ships carry.
Also, the Navy would like any future Anti-Ship missile to also be able to be carried and launched by existing strike aircraft like the F/A-18 Hornet family, and ideally the F-35C.
Rather than starting from scratch, the Navy has been looking around at what else is already available.
And coincidentally, the Air Force began a replacement for its air launched cruise missiles a few years ago. And the fruits of that program recently entered service as the AGM-158 JASSM, or Joint Air to Surface Standoff Missile. A longer ranged variant has even more recently entered service as the JASSM-ER, or Extended Range.
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Accordingly, the Navy, via DARPA, has begun developing a variant of the JASSM-ER as a next generation Anti-Ship Missile. This program is known as LRASM, or Long Range Anti-Ship Missile.
Unlike a cruise missile designed to attack targets ashore, Anti-Ship Missiles need to attack moving targets. That means they need an autonomous seeker capability to detect and track the target. Traditionally, this has meant a radar seeker. The Lockheed Martin, the contractor, advertises the seeker as having a multi-mode capability, which, just guessing here, includes a radar seeker, possibly a passive electronic seeker, and most likely an imaging infra-red and possibly a ultraviolet spectrum seeker.
The LRASM is powered by a small jet engine for cruising to the target. But to get it up to flight speed, it needs a rocket booster. To save development costs, the LRASM is using the Mk114 booster rocket currently used by the Vertical Launch ASROC anti-sub weapon.
Leveraging existing weapons and technologies allows for the relatively low risk development of a weapon system that is cheaper than starting from a fresh sheet of paper, and yet still provides a significant improvement in capability over the currently fielded Harpoon family.
The Navy hasn’t made any announcements, but it is quite possible that the LRASM will also be developed into a land attack variant to replace the existing Tomahawk cruise missiles.