Why can't (?) the JASSM target ships?

[GeneralVikus]

The Command database lists the LRASM as being able to hit any kind of target, whereas the JASSM can apparently only target land units. This is the opposite of what I would expect, because a surface ship is obviously easier for a seeker to identify than a ground target among clutter. The two missiles appear to be almost identical - notably, they have the same flight profile and approximate range, and both use an IR seeker; and, of course, one is a derivative of the other. The only apparent difference is that the LRASM also has a jammer and an antiradiation seeker, and the JASSM does not. As such, it seems to me that the designers would have had to go out of their way to make the JASSM somehow unable to target ships. The fact that the Navy does not operate the missile lends credence to the idea that it can't target ships, but of course, it would be exceedingly odd for Australia's F/A-18Fs to use the missile while US F/A-18Fs are physically incapable of doing so, though I understand that adding a missile to an aircraft requires some small programming effort.

The fact that the JASSM is still being acquired at a rate 10x that of the LRASM, which is being procured only in very small numbers by the Navy and tiny quantities by the air force, (despite being in production for six years now,) makes the idea that the JASSM can't be used by naval aircraft or against naval targets even more puzzling. The JASSM may not be optimized for use against ships, since it lacks a jammer and antiradiation seeker, and may have other limitations besides; but surely having the option of targeting ships, even if only by the USAF aircraft which are reportedly certified to carry it, would be better than not having that option.

There are three possibilities that occur to me: firstly, the CMO database is wrong, but I'm sure such a mistake would have already been corrected.

Secondly, the JASSM is perfectly capable of being used against ships and / or being used by USN Hornets, but is not advertised as such so as to create some degree of uncertainty about US anti-ship capabilities. Since the Hornet can carry the LRASM and the two missiles seem to be nearly identical, it's not a stretch to assume that it can use both; even if it's never been publicly tested with the JASSM, how could anyone tell which one of the two missiles was being dropped in a test firing? However, considering that, (for instance,) the Soviets apparently assumed that the Pershing II had at least the same range as the SS-20, even though such a claim ought to be far easier to disprove than the ability or inability of a missile to target a ship, it seems unlikely that anyone would be taken in by such a ruse, unless I'm missing something obvious.

Finally, I suppose there could be some kind of countermeasure which modern ships can use to easily and cheaply defeat some types of IR seekers but not others, which renders the JASSM ineffective but the LRASM effective against modern ships. Since I don't know anything on the subject, I'll defer to anyone's superior knowledge.

Unless I'm missing something major, I presume this subject must have come up here before, so I hope I am not getting on anyone's nerves by asking this question. Nevertheless, I would really appreciate an answer.

[thewood1]

My understanding is the LRASM has a much more sophisticated, and I assume expensive, targeting and comms package. It has to be able to discriminate type of ship and be able to find a highly mobile target that might change profile randomly. JASSM can probably hit a stationary ship that has a solid track.

[HalfLifeExpert]

A ship target is most likely a moving target, which means the guided weapon needs the right kind of sensor(s) to actively track and adjust it's trajectory as that target moves.

Since the LRASM is built from the existing JASSM, that means the JASSM doesn't have the required sensors to engage a moving target.

Simple as that really, same reason you can't use your TLAMs against ships, even those going extremely slow.

Weapons like JASSM and TLAM are expensive, so you wouldn't be able to just use them with such a low probability of the weapons sensors actually scoring a hit.

[GeneralVikus]

The unit cost of the LRASM is $7.02 million, whereas the unit cost of the JASSM is $3.01 million, so that is a reasonable explanation - the necessary sensor to hit a moving target might be much more expensive. However, there are problems with this explanation. Firstly, the JASSM is being procured in much larger quantities, meaning that part of the unit cost difference is likely due to economies of scale (maybe not, since I think they share the same production line.)

However, more importantly, vastly smaller and cheaper Infared, fire and forget guided missiles (i.e. Maverick, unit cost $110,000 according to wiki) can, to the best of my knowledge, hit moving targets - and in spite of ground clutter. It therefore seems implausible that moving target capability - especially when that moving target is a big, predictable ship against an empty blue background - adds so much expense to an IR seeker. It seems more probable that the antiradiation seeker and ECM add more to the LRASM's cost.

[thewood1]

There is a world of difference between a Maverick IR TV sensor and the AI-driven LRASM sensor. The Maverick has to be locked on from the launching aircraft's detection and targeting system. The LRASM only, in theory, only needs the target programmed into its system and a general location. This is why the original Tomahawk ASM variant was removed. They couldn't get the final targeting system to be dependable without offboard targeting.

The short of it is that the targeting system is the key differentiator and the new comms.

[thewood1]

https://www.popularmechanics.com/milita ... nal-plane/

It is PopMech, so take it for what its worth. But it does give a fairly concise description of LRASM vs JASSM. As a bonus, there's an LM ad for LRASM embedded.

[14yellow14]

It may have residual anti-ship capability, at least in the latest versions if it has two-way datalink. This is something CSIS has wondered about when developing a wargame about the war with China and has a major operational impact if it has a marginal anti-ship strike capability to complement the LRASM against the most demanding targets.

In theory the JASSM with the terminal IIR sensor and updates via datalink could attack moving targets. Unlike the LRASM, it will probably not be able to find them with its own sensors.

https://www.csis.org/analysis/first-bat ... ion-taiwan

[kevinkins]

I think the LRASM can be programed to hit and penetrate just above the water line. While the JASSM might be able to strike the bridge and the sensor mast with an in air blast. In either case, its expensive to take out a modern warship if it has a good well trained crew.

[thewood1]

Actually, one of the big differences with the LRASM's new SW is that it has a higher resolution sensor and imaging database. This allows very specific areas of the ship to be targeted. I suspect this also required a change in its controls as well. How well that executes in the field is a guess right now.

[rvseydlitz]

Also the mentioned Maverick, etc, fire at a target mere seconds away that cannot move very far in those seconds. The JASSM fires at buildings that do mot move at all. LRASM fires and can fly a half hour on the way to its target which can move 6-16 miles away in that half hour.

[wrgmlvr]

A ship target is most likely a moving target, which means the guided weapon needs the right kind of sensor(s) to actively track and adjust it's trajectory as that target moves.

Since the LRASM is built from the existing JASSM, that means the JASSM doesn't have the required sensors to engage a moving target.

Simple as that really, same reason you can't use your TLAMs against ships, even those going extremely slow.

Weapons like JASSM and TLAM are expensive, so you wouldn't be able to just use them with such a low probability of the weapons sensors actually scoring a hit.

agree