Friday, October 5, 2012

Ship Self-Defense System (SSDS)

Here’s a little-known system that is critical to Navy ship survivability and yet is struggling to achieve effective and reliable operation – the Ship Self-Defense System (SSDS).  SSDS is intended to be the self-defense weapons control system for all carriers, amphibious ships, and LCS.  The system comprises software and networking which links existing, legacy sensors to existing and new weapons.  Supported weapons include, notably, Rolling Airframe Missile (RAM) and Evolved Sea Sparrow Missile (ESSM).  In concept, any sensor or any weapon can be added to the system through software modifications.

In their 2011 Annual Report, DOT&E stated the following.

“… the ability to effectively complete the self-defense mission against the types of threats for which the overall system was designed has not been successfully demonstrated. In addition, reliability problems further degrade the ships’ ability to complete this mission.”
ESSM - Part of a Troubled System

Several ship classes including the LPD-17 and CVN-68 carriers have been evaluated as unable to meet their self-defense requirements.  This doesn’t mean that the system is totally inoperable, only that aspects of the threat spectrum can’t be reliably countered, as yet.  For instance, the report describes the CVN-68 problems,

“The CVN-68 ship class combat system has several problems that keep it from successfully completing the ship self-defense mission. Specific problems include deficiencies in weapon employment timelines, sensor coverage, system track management, and North Atlantic Treaty Organization (NATO) SeaSparrow Missile System performance, as well as deficiencies with the recommended engagement tactics provided for use against multiple ASCM threat classes.”
One of the common and continued problems is that the physical placement of some of the legacy sensors has proven to be sub-optimal, leading to detection difficulties in some scenarios. 

One of the major issues identified in the report is a lack of realistic threat surrogates which will allow meaningful testing.  This is a several year, standing criticism/recommendation to the Navy from DOT&E.  We’ve covered this general issue in multiple posts.  I find it disturbing that year after year the Navy somehow finds the funds to build new ships but makes little or no attempt to field realistically performing threat drones so as to test and develop the self-defense systems that will keep the new ships afloat.  The Navy’s internal priority is new construction at the expense of maintenance, training, testing, and so on.  Navy leadership has their priorities completely ass-backwards and they desperately need to wake up as Adm. Harvey urged in his farewell note to the fleet.

DOT&E issued a classified report to Congress on the SSDS program in March of 2011 describing details of the problems.

This is one of those posts about which I have no meaningful analysis beyond the Navy’s scrambled priorities.  Consider this simply interesting information that is worth keeping an eye on because it is the backbone of so many ships.


  1. The SSDS is an attempt to back-fit something as good as Aegis for short ranges on non-Aegis warships. In my view it is a very difficult proposition.

    As I said in other posts, Aegis has four arrays that each “stare” at a 90 degree quadrant of the sky surrounding the ship. Conventional rotating radars like SPS-39 or 48 sweep around the ship. No matter how quick they rotate, they lose track of their targets momentarily and have to reacquire on each pass.

    If the target is a bomber 100 miles away, this is no problem. But an incoming supersonic sea-skimming cruise missile is very different.

    If there is only a minute to acquire and react, then you can’t spend a portion of it reacquiring.


    1. WGM, are you suggesting that the Navy wasted time and money trying to make inadequate legacy sensors do something they're not capable of doing and that, instead, the Navy should have been looking at retro-fitting SPY-1K/-1F arrays or, at least, rapid scan units like the TRS-3D or Sea Giraffe which are fitted on the LCSs?

      On a related note, one of the capabilities of the SSDS is supposed to be the ability to fuse separate signal sources into a composite, targeting quality "picture". So, even if one sensor is rotating and losing the target, another sensor should be acquiring it and filling in the "gap". For instance, the SPS-48/-49 in conjunction with the SPQ-9B should provide better coverage. Or, so the story goes. Who knows? Apparently, it's not working so well in practice.

  2. I'm not going to say the Navy wasted their time. When this program first started it seemed like a very good idea. But I think they have run into a real thorny problem of sequencing and collating the radars and any other sensors into that one big picture of everything that is around the ship. It may be that it cannot be done. Or it will take a lot longer and cost more than expected. I don't think the New Threat Upgrade really addressed future ASCMs so the SSDS has been breaking new ground.

    My opinion on this is that if all the bugs on SSDS are worked out, it will be still be difficult to handle ASCM at supersonic speeds. To be fair, an Aegis ship will have very little time to react to a Mach 2 sea-skimmer. But the dwell time the SPY-1 can put on a threat will be uninterrupted during that brief window. I believe that could make the difference between success and failure.

    You must have read my mind; I thought of the SPY-1F as I posted earlier. That's the only relatively lightweight system capable enough of dealing with possible future ASCM threats.

    As an example if Russia or India start exporting the BrahMos missile aggressively we have a real threat, right away.

    I used to think the Norwegian, Danish, and Spanish navies were crazy to buy the SPY-1F and put it in a small hull. There is very little room for the VLS, even if some missiles are quad-packed ESSM. But I can see they are thinking about future threats and want their FFG or DDG to be relevant for their entire service lives. They cannot afford a Kongo or KDX-III but they want their ships protected against missiles.


  3. Replies
    1. That's a fascinating concept that I was unaware of. Thanks for the link!

  4. How light weight is SPY-1F?

    Why not SPY-3? It doesn't have the same range or volume search capability, but AESA lets you do all kinds of fancy things like illuminate while scanning and periscope detection. Plus all three faces can scan simultaneously. They aren't limited by the number of magnetrons.

    Pair it with a long-range search radar like SPS-48 or SPS-49.

    Of course it isn't exactly OTS yet.

    1. As WGM said above, the original SSDS concept was to tie existing sensors and weapons together in a comprehensive combat control suite which would provide a major boost to self-defense without requiring any new sensors or weapons. It's proving to be a tough thing to accomplish.

      I think you're suggesting that we stop trying to integrate sensors that are proving problematic and instead substitute a single radar that doesn't require nearly as much integration as several individual ones. If that's what you're driving at, that's certainly worthy of consideration. Good thought!

    2. I don't think it needs to be a single sensor.

      The problem with trying to fuse existing systems is that they all have well-known limitations. SPS-48 rotates at a pokey 15 rpm. That's 4 full seconds between refreshes. A supersonic cruise missile can travel a long ways in 4 seconds. SPQ-9B is better. It rotates at 30 rpm and has back-to-back arrays. But it is a short-range system.

      SPY-3 promises to fix these issues, along integrating ESSM illumination and other modes, and can rapidly interleave different modes.

      Of course it's much heavier and more expensive than those other radars. And it isn't in service yet.

      SPY-5 is another potential player, but I haven't heard much about it. It could replace SPQ-9B.

  5. Another option is CEAFAR/CEAMOUNT.

  6. Yet another option is Elta EL/M 2248, though of course it's Israeli.

  7. So is the Lightning ATP but we use it anyways.

    How about mounting 3-4 APG-81s (regular size at first and maybe with larger arrays later) in a triangular setup? Since the EODAS is already headed to sea it would drive down the cost of both.

    While you're at it, use the ESM, EOTS, and ICP since the integration is done? :)

    All you need to do is figure out where to put the lift-fan :)

    But in all seriousness, why do we keep reinventing the wheel?

    Follow the example of JSF and make a COTS solution that is open architecture and UAI (extended to sensors).

  8. With Israel willing to sell advanced technology to China, I wouldn't want to depend on an Israeli anti-missile radar to potentially defend against Chinese cruise missiles.

    Lightning ATP is less worrisome, IMHO. It's not a core defensive system protecting high-value targets.

  9. This comment has been removed by the author.

  10. The ESSM is an interesting animal. Kinematically it is one of the best horizon range SAMs in world. The lack of a need to go 100~150km means that it uses an all-boost motor pushing it up to Mach 4 (at altitude). It's folding fins make it very compact and lets you quad pack them in a single Mk41 VLS cell. In fact, the motor is so attractive it is almost scandalous that the Navy is not looking at it to power an anti-radiation missile or a long range AAM -- this is something that promises to be more compact (it'll fit in the F-35 internal bays) and out perform the Phoenix. In a supersonic air launch at high altitudes, this is easily a Mach 5.5~6 missile.

    On the other hand as a Point Defense SAM it is plagued by its semi-active seeker. This posses two issues. The first being that it needs an illuminator or an X-band phased array radar capable of interrupted continuous wave (ICW) illumination. This is problematic because many ships such as Corvettes and LHDs simply don't have the illumination apparatus to support the ESSM. The second problem is that the radar horizon of many smaller vessels is about 25 km against sea skimming targets. This gives you about 1 minute against a high subsonic missile and about half a minute against supersonic ones if you are limited by this horizon. If you are limited to 1 or 2 ESSMs in the air a minute you are easily quite saturated.

    The ESSM, perhaps more so than the SM-6, can really use the AMRAAM seeker. Such an ASSM or "Active Sea Sparrow Missile" will allows ships to field this weapon with nothing more than a Sea Giraffe or SPQ-9B search radar. It will also allow a dozen missiles in the air without the limitations imposed by time sharing limited illumination resources. Such a missile actually exists! It's called the SL-AMRAAM-ER, why it isn't being Navalized for the ship point defense role is puzzling, especially given that the AMRAAM seeker can function in a semi-active mode if you want it to.

  11. Well, technically speaking, carrier sentry concepts don't require switching hulls, but being able to does reduce losses.

  12. The missile successfully engaged aerial threats during the combat system ship qualification trial of the Nimitz-class aircraft carrier USS Theodore Roosevelt in May this year.