Geoff FordenDF-21 Delta: Some Early Thoughts

The so-called DF-21D is much in the news recently, mostly because it hasn’t shown up yet.  It is reputed to be the anti-ship version of China’s short-range workhorse, the DF-21.  (China uses some version or other of the DF-21 for short-range ballistic missiles, anti-satellite weapons, and ballistic missile defense.)  I thought I’d start the analytical discussion of this virtual missile by making some simple calculations about what sort of transverse accelerations its terminal phase guidance and control systems are going to need.

The first point to make is that (unless it is using a nuclear warhead) it is going to need terminal guidance to fine tune the warhead’s trajectory as it reenters the Eearth’s atmosphere.  This is true regardless of how well China needs the position of the target carrier—the only target worthwhile shooting at.  Consider the scenario China’s military must assume: as soon as a DF-21D is launched (and hence detected by US early warning satellites) every carrier anywhere near the missile takes off at maximum speed in some random direction.  If the DF-21D is launched at maximum range (again something China’s military planners would need to assume), each ship could be some 13 km away from where it was a the time of launch.  The DF-21D would have to correct for that change sometime during its flight.  The most logical place to correct for those changes are sometime after the end of the boost phase since the target carriers—the only targets worth shooting at—can zig and zag at anytime.

Thrusters vs. Fins

The answer is, of course, both if you got ‘em.  But each mechanism for changing the warhead’s trajectory will require its own target tracking system.  Ideally, you want to make changes in trajectory as early as possible since the longer you have to accelerate to the new trajectory, the lower the magnitude of the required trajectory (and, among other things, the more control you have over the final result).  If the DF-21D warhead uses infrared sensors—putting aside the question of whether or not China has the required technology for a moment—then it will have to use them during the coast phase of its trajectory.  Otherwise, the heat of reentry will blind the sensor if it tries to use them after it reenters the atmosphere, say something like 50 km altitude to pick a round number.

At these altitudes, the warhead cannot use aerodynamic surfaces to change its direction.  So it will need thrusters—little rocket engines—to change its direction.  Of course, China does has plenty of experience with fine tuning trajectories with small thrusters from its satellite insertion operations.  The most likely method China might use for such a platform is a “bus” that holds the warhead while little thrusters change its position.  What sort of thrust would they need?  Assuming the warhead makes its corrections as the warhead passes below 100 km altitude in order to minimize the time the target has for changing its direction (again, I’m pulling these numbers out of thin air) it would have enough umph to change the velocity of the warhead/bus combination by 0.6 km/s.  (This is calculated by assuming the thrusters need to change the direction of the warhead by 13 km in the 22 seconds the warhead has between when it passes 50 km—the minimum altitude I assume it can still use IR sensors).  That, in turn, requires a little more than three G’s (three times the acceleration of gravity).  That is probably about the requirements needed for China’s ASAT weapon tested in January 2007.  So that seems possible.

If the warhead shuts down its IR sensor as it passes 50 km altitude, it is about 22 seconds before impact.  It is too much to hope that the carrier can change its direction or even its speed in those few remaining seconds so the we can expect; the George H. W. Bush displaces 100,000 tons!  That means the warhead can “safely” extrapolate the position the carrier will be 22 seconds after its tracker shuts down.  During those 22 seconds, the Bush could travel 370 meters, which is about the length of the Bush (333 meters) but five times the beam of the Bush (77 meters).  How likely a hit will be will depend on two things: how accurately the tracking system can determine the position and velocity and how finely it can tune its acceleration to match the desired trajectory.

If, for some reason, China relies solely on aerodynamic surfaces for maneuvering then it will have to wait until it gets even closer to the Earth’s surface for really effective control.  Let’s assume it needs to wait until its 30 km above the Earth’s surface before the warhead’s fins “bite.”  Of course, it could have stored the needed maneuvers from an IR sensor that shut down several seconds before it started maneuvering.  On the other hand, it could use a radar to track the target since 50 km is well within the range of most radars mounted on fighter jets today.

At 30 km, the warhead is 13 seconds before impact.  If it has to do all its maneuvering to cover the 13 km assumed miss distance, than it will need to change its velocity by nearly 1 km/s.  That, in turn, will need an acceleration of 7 G’s.  That is certainly possible achieve using only aerodynamic surfaces (SCUD warheads probably had nearly 10 Gs of transverse acceleration as they corkscrewed during their reentry during the first Gulf War).  However, it needs to be very finely tuned and that seems the hardest point.  No matter what, it would require considerable testing to develop.

Is a DF-21 Anti-Ship Missile Possible?

These rather simple calculations have shown that both types of guidance and control for an anti-ship ballistic missile are possible.  But both would be pushing China’s technology considerably.  For instance, China can most likely build mid-infrared detectors for military space applications.  These might be used for their missile defense interceptor, even though they are barely applicable for anti-satellite weapons.  Could they be used for an anti-ship application?  Possibly.  They could certainly see through most clouds so cloud cover is not an issue.  But it would take more thought than I have given it to know that it could discriminate between a ship and the ocean.  Radars, which with their limited range would require aerodynamic maneuvering, seem even more problematic because of the need to control large accelerations.

So, while I cannot rule out the DF-21D on first principles, it would need a sustained test and evaluation program no matter what technology it used.  I, for one, am unaware of China undertaking such an extensive test program.


  1. Andy (History)

    How does warhead design fit into it, such as unitary vs some kind of submunition? I would think a submunition design would improve chances for something to hit the carrier (especially if missiles are fired in salvos) by somewhat decreasing needed precision and accuracy to score a hit.

  2. Azr@el (History)

    IR sensors, 50km? On a ballistic missile bus? I think you’ve read a bit too much Science Fiction. A guided ballistic missile targeted against a static target uses a far more mundane prong antennae that juts out beyond the plasma shroud to capture GPS/GLONASS/Beidou-2 updates to its on-board inertial navigation system. Against a moving target, such a ballistic missile, in addition to the GPS feed, would have an additional channel feeding targeting data; last known position, vector, etc… from a recce sat, UAV, submarine, etc….

    For an anti-ship version of the DF-21, the missile would require minimal modifications, the real investment would be in a tracking system; whether space based or terrestrial.

  3. Andrew Tubbiolo (History)

    The testing program would be the best real measure if this system were real. If memory serves the first indication of this was a UAV and radar network covering the South China Sea. If the Chinese are really going to head in this direction they’re going to be pressured to have some sort of Pacific wide maritime patrol capability. So I’d expect to see development of a Chinese RORSAT like satellite so they can monitor the comings and goings of the US, Japanese, and Korean navies. Not to mention any new friends they will make as they strike out into the Pacific and Indian oceans. The real killer ap for a system like this would be to add a 3rd stage and go global so you could attack Naval forces in port and in transit. But again you’d see the testing program years out.

  4. George William Herbert (History)

    Don’t assume carriers can’t maneuver much in 22 seconds; most iron bombs dropped in WW 2 had fall times not much longer than that and missed by wide margins as carriers and other ships changed direction rapidly. Knowing when the key 22 sec period is might be hard for the defender, though.

    Midcourse guidance updates might be passive, rather than active, as well. A lot of antiship missiles take a datalink update that way. As long as whatever provided the initial target position indication can provide an update halfway through missile flight or later, you can get a lot of the target position uncertainty reduced.

    There are terminally guided submunitions listed in media descriptions, but not how many or how big. They list destroying aircraft, the control tower, and “penetration” but no particular details that I know of.

    It’s important to take this with somewhat of a grain of salt. Various Russian antiship missiles were described as the end of carriers in the 80s; SM-2 improvements and F-14s with Phoenix missiles to engage missile carriers out at the edge of engagement range made those less of a threat.

    DF-21D warheads are SM-3 engageable exoatmosphericaly and SM-2 engageable on terminal descent. You can see them coming 1000+ km away on radar due to the trajectory, and the launch warnings from satellites should be robust. They’re a threat – but it’s not clear if it’s really that much worse than prior threats.

  5. jeannick (History)

    during the latest celebratory parade of the PRC
    amongst the usual military stuff on display , there was a drone with a small AWACS looking dome ,
    I assumed it was a naval recc drone or a fake to freak out the U.S. Navy

    one thing is for sure , there will be drones constantly seeking any U.S. task force

  6. blowback (History)

    An aircraft carrier is of little use until the combat radius of the aircraft it is launching reaches the likely target so flying F/A-18s with a combat radius of 449 mi (according to Wikipedia) means that for those aircraft to operate over Taiwan an American carrier would have to be within about 600 mi of the Chinese mainland. Anything beyond that and the Chinese needn’t bother about it as all it will be capable of defending is sea and the Chinese aren’t interested in that.

    Again according to Wikipedia, the DF-21D will be capable of Mach 10.0 or 7,680 mph. So that gives a flight time of between ~8 minutes. At 35 mph, an American carrier could travel ~6 miles in that time. I don’t know much about trajectories over such ranges but I wonder whether they would be flat enough to avoid exo-atmospheric flight which might render traditional BMD unusable against them.

    On the issue of target acquisition, I wonder if they are to be used in conjunction with China’s fleet of diesel-electric submarines. Against the ASW capabilities of a carrier battle group how long would a conventional submarine last after firing its first torpedo? Not very long, perhaps a few minutes? However, the Chinese have shown that one of their submarines can surface close to an American aircraft carrier so if they can avoid firing torpedoes then they can avoid detection and survive a lot longer. So the DF-21D could be a replacement for conventional torpedoes.

    Finally, a war over Taiwan will not be a life or death fight for America. So, the Chinese just have to make an American intervention in that war very expensive for the Americans. With a unit cost of $4.5 billion and a crew (ship and air wings) of over 5,000, losing a carrier would be expensive so how willing would America be to commit several carriers to such a fight? Rationally, if they thought that they would would lose several aircraft carriers to missile with a unit cost of a few million dollars, I would suggest very unlikely. In fact, the missile doesn’t really have to work as long as the US military think that it most probably might. And it has to have a conventional warhead to avoid escalating the conflict to a nuclear war.

  7. Allen Thomson (History)

    > So I’d expect to see development of a Chinese RORSAT like satellite…

    How about an EORSAT (or Parcae)? C.f. Yaogan Weixing 9.

    It might be worthwhile to review what is known about the SS-N-13 and maybe the SS-N-17. Since the warheads of those were probably nuclear, the accuracy requirements would be less stringent, but some useful insights into the ASBM problem might be obtained.

  8. RAJ47 (History)

    China has already got a very effective OTH radar system in place to track the carriers. The Yuanwang series of ships could be used to track the DF-21D. The terminal guidance seems to be very easy using either thrusters or fins or a combination of both.

  9. jeannick (History)

    A surfaced sub within close proximity of a carrier escort screen would have a very problematic survival time,
    an analysis of the flight vectors of the U.S. planes would narrow down the area .

    as for going nuclear , that would be highly unlikely to said the least,

  10. patrsup (History)

    Good thoughts and comments to this point. I would just throw out a thought that the US would probably like to take the missile in the boost phase. This has been done in a closed country fairly recently and was portrayed as a mechanical malfunction with the US being closed lipped about it. Remember if we can get it in the boost phase – we only need to kill the bus to get all the warheads/vehicles at once.

  11. john doe (History)

    your article is based on assumption that flight is ballistic, Mark Stokes 9/14/09 article from ‘Project 2049 Institute’ quoting from the Chinese suggested a power flight and the missile shall cruise between exo/endo layer in mid-course. The RV may be a hypersonic cruise missile coming in at low altitude during end game to avoid Aegis & SM3 defense, CWIS shall be the last defense. My doubt is that hypersonic cruise missile needs large control surface. Deployable fins may not be stable & fixed fins too big for DF21 payload envelope. Since US has capability to detect moving surface target, do not under-estimate PRC’s capability.

  12. Barry (History)

    Disclaimer: My field of specialization has nothing to do with ASBMs, but your article looked interesting.

    “Of shoes and ships and sealing wax …” (Alice Through the Looking-Glass)

    Well, not so much about shoes and sealing wax, but more about ships; specifically, US CSGs (carrier strike groups) and the Chinese DF-21D ASBM (anti-ship ballistic missile), which have recently been in the news.

    We want to defend a CSG against the DF-21D. We assume that we will attack the ASBM when it is around 50 km from its target (and moving at close to 10 times the speed of
    sound), but due to various reasons nuclear weapons cannot be used.

    One possibility is to use a missile that (when it explodes) generates a sufficiently strong shock wave to disrupt the flight path of the ASBM. (If it could also explode the ASBM, so much the better, but at the very least it should disrupt the flight path.) Given what we
    know about the ASBM, it should be possible to calculate the strength of the required shock wave, and hence the type and amount of explosive needed for the missile. (Of
    course, more than one missile could be used.)

    A second possibility for disrupting the flight path is to significantly change the air density in front of the ASBM. One could either drastically cool or drastically warm the air in front of the ASBM. Again, given what we know about the ASBM, it should be possible to calculate how much air, and how much the air temperature, needs to be changed, in order to significantly change its flight path. There are many ways to change air temperature, depending on whether one wants to cool it or warm it. (However, unlike the first suggestion, I do not know whether this suggestion would work.)

    A third possibility for disrupting the flight path is to place obstacles head-on along the way; viz., numerous missiles that also explode. (If they also explode the ASBM, so much the better.) Given what we know about the ASBM, it should be possible to calculate the total weight of the missiles needed and how much explosive.

    A fourth possibility for disrupting the flight path is by attaching something to the ASBM. One way to accomplish this is by having a ‘sticky missile’ hit head-on with the
    ASBM; that is, a missile containing a very sticky substance that will stick even to an object traveling at 10 times the speed of sound. If possible, the sticky missile should be designed so that whatever gets stuck to the ASBM, gets stuck to it asymmetrically.

    Along the lines of attaching something, use missiles that hit head-on with the ASBM, puncture its surface, and attach to it objects that destroy the stream-lined flight path.

    The ASBM’s shell would best not be magnetically conducting. But if it is magnetically conducting, use a missile that (explodes and) releases very strong magnets that attach themselves to the ASBM and whose shapes destroy the stream-lined flight path.

    Finally, a word about using undersea ASBMs. Plant them in areas where you know the CSG is likely to congregate, When the CSG is there (as can be told by radar), release them from their moorings. Alternatively, calculate how great the magnetic field would be when the CSG is there; when the magnetic field reached this value, release the ASBMs from their moorings. In either case, the ASBMs should be designed to float up toward the greatest magnetic field. Also in either case, the ASBMs can be ‘neutralized’ by using a ‘false aircraft carrier’ that generates a very large magnetic field. BTW, some concept of a ‘false aircraft carrier’ might also be used to deflect an air-borne ASBM from the real thing.

  13. Matthew Hoey (History)

    Great job with this piece, Geoffrey.

    We will all soon find out if the technological claims are exaggerated regarding India’s Agni-5, which is estimated to be capable of hitting all of China, nearly all of Russia and Eastern Europe. The flight test is scheduled for 2011. India claims that the range will be 5000–6000 km. It has also been reported that the Agni-5 will carry multiple warheads (up to 10) and will contain countermeasures against missile defense systems. I would like to see some commentary by the arms control community regarding India getting a free pass on such launch technology. It is noteworthy that in comparison to the attention being paid to Iran, the DPRK and China, the arms control community is virtually silent regarding India’s track record of defiance in the face of international arms control initiatives, its history of missile technology proliferation and its role in helping to provoke China to step up its game. More importantly, there is little criticism about the rapid removal of hurdles that were put in place by the United States after India’s five nuclear tests in 1998. The last of these hurdles, for DRDO (which is responsible for the Agni-5 program) in particular, are expected to be a primary topic of discussion between Singh and Obama in November. India’s Agni-5 will significantly undermine China’s deterrent capability – and if the 2011 launch test goes as planned, the China military buildup will surely accelerate as a result.

  14. John Schilling (History)

    The US Pershing II is certainly proof of concept for the general idea of radar+aerodynamic terminal guidance of IRBM RVs, with cutting-edge 1970s American technology. 21st century China ought to be able to match that, and the differences between small land targets vs. large maneuvering naval targets do not seem overwhelming. IR vs. radar guidance is a possibility, but George Herbert is correct in noting that you probably do need terminal guidance of some sort – and with an IRBM’s flight time, you might be able to make do with only terminal guidance.

    Certainly the DF-21D would be vulnerable to interception by SM2/3 missiles, and there’s not much that can be done about that – Aegis is not narrowly optimized against ballistic RVs, the US Navy has long had a keen interest in dealing with the full range of Things Moving Very Fast Towards Our Aircraft Carriers, and when “very fast” crosses into the hypersonic range you’ve pretty much ruled
    out stealth or swarms of decoys as your way of slipping past an adversary’s defenses. A few credible but heavy decoys shoehorned into a DF-21D’s limited payload, maybe.

    Overwhelming them with numbers, maybe. An Aegis cruiser carrys 128 launch cells, but probably only a dozen will hold SM-3s, and there are only four fire-control radars for the SM-2s (only needed during the last few seconds of flight, but there are only a few seconds available for an SM-2 intercept). Pk will be somewhat less than 1.0, so if the Chinese are willing to salvo a dozen or so SS-21Ds they’d have a fair shot of hitting a carrier.

    Or a cruiser or one of the larger Marine amphibious assault ships; I disagree that only CVNs are worthy targets of such a missile. For that matter, the limited SM-3 loadouts of the Aegis cruisers/destroyers themselves might be a “target”. China’s minimal strategic deterrent has to have them concerned about losing credibility in the face of effective missile defenses. To the extent that the US’s effective missile defense capability comes from forward-deployed Aegis/SM3 systems, China can wear down the defense (restoring strategic deterrent credibility) by firing a few salvoes of conventional, intratheatre weapons at targets the US cannot afford to sacrifice.

  15. Seb (History)

    RE Andy’s comment about submunitions, this is something I’ve been wondering about for a while too.

    Appologies if I have made some mistakes here, this is not my field, so please jump in an correct me.

    Suppose the missile consisted of a bus and a bunch of kinetic penetrators.

    I read the DF-21 has a payload of 2000kg, I assume (perhaps wrongly) it could carry something like 1000kg worth of kinetic penetrators + a bus, radar, whatever.

    If we take a 120mm anti tank round as a model, 2cm by 50cm rod of DU at 19gcm^3, 3kg per dart, so 330 darts.

    How many “anti tank rounds” would you have to put into a flight deck to make carrier operations impossible without major repairs, and score a mission kill? I imagine not that many. I’m going to say 20 for the hell of it but perhaps this is stupidly optimistic. That makes a requirement of 1 penetrator every 1300 square meters, so the missile can target a circle radius 370 meters, thereabouts.

    Perhaps you don’t want something optimised for penetration, perhaps you want lots of golf ball sized lumps, and you get a lot more penetrators, but I suppose that depends a lot on whether the penetrators aren’t going to be horribly spread out and what velocity various shapes end up with at sea level after re-entry.

    Could you not then release the penetrators at a higher altitude to make SM3 interception harder (less time to kill the bus, and nothing much you can do after the submunitions separate) and trade required accuracy for area of effect?

    Also, this would have the added benefit of putting a carrier out of action and achieving the same objective (keeping the US carrier groups at a certain distance) without actually sinking a carrier which might escalate any conflict.

  16. GI Zhou (History)

    Great article Geoffrey. There are two pieces missing however. Firstly, if the US Navy was expecting an attack there would be more than one CBG, most likely three, in the area and a greater number of than in peacetime of accompanying escorts including submarines. Secondly,
    and this would weigh on PLA planners minds, what would happen if the missile is launched and the US Navy retaliates with launch on warning rules of engagement?

    The accompanying AEGIS cruisers and destroyers could unleash launch a massive wave of cruise misiles at Chinese targets and the attack submarines that accompany CBGs would make life hazardous for any Chinese submarines or surface vessels nearby. Shanghai can be easily bottled up from the sea by a few well placed torpedoes.

  17. fin (History)

    Thank you for this interesting and thoughtful post. Here’s my two cents on this (as most DF-21D talk, it is conjured from my limited technical insights and my colorful fantasy)
    I don’t understand why everybody speculating about the DF-21D’s guidance and control assets assumes that it is intended to slam into a carrier at blazing speeds. People hear the word ASBM and imagine a comet splitting the USS Stennis in half. So much talk of how the RV could see through the plasma sheet, in what height it will make its final targeting adjustments and how mid-course corrections will be transmitted.
    What if there’s no need for any of this? In my view, the most technically feasible (and therefore likely) approach is one of independent guided submunitions, released from a strongly decelerated RV at an altitude from where they can glide anywhere within the aforementioned 13km radius of error. A miniature version of this idea is reality: Tin can-sized, IR-guided submunitions, released from a parachute-retarded CBU-97, can independently target a moving tank. Why shouldn’t a 250kg bomb, equipped with IR/radar guidance and released at 30km, be able to independently locate and engage a large surface combatant? The readily deployed DF-21C has a stated payload of 2000kg. Since that is room enough for multiple warheads, a reliable mission kill would be possible despite the decreased speed of engagement. As for the missile itself, inertial guidance toward the last known location of the carrier at launch time (provided by OTH) would be sufficient. No dedicated satellites, no target illumination, no plasma sheet penetrating sensors, no thruster control, no taget updates. No new stuff. That would explain why the ominous “Chinese Internet” claims that the Delta is nearing deployment.

  18. jeannick (History)

    An optical acquisition and identification system should be doable ,since it is passive it would make a lot of countermeasure obsolete , it could use several bands from the IR to the visual and provide a good final targeting solution

  19. John Schilling (History)

    It’s technically feasible to deploy slow-moving submunitions from a decelerated IRBM bus, but it’s not clear what this would accomplish if the target were a large USN warship. Such an attack would give the target opportunity to deploy a full multilayer defense, SM3 through SM2, ESSM, RAM, and even Phalanx, with multiple opportunities for shoot-look-shoot reengagement, and would represent almost precisely the sort of attack the United States Navy has been planning (arguably hoping) for since the 1970s. Dozens of large, merely supersonic munitions at high altitude – with a stated range of 3000 km, the Chinese could take their first shot at a CVBG just west of the Marianas, and they can certainly paint turkey logos on the submunitions.

    Also, note that US aircraft carriers are a lot tougher to even mission-kill that many people give them credit for. Unless you’re particularly fortunate in the timing (i.e. hit while a major strike is gearing up on deck), a couple of 250kg bombs are not going to do the job. This really does call for the full payload of a DF-21, the faster the better.

    If the plan is simply to deliver lots of 250kg smart bombs to the vicinity of a CVBG, a single H-6 bomber could do the job of three or four DF-21s, and the Chinese have plenty of H-6s already. They’ve even got stand-off cruise missiles if they don’t want the bomber itself to get too close. If the plan is for any great number of these munitions to actually reach their target, they really do need to be moving blindly fast throughout the process.

  20. taiwanlink (History)

    Excellent write up, Geoff, and great comments as well. The ASBM issue deserves solid, sober technical analysis and this dialogue certainly qualifies as such. In addition to the Project 2049 piece, Eric Hagt and Matthew Durnin published a good technical overview in the Naval War College Review last Fall. Andrew Erickson from the Naval War College has done some excellent work on the issue as well.

    One of the problems in the past, particularly within the US Navy community, has been a tendency to either:

    1. Discount the technical feasibility of a missile being able to hit moving target at sea at a range of 2000 kilometers;

    2. That it can be done, but Chinese engineers are incapable of doing so;

    3. Possible, but carrier battle groups with AEGIS-based SM-3 and other ship-borne defenses are capable of handling incoming missiles (usually citing the Soviets and how we’ve been through hyped-up threats to carriers before);

    4. Missile is possible, but supporting sensor network would be insufficient to support the missile and therefore not a challenge;

    5. Definite and imminent, and no defenses exist.

    What Geoff and commentators here have done very well is to at least think through some of the technical issues. Geoff’s conclusion seems quite reasonable. An ASBM capability appears technically challenging but feasible. As an interesting side note, DARPA seemed to have been asking the same question last year when it put out an RFP for a technical feasibility study on a missile that seems to have very similar capabilities as an ASBM.

    And if it is possible to design, develop, and produce a missile capable of penetrating missile defenses and striking moving targets at sea at ranges above 2000 kilometers, then could Chinese engineers succeed? Of course they could. For a Bubba’s point of view, if Chinese aerospace engineers are capable of hitting an object the size of a Volkswagon flying at Mach 25, then why wouldn’t they be capable of hitting a target on the ocean coasting along at 35 knots?

    At least some of the technology that has been developed for a KKV since 1986 could be applied toward a guidance, navigation, and control system to go against a surface target. Regardless, Chinese engineers deserve respect, and would be particularly motivated if there was alot of funding thrown at the engineering problem.

    One type of guidance (or navigation) that seems to be getting alot of attention is missile-borne synthetic aperture radar (SAR). However, even Chinese engineers in BBS discussions admit this is really hard, ostensibly due to the need to maintain a steady flight path while acquiring the target, and perhaps even fly by it, then maneuver back around for the terminal phase. As an aside, there does appear to be a good base of literature that indicates some type of hybrid, restartable engine/motor is being tested.

    On the third issue, China’s aerospace industry has been quite aware of U.S. missile defense programs since SDI. Technical writings seem to demonstrate a modest degree of confidence in defeating PAC-3, SM-3, THAAD, and other interceptors. For SM-3, it seems like the solution being looked at is to avoid shot opportunities by going with a depressed trajectory, or maybe even a boost-glide capability that bounces in and out of the atmosphere. The father figure of China’s missile and space program, Qian Xuesen, is said to have been an advocate for developing a Sanger-like flight vehicle.

    Besides, haven’t there been assurances made to Russia that U.S. missile defense programs, such as SM-3, are focused on lower end threats, such as those developed by North Korea and Iran? If so, then it seems like the SM-3 (or even PAC-3 in the case of SRBMs) would have a very difficult time against Chinese ballistic missiles.

    After all, China has the most technologically sophisticated and largest arsenal of ballistic missiles with ranges between 500-5500 kilometers in the world. Of course, that’s because the U.S. and former Soviet Union destroyed land-based missiles within these ranges under the INF Treaty!

    The fourth point — lack of a sensor network — seems to assume that Chinese planners and engineers aren’t capable enough to figure out the sensor/cueing issue. One of the arguments commonly posited is that they don’t seem to have the space-based ISR network needed for persistent surveillance of the maritime environment. Or if they did, satellites in LEO are vulnerable. Or that the skywave HF over the horizon (OTH) wouldn’t offer sufficient resolution of targets at ranges beyond 2000 kilometers.

    A counterargument could be that external cueing requirements could be dependent upon how autonomous the missile is in terms of on-board sensors. In addition, Chinese aerospace engineers seem to be doing alot of work on flight vehicles that operate in the “near space” domain, that is, the realm between 20 and 100 kilometers. There certainly are challenges associated with developing and deploying high altitude airships operating in this realm. But if I were sitting in Beijing, R&D investment into near space flight vehicles makes alot of sense.

    Finally, on the last point, even if Chinese aerospace engineers are able to successfully test and deploy a viable ASBM, it doesn’t necessarily mean the end of aircraft carriers and life as we know it. If an ASBM does indeed negate the ability of SM-3 to defend battle groups, it probably would mean a carrier would operate out of range of the ASBM. So instead of F/A-18s conducting strike missions, it means other capabilities instead. Boost or ascent phase interceptors certainly make sense to catch a missile when it’s most vulnerable, but interceptors would need to be deployed in hardened facilities on land in Japan (or Taiwan for that matter), or perhaps from subs (hard to do).

    Along these lines, one of the most significant challenges stemming from a proven ASBM capability would not necessarily be operational in nature. An argument could be made that deployment of systems like an ASBM, or other extended range precision strike capabilities, may incentivize neighbors, and the US of course, to develop similar capabilities. An ASBM and growth in China’s conventional MRBM infrastructure, would likely encourage others in the region to increase investment into stand off strike capabilities from either hardened positions if operating inside the threat envelope; or if outside the envelope with systems such as those covered under the Prompt Global Strike program.

    One should also remember that senior Russian officials have threatened to withdraw from the INF Treaty unless similar constraints were placed on unnamed neighbors with growing medium and intermediate range ballistic and ground launched cruise missile arsenals. There’s only one country that really fits this description, and it’s not North Korea, Iran, or India. China’s expansion of its conventionally-capable ballistic and ground launched cruise missile force does seem like it could undermine the INF Treaty over time.

    Starting to ramble, but kudos to Geoff and others here for an excellent discussion!

  21. george (History)

    this weapon does not exist and possible. if the American can’t make it, no other country can. don’t worry, sail your super size carrier anywhere near China as you please.

  22. Dan (History)

    This is a bit off topic, but you all seem like experts. I’ve wondered since the Exocets were used in the Falklands why our aircraft carrier groups are not obsolete given modern missile technology.

    • ajay (History)

      Dan: because modern navies are confident in their ability to defeat Exocet attacks through a three-layered defence of fighter aircraft patrols (to knock down the attacking aircraft before they launch their Exocets), escort destroyers firing anti-missile missiles (to knock down the missiles at long range) and close-in weapon systems (rapid-firing radar-aimed guns to knock down the missiles just before they hit).

      The outermost layer is the only one that’s ever been properly tested, though. There’s only one example in history of a real escort hitting a real missile with an anti-missile missile, and no examples of a close-in weapon system working in combat.

  23. Bob (History)

    Interesting posting and subsequent discussion.

    As a note the B in ASBM stands for ‘Ballistic’ meaning that the missile will have a ballistic or parabolic flight profile reaching, at a minimum, the lower edges of space.

    Any powered (air or sea-borne) munition will be definition be a ASM (even with a terminal pop-up phase) or a torpedo (even the CAPTOR mine concept discussed by Barry in his ‘undersea ASBM’ scenario.

    All of these scenarios require different defensive profiles and systems. Obviously, the ASBM and ASM defense missions have a significant degree of overlap.

    With regards to sub-munitions the constraints there will be:
    1. Size – large enough to generate enough damage for mission-kill (outright destruction would be doubtful).
    2. Release altitude – the higher up the munition, and the larger (see note #1) the easier it will be to defend against. Altitude=equals kinetic energy for mission-kill and maneuvering.

    Also, do not underestimate the ability of a CVN to maneuver and get up to speed. One might be surprised at how fast one of these babies can move at Emergency Flank!

  24. Chris (History)

    I don’t know much about the whole topic, but if it is that hard to figure out the position of the carrier, why don’t fire one missile with some kind of sensor payload and another with some destructive payload a minute later?

    The sensor payload could contain a good number of independent target tracking devices and could provide the real time position information to the second missile which could be fully loaded with destructive stuff…

  25. Dan (History)

    Could someone who knows a lot more about lasers that I do speculate on the required laser power to make the aforementioned terminal guidance system unhappy/ineffective. It seems that 10 kw laser power at a minimum is currently doable. Is this enough to disable terminal guidance? That is a much easier thing than actually frying a missile fired at a stationary target.

    • JR (History)

      @Dan, the power required is probably doable, but getting the beam to stick to the target with enough power and dwell time is the challenge.

      Burnout velocity for a 2,000-km system is about 2km/s (using gross rule of thumb: 1km/s vel for each 1,000km of range). So before it hits thick atmosphere on descent — say, 50km altitude — it’s going to be moving that quickly in a ballistic trajectory. You either need to dwell on the target during the long exoatmospheric descent from apogee to reentry, and deal with shooting through 100km of atmosphere as well as the inverse-square law robbing you of your power, or you need to wait until it’s reentering, which introduces a whole other raft of challenges.

      Once it reenters, even if it’s unguided, the deceleration is going to make it bloody difficult to keep a beam tracking on the RV. The axial acceleration curve is going to spike somewhere well north of 30 Gs (maybe even 100 Gs?), and it’s not going to be a constant acceleration either. Now add the hypothetical terminal guidance, and realize that the RV is probably trying to induce lateral acceleration as well. All of this is happening in the Mach 7 – Mach 3 regime… it’s a tracking nightmare, and you’re talking about trying to bulls-eye the guidance system. You might have better luck aiming for the center of mass and overloading the thermal protection system; it’s designed to survive reentry, but if you can add more heat than it can slough off, perhaps you can cook a hole in the shielding and let atmospheric friction do the work.

      If there is terminal guidance, even if the guidance system is getting good data, the control system will not be able to recover from having a hole burned into the RV. That’s where I’d put my terawatt laser if I had one.

  26. muttling (History)

    A very interesting read.

    Two commments….

    1 – What about a space based launch platform like the old Russian Polyus which failed on launch? It seems to me like a space based launch platform would greatly reduce the complications that have been described.

    I know that there are a lot of treaty issues with weaponizing space, but it would seem to me that they could deploy a small number of some sattelites that appear to have other purposes but are actually carrier killers and no one would know until they attacked.

    2 – @Dan,

    Exocets aren’t the threat to our carriers that you think. You must first get an aircraft close enough to launch one (not easy.) Then your pilot must target the correct ship (not as easy as you might think.) Carriers don’t sail by themselves, they run with a pretty stiff escort to protect them. They have their own Phalanx systems along with the Phalanx systems of their escorts. Even IF an Exocet gets through, it would do some damage but it would take a BUNCH to take out a carrier. These aren’t the smaller, aluminum hull vessels that were roasted in the Falklands.

    • Andrew Tubbiolo (History)

      @muttling An orbital platform almost guarantees that you’d need a large number of stations. The Earth rotates under a satellites orbital plane and you may only have 4 or so passes per day that would allow you to take a shot at a CVN. Think of the Iridium satellite communications system that uses over 60 satellites in order to maintain coverage over the planet. The nature of the subject would require this many satellites for 1 customer or millions. Same with attacking ground target from orbit. Ground based platforms on hair trigger alert are cheaper, easier to make, and more effective.

  27. JR (History)

    Regarding infrared sensor aiming, when I was in the USN 30 years ago, my WW-II vintage ship had equipment capable of covering the entire ship with a deluge of water, to defend against fallout and chemical attack. [Hoping I’m not divulging top secret stuff here!] We’re talking about facilities capable of pumping many thousands of gallons of water almost instantly here.

    Surely such defensive equipment is still designed into our fleet?

    Wouldn’t surrounding a ship with a shower of spray prevent an IR sensor from detecting that ship now surrounded by a cooling shower of sea water that started at the same temperature as the surrounding sea, but which is now cooler by evaporation?

    I imagine it might even affect radar, I know rain has a effect on weather radar and satellite communications.

  28. Andy (History)

    Well have to drop my cents on a point that has been forgotten here: cooperative engagement capability.

    Since the more AEGIS Ships you have in one group the better and more accurate is your tracking and terminal guidance of the interceptor. Means one AEGIS Ships barely has a chance against a sophisticated Anti-Ship missile (Sizzler, Brahmos, DF-21D, maybe even against an exocet or harpoon) But you can track and illumintate the target more accurate especially a High-G maneuvering missile in terminal flight if you use x>1 AEGIS ship, above that cooperative engagement capability gives you greater range to detect the target (battlespace awareness).

    Some of you pointed out the number of cells a Tico has. That does not matter in a battle-group! AEGIS selects the right weapon from the right ship in the best shooting position automatically if incoming is detected. (remember Iranian Flight shot down by SM-2 (or 1?))

    compared to the russian AD Systems the US relies on layered defense. from outer to inner: SM-3, SM-6 (Im a fan of this one already), SM-2 RIM-66M Block IIIB, ESSM, SeaRAM, CIWS. On land based you can put THAAD between SM-6 and SM-2 Block IIIB and PAC-3 somewhere around ESSM and PAC-2 (by trend Anti Aircraft) somewhere around RIM-66M.

    As for the vast number of incoming Anti Ship missile keep in mind that the ESSM (an extremely sophisticated interceptor, used as the primary interceptor by many american-buying navies around the world and that means something) can be quadpacked into the MK41. Given the fact that a DDG-100 (i.e.) has just 10 cells for ESSM makes 40 missiles you can fire at an incoming now add the cooperative engagement capability.

    I at this point highly doubt that a Carrier Strike Group with 2 Ticos and 3 Burkes maybe even a SanAntonio armed with seaRam and the carrier itself is an easy target for a DF-21D.

    almost forgot: the E-2C and soon the E-2D with AESA can be integrated into the cooperative engagement capability.

    This makes our carriers the best defended airfields in the world! And those are facts and not paper tigers!

    BTW: since I am a fan the SM-6 is close to IOC. And do not forget the SM-2 RIM-66M Block IIIB has a IR seeker and a maneuvering upgrade (I assume it to be thrust vectoring correct me if you have better information here)

    thanks for reading.

  29. Walt (History)

    How hard would it be to spoof the terminal guidance sensors. Would flare launching systems on all the ships in a battle group create sufficient confusion in the sensor to dramatically reduce its accuracy. Same question for chaff launchers. At the Mach 10 or higher speeds of the presumed ASBM the sensors might not have the time necessary to discriminate between decoys (either thermal or radar) and would fail to find the target.

    Putting that as the inner layer in a layered defense (under the SM-2’s and 3’s) might reduce the effectiveness of the system to a point where it wouldn’t justify the risk inherent in the attack itself.

    Make sense?

  30. george (History)

    i have read a Chinese source some years ago discussing how to sink an air craft carrier. they suggested they will fire 1000 missiles at the same time to target one target that is air aircraft carrier. if that is the case would there be enough anti missiles to knock down 1000 missiles at the same time. that is why they are going to mass producing the df 21d after further field test.

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