Point Defence in Space Combat

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Anti missile missile missile missile missile missile. -Quote of me explaining the tactics in my sci fi setting

One very cool detail in The Expanse is that the PDC's have their own thrusters to counteract the effect of the recoil on the ship.

I'm probably not the first to mention the Honorverse here, but I've always thought the type of layered defense it portrays worked well. Countermissiles for extended range interception, point defense laser clusters for close-in defense, and decoys, jamming, and ECM for additional defense. Honorverse attack missiles are mentioned as maneuvering to evade defensive fire too and supported by penetration aids or "penaids" to defeat defensive fire.

Homeworld introduced a cool concept such as Drone Frigates. These ships would launch a plethora of small gun drones that would form a sphere around the ship. The drones' goal was to destroy fighters and serve as point defense, and because they were free from the ship, the drones could aim anywhere without being attached to the ship.

I'd say that space combat is a setting in which Flak makes even more sense. Imagine thousands of pieces of Tungsten flying infinitely across all directions

8:50 Thruster enabled flight. It is just so mesmerizing to see.

It’s implied that the missiles in The Expanse do fly evasion patterns. Holden mentions it in S5.

This morning during commute, I had the urge to listen to X-COM 2's Ready for battle theme. Wasn't expecting to hear it in a 10 minute video the same day.

Nebulous: Fleet Command really gets that emphasis of having a good PD net; especially for capital ships and their escorts. Having a mix of 20mm rotary cannons, flak cannons, point defense lasers and even small burst-fire railguns is essential. In addition, you can even use small missiles that explode into fragments for swarms and such.

In the Expanse, there are shotgun PDCs, used by Belter ships at times.

Most of the footage we see in The Expanse of missiles has them essentially in the initial boost phase (generating a base vector towards the target volume after launch) or in terminal acquisition*, wherein they have to cut any jinking and reserve any RCS in case they need to generate a radical delta-v in response to their target's evasion attempts. Yes, this makes them more predictable targets for point defence fire, but given the geometry and relative velocity at that stage in flight, it's better to have the ability to maneuvre to generate a hit than to overshoot and have to kill their own velocity and build up an overtake in the target again. Also, if their trajectory has stabilised on an intercept, and they get hit by a CIWS, there's still a chance their shrapnel cone will intersect the target and cause some damage, but if they are jinking around when hit, there's a greater chance the target will not be in the path of any one piece of shrapnel (since there's a lateral component to the missile's moment which will influence the expanding cloud of shrapnel that used to be a missile, and no guaranteed that the missile will be hit at a complementary portion of its own evasive maneuvres). Granted, this is speculation on my part, but I believe it justified (or at least justifiable). *Ok, we do also see missiles in a ballistic coast phase. It is, after all, how the OPA got its hands on those excellent strategic weapons. We don't see any on screen in a mid-flight jink phase though, you're right.

Mass Effect had a good balance as the main weapons were KEWs but the PDWs were DEWs. Regardless this video really demonstrates that every offense has a defense.

The British Sea Dart was originally designed as an area defence missile with little or no point defence capability against incoming anti-ship missiles. These limitations became a big deal in the 1982 Falklands War. After that, the system was quietly upgraded in many ways, making the Missouri Silkworm kill possible. It has to be pointed out though, that a Silkworm is a BIG, slow missile: much bigger than an Exocet and much slower than a Kh-31. The first missile in the world specifically designed to shoot down anti-ship missiles was the British Seawolf, which debuted in the Falklands, but only on three ships and never got a chance to show that capability. Early versions had conventional launchers but later ones had vertical launch with a tandem, thrust-vectoring booster that gave them a 360 degree arc of fire. Seawolf is now being replaced by SeaCeptor, which is also vertically launched but has an active seeker, so the number of targets that can be engaged simultaneously isn't limited by the number of fire-control radars on the ship.

Everyone knows Casaba howitzers are the best point defense weapons, because why wouldn't you want to ride into battle surrounded by a halo of close proximity nuclear detonations? Rhetorical question, of course you want to do that!

One of my favorite examples of a ship using all three PDW types you mentioned was the SDF-1 Macross from the Macross franchise. 100 point defense gun turrets split between kinetic and energy based, plus 24 point defense missile turrets. This was in addition to over 500 Destroid type mecha which could be used in a mobile point defense/anti-ship role.

I usually write my point defence in four layers : ECM, counter missiles, direct fire point defence and terminal interception. ECM is the general electronic warfare side, misleading missiles, sending them after decoys, with the missiles doing the same on their end, trying to create ghosts or dodge around, ect. Counter missiles are for midcourse interception, usually by using nukes to create a cloud of plasma, either as flak (preventing the need for a direct kinetic hit to take out a missile, which are hard to produce thanks to ECM), or as an additive to electronic warfare, creating a flash of energy and a wall of cooling plasma that confuses sensors, which ships can work around far more easily than the limited sensors onboard missiles. Direct fire point defence is usually close in, although some variants are longer ranged, and finally most of the missiles in my novels have a 'terminal attack phase', where they burn out their sensors trying to punch through the cloud of ECM and find where the ship is exactly to hit it (usually with bomb pumped laser warheads), and become giant beacons of light, and all of their own ECM is stripped in the process. The terminal phase sometimes has its own dedicated point defence systems, made for very short range and with more primitive sensor systems, but most of the time the normal point defence weapons are simply retasked in a desperate bid to take out the last of the enemy salvo before they hit.

Jinking a missile at a fraction of the speed of light comes with its own mathematical issues, not least in accurately detecting the incoming interceptor projectile closing at approaching double that fraction, just as the real target advances or even retreats. In The Expanse, ships and missiles use similar engine types and move in similar speed ranges to catch ships, they can just accelerate or turn faster, so referring to them as torpedoes is more appropriate as they can be outrun if detected early enough, like early torpedo types. Modern anti-ship missiles move at ten times the speed of ships and the difference doesn’t seem to be that big in The Expanse.

Phased array laser weapons will be difficult, since you're wasting a lot of energy on the unfocused leftovers from the phasing. Only a small % of the energy is contained in the head, which is also expanding rather quickly. A better use for that tech would be to have it provide miniscule adjustments to optimise the beam within the laser's already existing divergence bounds.

Slightly disappointed that the interceptors in Babylon 5 weren't mentioned. Unless I missed it. Who can forget the iconic phrase "Reset forward interceptors for long range dispersion fire!"