Ballistic missile defence and the Type 45 Destroyer

The purpose of this article is to examine the options the Royal Navy has for improving the BMD (Ballistic Missile Defence) capabilities of the Type 45 Destroyer.

This article was submitted by Ethan and is an opinion piece. Please note that the opinion of the author may not necessarily reflect that of the UK Defence Journal.

This article is the opinion of the author and not necessarily that of the UK Defence Journal. If you would like to submit your own article on this topic or any other, please see our submission guidelines.

With a primary role of AAW (Anti-Air Warfare) and long-range defence of the fleet from aerial threats, the Type 45 is the most suited class of surface warships to receive a BMD-focused upgrade. 

Background

While ballistic missiles have existed for over 50 years, the prevalence of anti-ship ballistic missiles has increased dramatically within the past decade with both Russia and China introducing new anti-ship capable ballistic missiles.

To clarify, the focus of this article is not to analyse the potential of procuring ship-based defences against ICBMs (Intercontinental Ballistic Missiles), as is the purpose of US Arleigh-Burke class ships based in Rota, Spain. This task is somewhat insurmountable for even land-based systems and the US ICBM defence presence remains a token force of deterrence at best. Regardless, these ICBMs are impractical in targeting surface ships and don’t pose the same class of threat as anti-ship MRBMs (Medium Range Ballistic Missiles) recently fielded by China and Russia.

China has begun to employ batteries of the Dong-Feng 21D ballistic missile which can threaten surface ships up to 1500km away from a coast. Because of this capability (and a certain amount of geopolitical rivalry), the DF-21D has often been touted as a ‘carrier-killer’ missile to deter American carrier strike groups in the Asia-Pacific region.

The UK’s primary military presence in the Asia-Pacific region will be primarily through intermittent CSG (Carrier Strike Group) deployments, the first of which will be underway in a few months time. In a hypothetical war against China in said region, due to the <1000km unrefueled combat radius of the CSG’s primary strike aircraft, the F35B Lightning II, a UK CSG will be limited to distances within the DF-21D’s 1500km reach.

This is exemplified when it is known that RAF F35Bs will not possess long-range standoff weapons until at least 2024. A CSG will have little to no luxury of simply ‘staying out of harm’s way’, should it intend to conduct deep strike missions against Chinese land targets.

Although it is acknowledged that the ability to lob a projectile long distances is one small step in a very large kill-chain, it is logical for the Royal Navy to invest in a hard-kill BMD capability.

Notable previous events

As has been previously reported by the UK Defence Journal, the UK has expressed interest in procuring existing BMD-capable missiles (Aster Block 1 NT in particular). However, this potential order was suggested in tandem with a French purchase of Brimstone missiles, suggesting this order had greater concerns about supporting local industry (Aster B1 NT has very little industrial links to the UK workforce) than of improving the UK’s BMD capability.

BMD focused exercises have also been conducted with a Type 45 Destroyer in 2013, using its SAMPSON radar to locate and track two ballistic targets and its Command and Control infrastructure to provide real-time estimates of the launch and impact points of the targets.

The 2015 Strategic Defence and Security Review had also expressed intent to ‘investigate further the potential for a BMD capability in the Type 45 Destroyer’.

SAMPSON MFR

SAMPSON MFR (Multi-Function Radar) is the Type 45’s primary search-and-track and fire control radar. It consists of two back to back AESA (Active Electronically Scanned Array) radar panels which rotate at 30rpm to provide near constant 360 degree coverage of the air. SAMPSON’s primary function is to provide air search and track against incoming threats, whilst simultaneously guiding intercepting Aster 15 and 30 missiles to their targets during their mid courses.

BAE has shown intent to give SAMPSON a BMD-focused upgrade in 2024, however very little is known about the program. It could be speculated that this upgrade will introduce a third planar array, pointing directly upwards and giving better coverage of the ship’s zenith from ballistic threats with a steep trajectory. 

During the aforementioned ballistic missile tracking tests of 2013, SAMPSON trialled an experimental software upgrade to improve SAMPSON’s performance against ballistic threats. This software was reported to have worked ‘better than expected’ and so it is feasible that a development of this software could be installed as a bare-minimum upgrade to improve tracking performance.

It is interesting to note that SAMPSON has not received any major upgrades since it first entered service on HMS Daring.

SMART-L/S1850M

S1850M is the second major radar system onboard the Type 45 Destroyer. It is a long-range air search and track radar with reported ranges (against aircraft-sized objects) out to 400km (provided the target is at an altitude high enough to be seen over the horizon at such a distance). S1850M is a development of the Thales SMART-L radar, sharing the same front-end PESA (Passive Electronically Scanned Array) radar panel and using some back-end processing components from the Marconi Martello S723 radar.

While the S1850M and SMART-L systems have already shown limited ballistic missile tracking capability, Thales Netherlands have continued development of the SMART-L system with the SMART-L-EWC (Early Warning Capability), later referred to as SMART-L-MM (Multi-Mission). SMART-L-MM uses an upgraded AESA radar panel over the original PESA, allowing for the use of a new radar emission frequency tailored towards ballistic missile tracking whilst also continuing to operate in AAW frequencies unaffected. (For context, PESA radars are limited to using one narrow frequency band at a time due to the use of one TRM (Transmit-Receive Module) to control all antennae on the array).

Other changes include improved return signal processing to better identify extremely fast moving targets and improved coverage at high beam elevation, allowing for a better track of targets with steep trajectories (a defining characteristic of ballistic missiles). This upgrade has been implemented on the four Royal Netherland Navy’s De Zeven Provincien class frigates, amongst several land-based installations.

These upgrades intend to improve tracking performance against fast moving ballistic targets whilst retaining existing AAW search and track capability. Instrumented range has reportedly also been increased to 2000km (it should be noted that a target at this range would need to be detected at an altitude of ~230km, similar in altitude to the apogee of a 1500km range MRBM like that of the DF-21D).

Real world tests of a ground-based system have demonstrated SMART-L-MM’s ability to easily track ballistic targets at an average range of 1500km and transmit this data to the appropriate weapons platform.

S1850M’s capacity to receive this EWC upgrade has been confirmed by Thales Netherlands and would undoubtedly improve the Type 45’s early detection of incoming ballistic threats, albeit with the downside of further Type 45 dry-docking in addition to their PiP (Power improvement Project) dry-docking periods.

Aster (block 0/1/1 NT)

The Aster missile family is a group of surface to air interceptors designed to combat agile, supersonic, low flying anti-ship missiles which appear over the horizon with little time to react. The Aster missile’s design has been tailored to this requirement by emphasising extreme agility in its final stage and high intercept speeds (up to Mach 4.5).

The Aster family comes in two sizes, Aster 15 and Aster 30. Aster 15 and 30 share an identical final phase hit-to-kill ‘dart’, whereas Aster 15 has a shorter first stage booster to allow the missile to fit in the smaller Sylver A43 vertical launch cell (Aster 30 fits in the longer Sylver A50 and A70 cells).

The Type 45 Destroyer uses a mix of Aster 15 and 30 missiles in its 48 Sylver A50 cells.

Once an Aster missile is launched, it is initially guided inertially using onboard sensors and a pre-installed location of the target. At the same time, the first stage booster is ignited to propel the missile up to a certain speed and altitude. Shortly after launch, a data link is established between the missile and the ship which guides the missile towards its target. The first stage booster is also detached once its fuel has been exhausted. 

In the final stage, closer to the target, the Aster ‘dart’ interceptor engages its active radar seeker to locate and destroy the target. It provides real-time input corrections using aerodynamic surfaces and thrust vectoring perpendicular to the direction of travel (a system known as ‘PIF/PAF’) which gives Aster its renowned agility. While Aster is a ‘hit to kill’ interceptor, it is also equipped with a small fragmentation warhead should a kinetic kill be unachievable.

Aster 30 has undergone multiple iterations to improve its effectiveness against ballistic missiles of different classes. Block 0 is the first iteration and is used by almost all naval applications of Aster (including the Royal Navy). It has relatively little ABM (Anti-Ballistic Missile) capability, however it can theoretically intercept a short range ballistic missile in its final stage, low in the atmosphere.

Block 1 is an iteration funded by France and Italy for use in the land-based SAMP/T BMD system. The improvements of block 1 include software improvements to the guidance of the missile and integration with SAMP/T’s Arabel radar. Block 1 also uses an improved warhead which reportedly explodes into larger fragments to better destroy a ballistic target. These improvements officially give block 1 the ability to intercept SRBMs (Short Range Ballistic Missiles) of the 600km range class.

Block 1 NT (New Technology) is a further iteration for the SAMP/T system, to first be delivered to the French Air Force in 2022. There have also been orders for naval use, including implementation on some of Italy’s PPA frigates. B1 NT uses an improved seeker operating in the higher frequency Ka-band. This gives the missile an improved target acquisition range and a thinner angular resolution. This allows for B1 NT to better handle target selection against ballistic missiles with multiple warheads. This gives Aster B1 NT a confirmed ability to counter MRBMs in the 1500km range class. This puts interception of DF21D anti-ship ballistic missiles within the operating scope of the missile.

However, it should be noted that Aster block 0, 1 and 1 NT are constrained to intercepting ballistic missiles of any class within an altitude of ~20km or lower, due to the nature of the missile using aerodynamic surfaces as the primary means of course correction. Aerodynamic surfaces lose effectiveness with an increase in altitude.

Intercepting ballistic missiles in their final stage is not ideal because it proves the most challenging period of interception; the incoming missile is moving at its fastest speed and any movements can change the missile’s course by large distances and nullify interceptors that are already in the air. Granted, it is an improvement over virtually no capability at all and is a welcome upgrade to the UK’s Aster stockpile.

The latest iteration of Aster is block 2 BMD. Little is publicly known about this block besides an increased focus of BMD against targets greater than the 1500km range MRBM class. It has been speculated to use an exo-atmospheric kill vehicle to target ballistic missiles in earlier stages of flight, albeit to a lesser extent than similar competitor missiles due to the supposed requirement to fit in shorter Sylver A50 Vertical Launch Cells.

With very little input from MBDA on the state of the program, it may have been cancelled in favour of the land-based TWISTER European BMD program. One notes that a land-based system may be more feasible for a mainland European project which is more focused on ICBMs from Russia than creating a BMD umbrella over a naval fleet/carrier strike group operating near the South China Sea.

Standard Missile 3

Endo/Exo-atmospheric interceptors focus on intercepting ballistic missiles in a far more vulnerable stage of flight, the mid course. This occurs high in the atmosphere (from ~80-250km in altitude for an MRBM). At higher altitudes, the effectiveness of aerodynamic control surfaces is greatly reduced and subsequently a ballistic missile’s ability to sharply manoeuvre is hampered. This makes for a far easier target, provided the interceptor is technologically capable of reaching and manoeuvring at such altitudes.

The SM3 (Standard Missile 3) is an American ship-based BMD missile with versions capable of intercepting IRBMs (Intermediate Range Ballistic Missiles) of a range class far greater than that of the anti-ship DF21D. The SM3 is a four stage missile with 3 propulsion stages in order to propel the interceptor to such high altitudes that it can intercept ballistic missiles in their vulnerable mid course stage.

The final stage of an SM3 works differently from that of Aster through the use of a LEAP (Lightweight Exo-Atmospheric Projectile) and a TDACS (Throttleable Divert and Attitude Control System) to intercept a warhead when aerodynamic surfaces are not a viable means of course correction. The LEAP will use onboard sensors to locate the ballistic missile and align its trajectory with the target, relying on the release of kinetic energy at the point of impact to obliterate the target.

This method of interception, albeit unreliable in early iterations, has proven to be far more successful at intercepting a greater range of ballistic targets than focusing on a re-entry phase interception like that of Aster block 1 NT. A missile that operates in this way should be a procurement focus for the Ministry of Defence, should they (rightly) consider BMD a priority upgrade for the Type 45 Destroyers.

A procurement of SM3 would also benefit from continued testing and funding from both the US and Japanese governments (of which SM3 is in service for both nations onboard Aegis ships). However, there may prove to be increased costs due to the necessary installation of 16 additional Mk41 strike length cells to facilitate the larger missile and the costs of integration with the Type 45’s Combat Management System.

Summary

Should the MoD finally decide ship-based BMD is a capability worth investing a useful amount of money into, there are a variety of options available to develop both the search and track and hard-kill interception of ballistic threats. With a continuing doctrinal shift in naval deployments to the Asia-Pacific region, it would be plausible for this requirement to grow past the statement of intent exhibited in the 2015 SDSR.

While the CSG2021-attending Arleigh Burke class destroyer USS The Sullivans will be capable of providing a BMD umbrella over the group with the use of SM3s (a capability refined by the inclusion of the Type 45’s radar abilities), the MoD should not become complacent in regards to BMD and invest in a sovereign capability to improve total BMD capacity and reduce the ever-increasing reliance on US military presence to achieve (albeit often aligning) British goals.