HYPERSONIC DEFENCE Chapter 1 EARLY WARNING

When threats are approaching at speeds of Mach 5 and higher, time is of the essence.

The sooner the defenders can detect that danger is coming, the better!

The range at which we want to detect such targets is driven by three factors:

1. Intercept range – a larger intercept range allows protecting a larger area;

2. Velocity of the threat – the faster these are, the earlier we need to launch our interceptor to achieve the required intercept range;

3. Decision making time – the more time that is needed to take such a decision, the longer the initial detection range need to be to achieve the required intercept range.

With above considerations we find range requirements in the same order of magnitude as for ballistic missiles, but because these targets fly lower, there will be more horizon limitations.

Not surprising, therefore, that the capability for failure-proof warning, as early as possible, is a first essential building block for any protective shield against Hypersonic Threats.

Numerous Early-Warning solutions, including Space, Stratospheric and Surface-Based capabilities are currently under development.

Quite literally, the highest level of Hypersonic Threat Defence is to have sensors positioned in space, in the stratosphere and even on the ground that can provide the Early Warning and persistent tracking that is so vital.
This type of capability should always be an integral part of a wider Missile Defence architecture.
It should for example be interoperable with NATO, EU and/or other allied networks or systems.
Key missions of the space or stratospheric sensors would be to: 

•    Observe in real-time space launches and perform space surveillance.
•  Provide intelligence on Ballistic, Hypersonic, and Anti-Satellite Missile test firings, test flights and where possible the associated warhead technology developed by potential adversaries.

Sensors installed on satellites in space and/or on stratospheric air vehicles, can address launches of missiles into space, including ground, sea or air-launched hypersonic missile threats, from any given geographical sector within the sensors’ field of view. These include: 

•    Ballistic missiles…
•    Hypersonic boost-glide vehicle(s)…
•    Hypersonic cruise missile(s)...
•    Covering the various types of missile ranges, trajectories, for single-firings as well as missile salvoes.

Capabilities provided would include missile launch detection in real time, with a low rate of false alarm. Furthermore, these sensors could help to characterize and ultimately identify a detected missile, its launcher (and launch originator), new space objects and their manoeuvres.

The trajectories of detected launches would be measured or calculated from launch to the ballistic phase. Purely based on ballistics, it is no longer possible to reliably predict the impact points of hypersonic missiles, once they start manoeuvering. However, sensors watching from space or stratospheric altitudes combined with ground-based ones can provide persistent tracking during the relevant parts of the threat’s trajectory. Using these inputs, continuously updated predictions can be made of the threat’s impact point, based on its manoeuvers, remaining energy and other factors.

Operating as part of a wider defensive network, detected threats would typically be handed over to different early warning sensors (including surface-based ones, see below) through national or alliance C2 structures. Meanwhile, the space or stratospheric sensors would continue to contribute to the Hypersonic Threat Defence mission, where possible all the way to the end of the missile’s flight.

Thales is contributing to the development of space-based early warning capabilities in a multi-national context. For stratospheric deployment of Early Warning sensors, Thales is proposing its Stratobus stratospheric airship concept. That could for example be equipped with a high-resolution electro-optical sensor package derived from the proven OSF sensor system of the Dassault Rafale fighter aircraft.

For optimum results, any Hypersonic Threat Defence architecture should also include multiple Surface-Based Early Warning sensors. These may be of different types and origins, be they U.S., European or other, as long as they are integrated within the overall C2 network. 

In general, surface-based early warning radars are designed to detect and track at (very) long ranges, current and emerging threats in the Integrated Air & Missile Defence and Space domains.

Advanced radar technologies such as fully digitally-controlled, Gallium Nitride (GaN)-powered, multi-mission Active Electronically Scanned Array (AESA) arrays, Dual-Axis Multibeam receiver technology and innovative waveforms provide incredible accuracy, clutter suppression and extended long range, out to 1,200 km and beyond. These performances have been tested and proven during live Ballistic Missile Defence tests in close cooperation with the U.S. Navy. Longer ranges can be achieved with Over-The-Horizon radar although such technologies are less mature.
The near future will see surface-based early warning radars provide a 360-degree Early Warning capability against Ballistic Missiles and Hypersonic Missiles, while simultaneously performing surveillance and tracking against conventional air targets such as aircraft, missiles or drones. 

This enables for example a ground-based radar that is protecting a critical asset such as a command centre and major cities, or a naval surface warship that is protecting an aircraft carrier, to simultaneously provide Local Area Air & Missile Defense, as well as provide Early Warning against hypersonic-speed and 3D-manoeuvring targets flying at high altitude. The latter could typically be either Hypersonic Boost Glide Vehicles (HGV), Hypersonic Cruise Missiles (HCM) or manoeuvrable re-entry vehicles deployed by Anti-Ship Ballistic Missiles (ASBM). 

From a Thales perspective, surface-based radars are on offer in several sizes and designed to operate in different frequency bands (S-, L- or UHF-band), each with their own unique advantages including those mentioned above.
Already ordered by several NATO countries is the SMART-L Multi Mission (MM) Radar, that can be either land- or sea-based. Under development are the UHF Deployable Early Warning Radar and the Ground Alerter family of UHF radars.