Air Power Development Centre

The layers of missile defence

By WGCDR Chris Miller

AMERICA’s National Missile Defence (NMD) system has been generating considerable world-wide controversy of late. Australia is also weighing options for a possible contribution. So, what’s this system all about?

First, a brief history of missile defence. America signed an Anti-Ballistic Missile treaty with the Soviet Union in 1972, which placed limits upon selfdefence measures for each country.

However, in 1983 President Ronald Reagan introduced his Strategic Defence Initiative, or “Star Wars” concept, which arguably did not adhere to the 1972 treaty. “Star Wars”, which was reliant primarily upon space-based weapons, was later cancelled.

Recently, President George Bush decided to withdraw from the 1972 Anti-Ballistic Missile treaty and progress with the development of the NMD system.

His intent is to have an initial capability in place before the next presidential election in late 2004.

The aim of the NMD program is to prevent long-range ballistic missiles – in particular those armed with nuclear, biological or chemical (NBC) warheads – from hitting America.

The shield is primarily intended to defend against a small number of missiles launched by terrorists or a rogue state. Notably, it is not expected to be able to defend against a mass launch of Russian or Chinese missiles.

The mature NMD system will have a number of “layers”, enabling it to detect and intercept missiles in either the ascent, cruise or descent phase of flight. A variety of sensors and weapons, on land, at sea and in air and space, will be used to provide this defensive umbrella.

Several large, land-based early warning radars are being upgraded. These will enable missiles to be tracked and engaged during their cruise phase.

In conjunction with these radars, purpose-built self-defence missiles are currently being developed and will be sited in Alaska and California.

The missiles are designed to shoot down ballistic missiles in their cruise and descent phases.

However, given the very high speed of the ballistic missiles and accuracy required, this is technically very difficult and can be likened to hitting a bullet with another bullet. Hence, the effectiveness of such a system is open to considerable debate at this stage.

25-year defence agreement with US

AUSTRALIA and the US intend this month to sign a 25-year Memorandum of Understanding on cooperation in missile defence to formalise Australia’s commitment to the US-led missile defence program. A key initial project would be to undertake jointly exploratory cooperative research and development activities to investigate the potential for the Jindalee over-the-horizon- radar technology to be used in missile defence. Other potential areas for participation in the program included greater cooperation in ballistic early missile warning through ship-based and ground-based sensors.

In the maritime environment, a sea-based radar – some 25 stories high – is currently being built and will be permanently sited off the coast of Alaska. Also, US Navy Aegis-class cruisers will be modified to track and shoot down missiles using a modified version of their current SM-2 theatre air defence missile.

For the air segment, several Boeing 747 aircraft are being modified to each carry a high-powered laser.

The intention is that a B747 will patrol in the vicinity of likely missile launch sites. After a missile launch is detected, the B747’s laser will be used to destroy the missile during its ascent phase.

The prospect of debris falling back onto one’s own country (in particular, NBC warhead debris) provides a significant deterrent against missile launch. The first modified B747 is due to commence flight trials around 2005.

Another layer of the defensive umbrella is from space. An existing satellite system designed to detect and track ballistic missile launches is currently being upgraded.

The most contentious part of the defensive umbrella comprises a proposed system of space-based weapons to shoot down ballistic missiles while they are still in space.

Like the land-based missile system, this is a very challenging technical task. Also, it presupposes putting weapons into space – hitherto a sanctuary from any weapons.

The entire program is extremely expensive – some US$100 billion.

There will no doubt be much further debate before the eventual system comes to pass.

Wing Commander Miller is the Deputy Director Future Space Future Concepts at the Air Power Development Centre.

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