New Technology
21 November 03
US begins hypersonic weapons program
By Celeste Biever
The US military has begun development of an ultra-high speed weapons system that would enable targets virtually anywhere on Earth to be hit within two hours of launch from the continental US.
Ten companies have been given grants by the Pentagon's Defense Advanced Research Projects Agency (DARPA) Pentagon for six-month "system definition" studies. If the Pentagon likes the results, a three-year design and development phase will begin.
The ultimate aim, slated for around 2025, is a reusable Hypersonic Cruise Vehicle (HCV) that can take off from a conventional runway in the US and strike targets up to 16,700 kilometres (10,350 miles) away.
"There is a strategic military need to be able to strike potentially dangerous military targets that are far away and may only be accessible for a short period of time," explains Daniel Goure, an analyst at the Lexington Institute, a think tank in Washington DC.
Current cruise missiles travel relatively slowly, meaning a target may move before it arrives. One solution is to use military bases in foreign countries, but this brings political and logistical difficulties. A hypersonic weapons systems solves both problems.
However, experts describe the technical challenges posed by the program as "tough" and "challenging". Tearing through the atmosphere at hypersonic speeds requires materials that can withstand the phenomenal temperatures produced by air resistance. Travelling above the atmosphere, in space, avoids this, but would require the creation of a new type of rocket-plane hybrid vehicle.
Twin track
The Pentagon has split the project into two tasks. The nearer-term task, aiming for 2010, is the development of a weapons delivery system and rocket to launch it. The Common Aero Vehicle would be an unpowered but manoeuvrable hypersonic craft capable of carrying about 500 kilograms of munitions over a range of 5500 km.
The CAV would be launched into space by the new rocket, before being guided down by GPS to its target. DARPA hopes the rocket could also be used for satellite launches and such a launcher will be unveiled on 4 December by California-based company Spacex, one of the grant recipients.
The CAV would be used in the longer-term HCV project. Several bomb-laden CAVs would be fitted inside the HCV to provide its firepower. But the HCV will be a much bigger technical challenge.
It will need to fly like an aeroplane, so that it can take off and land on a runway. But air-breathing aeroplane engines will not work above the atmosphere. Therefore a hybrid fuel system would be required, enabling a stored oxidiser to be supplied to the engines when the HCV is in space.
Star Wars
Similar hi-tech projects backed by the US military have not worked out well, for example the 1980's Star Wars program. But Goure is optimistic about the latest program, which is called Falcon: "I don't think there is any reason why we won't be able to do this very well."
But Livingston Holder, of Andrews Space in Seattle, a Falcon grant recipient, says it could be "tough". He says: "We can propel smaller objects at high velocity for short periods of time, but we can't yet cruise across the ocean."
There could also be problems with securing intelligence enabling a target 16,000 km away to be accurately identified. "It's going to be a challenge to be accurate at high speed, but it's not insurmountable," Goure told New Scientist.
© Copyright Reed Business Information Ltd.