WHEN NASA鈥檚 record-breaking hypersonic X-43A aircraft dived into the ocean last week, the space agency鈥檚 budget for hypersonic civil aviation research sank with it. The technology will instead wind up at the Pentagon, where it will be used to build a bomber that can attack targets anywhere in the world within 2 hours.
Last week鈥檚 Mach 9.8 flight capped a 40-year quest to demonstrate hypersonic flight. 鈥淲e showed that it鈥檚 real,鈥� says Chuck McClinton, technology manager for the Hyper-X programme at NASA鈥檚 Langley Research Center in Virginia.
While the flight garnered newspaper headlines of a future in which hypersonic aircraft fly civilians from London to Sydney in 2 hours, the stark reality is that NASA cannot afford to undertake the research to make it possible. Its focus is now firmly on exploring the moon and Mars. NASA engineers will merely support hypersonic development at the Air Force Research Lab and the US Department of Defense鈥檚 research agency, DARPA.
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The handover was dictated from the top. NASA chief Sean O鈥橩eefe praised the X-43A speed record as a 鈥渒ey milestone鈥�, but last January he cancelled the planned follow-on X-43C programme because research into air-breathing hypersonic scramjet technology cannot contribute to the development of launchers for the moon-Mars programme.
A scramjet-powered aircraft is carried up to supersonic speed by a rocket or jet. Fuel injected and combusted with air at this speed enables the craft to travel even faster. This allows a scramjet to reach speeds that only rockets can otherwise attain. But while rockets have to carry their own oxygen, scramjets scavenge theirs from the atmosphere, making them far more efficient.
The Hyper-X programme started more than a decade ago, supported by both NASA and DARPA. The two agencies envisioned a two-stage spaceplane with a standard jet engine to get it off the ground and a scramjet to take it to Mach 10. NASA鈥檚 goals were improved access to space and hypersonic civilian aircraft, while the Pentagon was thinking along the lines of a massive bomber that could fly to the edge of the atmosphere.
鈥淭he stark reality is that NASA cannot afford to undertake the research to make hypersonic civilian flight possible鈥�
DARPA has also recently incorporated technology from NASA鈥檚 abortive X-37 spaceplane into a space bomber programme called Falcon, short for Force Application and Launch from the Continental US (New Scientist, 25 September 2004, p 7). The first step is to develop a launcher that could use air-breathing hypersonics for part of its journey. DARPA wants the near-space bomber ready by 2010. The idea is to eradicate the need to use regional air bases.
Meanwhile, the US Air Force, working with Pratt & Whitney, is building a Scramjet Engine Demonstrator to study prospects for Mach 7 missiles about the size of the 3.6-metre-long X-43A that could be launched from fighter jets to strike other fast aircraft or missiles.
