NASA scramjets starved of oxygen

As the US space agency prepares for its fastest-ever hypersonic flight, political pressure means its research is to be shelved in favour of Moon and Mars missions. Julia Pierce reports.

Unlike boxers and footballers, national space agencies are not supposed to quit when they are at the top of their game. Yet just as NASA is set to achieve the fastest-ever flight by an air-breathing engine next month, it will do just this, effectively mothballing its hypersonic vehicle programme by removing its funding just as it begins to pull ahead of similar technologies under development in the UK, Australia and Japan.

Hypersonic engines, also known as scramjets, use oxygen from the air as a propellant. Once commercially available, their ability to fly without carrying most of their fuel onboard will increase payload capacity for space launches or missiles. According to ambitious claims, they may also lead to the development of passenger aircraft that can skip along the atmosphere, cutting the duration of London-to-Sydney flights to just two hours.

Tests so far suggest that hypersonic technology is not just a blue-sky vision. NASA’s withdrawal could therefore prove highly advantageous to its competitors, leaving them to lead the market as the agency turns its attention to what might become an enormous vanity project.

NASA’s Hyper-X hypersonic research programme is operated jointly by the Langley Research Centre in Virginia and the Dryden Flight Research Centre in California, and aims to demonstrate the capabilities of air-breathing engines for future hypersonic aircraft and reuseable space launch vehicles.

The team’s hypersonics research aircraft, X-43A, last flew in March, when it achieved a speed of Mach 7. The NASA team is now in the process of getting the third X-43A ready to fly. Preparations should be complete by the end of this month, and the flight should take place on 9 November, the first available date at the US Navy’s test range off the coast of Southern California. If all goes well the vehicle will set a new speed record for an air-breathing engine of Mach 10.

But even if the flight is a complete success, the Hyper-X programme appears doomed. With budgets set on a yearly basis, NASA’s focus has always been vulnerable to political pressure, leaving projects that may not provide a tangible payoff in the near term on shaky ground.

Following President Bush’s plans to revive manned missions to the Moon by 2015 and attempt an expedition to Mars, funding for other research programmes has been diverted.

He hopes that the prestige Moon and Mars projects will give Americans hope amid a period of anxiety about terrorism, as well as helping NASA move on from the Columbia disaster.

Bush plans to ask Congress for an extra $1bn (£0.5bn) over the next five years to pay for the Moon mission. But $11bn (£6bn) will also be diverted from other NASA projects, including Hyper-X’s X-43A research aircraft.

Plans to develop a larger hypersonic craft, the X-43C, have been dropped. A resulting single or two-stage launch vehicle would have been completed by 2020-2025. However, the Moon programme has dictated that a new spacecraft must be ready by 2010-2012. Money has, therefore, been channelled into the development of a conventional rocket-powered vehicle.

‘They have decided that we are too far-term for what they want to be done,’ said David Reubush, deputy programme manager for the Hyper-X programme office.

There is a possibility the team may yet receive some additional funding, but this is far from certain, he said. ‘Some folks in Congress disagree with the way NASA’s management has decided to change the budget.

There is currently a $25m (£14m) follow-on in the Congressional NASA Appropriation Bill. However, there is no certainly that this will stay in the Bill. It may disappear. Management is so focused on the task it has to do within a certain time frame that it doesn’t have the luxury of worrying about what the rest of the world is doing. There are schedule and budget pressures to achieve what the President has said he wants to be done. In truth, the future of hypersonics in the US looks pretty bleak.’

Should the US choose Democrat John Kerry over Bush in November’s election, the situation is still unlikely to change. With issues such as international terrorism on the table, NASA is a relatively low priority, no matter who is elected.

The team now hopes to preserve its achievements by linking with other scramjet researchers in the US Air Force. ‘Closing the project will cut off an avenue of potential for the US for as long as it goes into hiatus,’ said Reubush.

But while NASA’s programme has fallen victim to short-termist politics, Australia’s Hyshot programme is making significant progress. Researchers at Queensland University, led by Dr Allan Paull, are currently testing aerodynamic control of a rocket using their engine. Previous tests at the Australian Department of Defence’s Woomera range, 500km north of Adelaide, reached speeds of Mach 7.6.

The team is to launch a baby rocket carrying the reuseable payload Hyshot Zuni I around Easter next year, after technical problems prevented a test this month. The data gathered will be used for trials of three separate scramjet configurations designed by Qinetiq, DARPA and the Japanese Aerospace Exploration Agency (JAXA) in the autumn. Aiming to keep costs down, both the Qinetiq and HyShot teams have approached the project hoping to produce a combustor first, rather than a complete missile or aircraft.

‘We will be doing two Mach 8 flights and a Mach 10 flight next September,’ said Paull. ‘We are continuing with the ground test programme and hope to extend it so that we can contemplate accelerating engines between Mach 8 and 12.’ He appears bemused by NASA’s decision, particularly as his team’s experiments show that development of the technology is perfectly feasible. ‘It would be silly to cut funding when they have finally got a success,’ said Dr Paull. ‘But this doesn’t mean they won’t do it.’

While the Australian team is busy setting future goals it looks as if NASA’s remarkable achievements are to be left to fade away with a whimper. ‘We have enough funding to let us do data analysis through the fiscal year 2005,’ said Reubush. ‘Any follow-on activities have been cancelled.’

If the engines can fulfil their potential, even if the missions to the Moon and Mars are a success, will history judge that for the US sacrificing hypersonic research has been worth it?

On the web