Soaring greener heights

Surrey University in the UK, specialising in satellite engineering, is developing a hybrid rocket motor that uses liquid and solid fuel, both of which are environment-friendly This breakthrough could make space satellites much easier and far cheaper to operate

Published: Thursday 29 February 1996

-- As SPACE research becomes costlier, inexpensive propulsion systems are being widely sought. Research with a view to achieving a major reduction in the cost of satellite operation is now underway at the University of Surrey.

At present, it is necessary to employ costly propulsion systems using either solid or liquid fuel to manoeuvre satellites in orbit. The expense is so great that as much as 15 per cent of the cost of a us $6.5 million mini-satellite mission could be attributable to the acquisition of a propulsion system.

The Surrey University system offers a cheap hybrid rocket motor that is believed to be an effective alternative for the sort of small, low-cost mission that is now in increasing demand. Combining the advantage of long-term storage offered by the solid-fuel rocket with the start/stop capability and throttling facility of liquid-fuel one, the Surrey University hybrid would be ideal for transferring satellites from one orbit to another (normally a very expensive operation in terms of fuel and thrust), or for making the regular small orbital corrections that even communication satellites in geosynchronous orbits periodically require.

The Cold War years demanded high-performance rockets of immense power to drive inter-continental ballistic missiles and space-launch vehicles. This in turn, resulted in a preference for such highly toxic but chemically potent fuels as hydrazine and nitrogen tetroxide. By the mid-60s, work on hydrogen peroxide as a propellant had virtually ceased as it was not regarded as a viable fuel for big rockets. However, the political climate today has undergone a change and people are becoming more interested in environmental safety. Hydrogen peroxide is far less toxic than the old and established 'Cold War' rocket fuels and therefore, the Surrey University team chose hydrogen peroxide as the oxidant.

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