TECH KNOW: Pushing the envelope - Cryonics

Over the ages, immortality has had a bad press. From Jonathan Swift's Struldbruggs - condemned to grow old and spend eternity as dribbling wrecks - to Christopher Lambert's sword-wielding Franco-Scottish time lord in Highlander, negative role models of longevity dominate.

But gloomy examples from the past do not seem to deter supporters of cryonics, a growing band of 'life extension' pioneers whose eyes are fixed on the future. The cryonics faithful believe that, after their bodies have been frozen at or very shortly after death and kept on ice, one day in the distant future they will be defrosted, cured of whatever ailed them and brought back to life, thanks to the inexorable march of medical technology.

THE CHALLENGE: The bodies of dignitaries who died in far-flung regions have traditionally been preserved for the journey home - Lord Nelson was pickled in a barrel of brandy following his death at Trafalgar in 1805.