Should we be scared?  We've all read the warnings about 'killer
nanobots' and 'grey goo'. But how seriously should we take the
hype about nanotechnology? Ian Sample tours some labs to find
out  On the outer edges of Farnborough stands a large, ugly,
aluminium-clad building. Once the home of a wind tunnel for
testing the aerodynamics of British missiles, it now houses a
hi-tech production plant. In the space of an hour, the plant
takes a few kilogrammes of metal or metal oxide and blasts them
with an inert gas heated to 9,000 degrees. The vaporised
material then cools to form billions and billions of tiny
particles. These "nanoparticles" are just a few billionths of a
metre across, and can be incredibly useful in a wide range of
applications.  The Farnborough site, which opened this summer,
is, naturally, a source of great pride to Qinetiq, the research
company that owns it. After all, this is cutting-edge. The plant
is one of Europe's most advanced nanotechnology facilities, and
nanotechnology, of course, is