1. a Blackett Laboratory, Imperial College, University of London , London, England
2. b Space Department , Royal Aircraft Establishment , Farnborough, Hants, England
3. c Marconi Research Laboratories , Great Baddow, Chelmsford, Essex, England
4. d Aerospace Group, Logica Limited , 64 Newman Street, London, W1A 4SE, England
5. e Department of Geography , University of Reading , Reading, Berks, England