Images Dated 6th September 2002

Car driver using hand-held GPS receiver

MODEL RELEASED: Satellite navigation. A car driver checking his location with a hand-held satellite navigation receiver. The system uses signals sent by the network of 21 Navstar Global Positioning System (GPS) satellites. Each satellite sends out a signal with its identity, position and the exact time from an atomic clock. The receiver reads these data and can instantly calculate its position anywhere in the world to within 100 metres. This is one of the new generation of GPS receivers which are portable and affordable to the general public. GPS has benefits to a wide variety of users, including hikers and climbers, sailing enthusiasts, private pilots and vehicle drivers

© DAVID PARKER/SCIENCE PHOTO LIBRARY

DNA artwork

DNA. Computer illustration of part of a molecule of beta DNA (deoxyribonucleic acid), the genetic material found in all living cells. Beta DNA spirals clockwise when viewed from above. The DNA is seen unravelled at lower left. DNA encodes and controls all the hereditary traits of living organisms. It consists of two strands wound around each other in a double helix. The strands each have a sugar-phosphate backbone (purple) connected by paired nucleotide bases (yellow, green, brown & blue). It is the sequence of these four types of bases which determines the unique genetic code of an individual

© HENNING DALHOFF / SCIENCE PHOTO LIBRARY