Images Dated 11th November 2003

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X-43B aircraft

X-43B aircraft. Computer artwork of NASA's X-43B or Hypersonic Experimental Vehicle (Hyper-X) in flight. The Hyper-X programme was started in 1996 to test the scramjet-powered jet engine and to design a plane that could be used at hypersonic speeds. The scramjet engines, unlike rockets that must carry both oxygen and fuel, use oxygen from the air scooped up as the aircraft flies at over 5 times the speed of sound (Mach 5). The X-43A craft broke up on its test flight in 2001, which has now been attributed to modelling inaccuracies during the design stage. The X-43B is a much larger plane than the X-43A and if constructed is to be used as a reusable launch vehicle for spacecraft

© NASA/SCIENCE PHOTO LIBRARY

Crystals of cholesterol

False-colour scanning electron micrograph of crystals of monohydrate cholesterol percipitated from alcohol & water (plate form). Cholesterol is a sterol, a fatlike material synthesised by all animal cells. It is a major constitutent of the cell membrane, a precursor to the formation of sex hormones & the source of bile salts. A third of body cholesterol is made in the liver. Its excretion, directly or as bile salts, is the sole responsiblitiy of the liver. Body cholesterol is added to by dietary cholesterol from meat & dairy products. High levels are associated with atheroma & coronary heart disease but the relationship is unclear. Magnification: x70 at 6x4.5cm size

© DR JEREMY BURGESS/SCIENCE PHOTO LIBRARY