Images Dated 29th January 2003

John Stapp during a high G-force test on a sled

Acceleration and deceleration testing. Time-lapse images of John Stapp strapped in a sled seat during high G-force acceleration and deceleration testing. The images run from left to right, starting at upper left. The 27 rocket-propelled runs made by Lieutenant Colonel John Paul Stapp (born 1910) showed the effects of rapid accelerat- ion and deceleration on the human body. On December 10 1954, Stapp reached 632 miles per hour in 5 seconds before being brought back to rest in just over a second with a force of over 40 Gs. Despite initial blindness and collapsed lungs, he quickly recovered, proving that it was possible to survive an ejection from a supersonic aircraft

© NASA/SCIENCE PHOTO LIBRARY

Human sperm cells, SEM

Sperm cells. Coloured scanning electron micrograph (SEM) of human sperm cells or spermatozoa. These tiny male sex cells are produced in the testes, and are responsible for fertilisation of the female egg (ovum). They have a rounded head that contains the male hereditary material (DNA), and a long tail that are used for propulsion. The sperm cell at lower right has some residual cytoplasm seen behind its head, which may affect its motility or fertility. All men have some deformed sperm, but this is not a problem unless their numbers rise. Magnification: x2150 at 6x7cm size

© STEVE GSCHMEISSNER/SCIENCE PHOTO LIBRARY