michael najjar photographs "short arm centrifuge (sahc)" at the german aerospace center.
michael najjar has photographed the short arm centrifuge (sahc) at the german aerospace center (dlr) in cologne for his new series. the short arm human centrifuge or sahc exploits the physics of rotating objects. it generates centripetal and centrifugal force which are the two physical forces needed to keep a body in orbit. the faster the speed of rotation and the further the subject is from the center of rotation, the higher the centrifugal force impacting on the body will be. test person experience an artificial gravitational force as their feet are pressed against the bottom of the nacelle so that they imagine they are standing even though they are actually lying down. at 45 rotations per minute people experience a gravitational force corresponding to over six times their own body weight. long-term biological and medical experiments have shown that zero gravity conditions cause significant changes to the metabolism of human muscles and bones. astronauts in space lose around one percent of body mass per month in the region of the lower spine, hips and upper thigh bones. scientific work at the dlr is designed to develop effective countermeasures to the neuromuscular and skeletal degeneration awaiting astronauts in space.