The skeleton in space

Abstract

Calcium loss experience by astronauts under weightless conditions is discussed. I-125 photon absorption measurements on astronauts on the Apollo 14, 15, and 16 flights showed bone density decreases of 6.6 percent in one astronaut and 7.3 percent in another. The estimated total body calcium loss on Apollo 17 was 0.2 percent. The test results indicate that calcium losses occur mainly from the weight-bearing parts of the skeleton. Measures to counteract the losses include 'penguin' suits, maintenance of nutrient intakes at high levels, and extensive exercise on ergometer and treadmill.