National Geographic : 1999 Jun
The Measure of an Astronaut "It's really not that uncomfortable," says Glenn of the weblike head gear he wore for sleeping-brain-activity studies aboard Discovery (above). "You're weightless, so your head doesn't press down on the sensors." In a study of the effects of space flight on a 77-year-old's bone density, Glenn had full-body x-rays taken before and after the flight (above right). In a shuttle mock-up in Hous ton (right) instructor Sharon Jones gauges the distance between Glenn's seat and the locker-mounted proce dure cards. The seat is secured to the floor, so Glenn's eyes have to be able to span the gap. Watching Glenn watch the wall is his wife, Annie.