N space, astronauts don't have gravity to keep them in place. That makes doing even simple tasks difficult. Gene Cernan was the first astronaut who worked on a task outside a spaceship. He said of the experience, "Every time I'd push or turn a valve, it would turn my entire body at zero gravity. I had nothing to hold on to." As he worked, Gene Cernan's heart rate and temperature went so high that his fellow astronauts worried that he wouldn't survive.