Mighty hearts in space
Space travel was one of our childhood dreams. In the unlikely event that a spaceship had landed nearby, we would have joined the crew without a second thought. Now, we are more cautious recognizing that spaceflight imposes enormous psychological and physiological stresses on our human frames. Rigorous training and extensive medicals including human centrifuge or rotating chair tests are mandatory and we would be likely to fail the tests. On launch day, astronauts are squeezed into tight seats perched on top of a vast volume of highly explosive fuel, and Earthlings can hardly imagine the subsequent severe acceleration. A trip to the International Space Station (ISS) takes about 6 h and then the astronauts fall around the earth, completing one orbit every 90 min for days, weeks, or even months. This free fall and the associated lack of g forces profoundly affects many aspects of human physiology (White & Averner, 2001).