Dr. Nelson is the Senior Research Engineer, Fluid Physics and Transport Processes Branch for NASA Glenn Research. She has a BS in mechanical engineering, a MS in mechanical engineering and a Ph.D. in mechanical engineering.
Evolution has designed the human body to thrive under the stresses imposed by the force of gravity. Remarkably, humans can adapt to the radically different environment produced by microgravity. Consequently, astronauts can successfully live and work in space for 6-month rotations on the International Space Station. However, there are some physiological changes that may pose significant risks for astronauts on longer missions, such as a 3-year journey to Mars. Some of the medical conditions under active investigation by NASA are bone loss, muscle atrophy, kidney stone formation, visual impairment and ophthalmic changes, and radiation damage. Perhaps the most profound physiological change is apparent almost immediately upon entering microgravity: a significant portion of the bodily fluids in the lower extremities migrate toward the head. Experiments on Skylab in the 1970s found that each leg reduced in volume by about 1 liter, while the fluid content of the head and upper body expanded. This dramatic redistribution of fluid induces a cascade of physiological responses, and it plays a leading role in some of the medical concerns outlined above. In this talk, we will explore the nature of this fluid shift, medical conditions that are of concern, and countermeasures that may be employed to reduce the risk to spacefaring astronauts.