Background

The absence of gravity in space poses unique considerations on all fronts, including the effects on the human body. Because movement in a weightless environment requires minimal physical effort on the part of the astronaut, and because the heart does not need to work as hard to pump blood upward in microgravity conditions as it does here on Earth, lengthy space missions can diminish the body’s overall fitness level. As a result of decreased physical exertion and other related factors, astronauts have experienced physiological changes including muscle atrophy, bone density loss, decreased receptiveness to medications, circulatory issues, and a weakened immune system. Future space exploration will challenge NASA to answer many critical questions about how humans can live and work for extended missions away from Earth.

Solution

By eliciting physiologic responses on Earth that are similar to those experienced by the human body in space, scientists can test and refine theories and procedures to extend our understanding and develop countermeasures to protect humans from the effects of space travel. USRA scientists lead the NASA Flight Analogs Project (FAP) from Johnson Space Center providing NASA with a ground-based research platform to complement spaceflight investigations. One such study measures the effects of prolonged bed rest while subjects lie with their heads lowered by 6°. As Earth’s gravity pulls fluids downward toward the head and reduces physical loading on the bones, muscles, and cardiovascular system, the test subjects experience similar low-gravity conditions as astronauts floating in space.

Results

As part of the bed rest study, scientists have been able to test countermeasures that may reverse the effects of microgravity conditions. Artificial gravity, high frequency vibration, and pharmaceuticals are among the countermeasures being investigated.

Because access to the resources required to conduct studies in space is very limited and the expense of flight studies is significantly greater, use of ground analogs, such as the bed rest study is essential. Flight analog testing will become increasingly critical to NASA to validate countermeasures, given the few opportunities to use flight platforms such as the Shuttle and limited crew time aboard the International Space Station (ISS). Using Flight Analogs is one way NASA will answer the challenges and issues related to space exploration, ensuring astronaut safety and productivity on extended missions.