On Earth, gravity plays a key role in the function of human physiological systems. Bones and muscles provide support and structure to the body and the ability to move around in Earth's gravity. The neurovestibular system uses gravity for the detection of body orientation, motion, acceleration and balance. The cardiovascular and muscular systems work together to circulate blood and other fluids through the body; thisincludes pumping blood upward from the feet and legs, against the downward pull of gravity.
Space flight places humans in an environment unlike any found on Earth. Microgravity, or the nearly complete absence of gravity, is perhaps the most prominent obstacle that astronauts face. It requires a significant modification of living and working habits by the astronauts. Not only do they have to learn to adapt to the way they perform routine operations, such as eating, moving and operating equipment, but they must also learn to adjust to the internal changes that their bodies experience in microgravity.
During the early space flights in both the U.S. and Soviet programs, scientists observed a variety of changes in astronauts and cosmonauts, including decreased exercise capacity, altered body fluid volumes and electrolyte levels, disturbances in the neurovestibular system, muscle atrophy, a loss of red blood cell mass, decreased bone density, and reduced cardiovascular performance. Observations made during these early flights caused scientists to continue their research on longer duration missions, such as the United States Skylab missions and the Soviet Union's Salyut missions.
All of this past research has led to today's current Human Life Sciences research, in which United States and Russian scientists worked together in the Shuttle-Mir program to determine how the human body adapts to the microgravity environment. Scientists will use the knowledge gained from Shuttle-Mir to assure crew health and safety on future space stations. These results may also contribute to current scientific and medical knowledge, thus improving the quality of life on Earth.
Cardiovascular Studies - Study the methods to reduce the cardiovascular readaptation effects of long periods in space.
Endocrinology - Studies designed to examine hormonal responses in microgravity.
Hematology - Studies designed to examine loss of red blood cell mass in microgravity.
Human Factors - Study of physical and mental coordination during space flight.
Immunology - Studies designed to examine physiologic responses to fluid redistribution in microgravity.
Microbiology - Study the environmental and microbiological characteristics in the spacecraft.
Muscle and Bone - Study the effect of microgravity on the muscles and bones of astronauts.
Neuroscience - Study of the changes occurring in the Central Nervous System (CNS) of the human body during a stay in microgravity.
Pharmacology - Space pharmacologists study how weightlessness may affect the appearance, chemistry, actions or uses of drugs.
Radiation Studies - Study the radiation characteristics in the spacecraft as well as the effect of radiation on crewmembers.
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Page last updated: 07/16/1999