Astronauts experience a range of physiological and clinical changes while living in space. However, relatively little is known about the potential longterm effects of space flight or overall risk of being an astronaut. In 1992, NASA designed a protocol, called the Longitudinal Study of Astronaut Health (LSAH), to examine these effects. Ten years later, NASA requested help from the IOM in assessing the study and making any necessary midcourse corrections.

The resulting IOM report, Review of NASA's Longitudinal Study of Astronaut Health, makes recommendations for improving the validity of the LSAH as a database for monitoring the health of astronauts and for research on the effects of space on humans. The committee also recommends that NASA should assume responsibility for the lifelong health care of its active and former astronauts.