National Academy of Sciences
Washington, D.C.

As Space Missions Become Longer, Effects on Body and Mind Need Study

Construction of the International Space Station scheduled to start later this year marks another milestone in space exploration. Research missions that once lasted only a few weeks, could routinely last many months, even years. But health effects of the space environment observed during short flights raise concerns about the safety and performance of astronauts during longer missions.

Because these detrimental effects could be intensified by extended missions, NASA should support additional research into the consequences of space flight on the biology and behavior of humans and other organisms, says a new report from a committee of the National Research Council.

The report provides a comprehensive review of the findings to date from a wide range of life sciences research for space. It also outlines the areas of research on humans and other organisms that NASA should pursue if it is to successfully achieve such long-term goals as operating the International Space Station, colonizing the moon, and sending humans to Mars.

NASA should mount at least one more Spacelab-type mission to continue the momentum of life sciences research in space and generate additional data on the biological and psychological effects of space travel, the committee said. It recommended specific research priorities to ensure the safety and optimal performance of crews on future extended missions.

NASA should concentrate on fully understanding how weightlessness affects bone and muscle mass, blood pressure, sensory orientation, and movement, in order to devise effective countermeasures, the committee said. Losses in bone and muscle mass pose two of the greatest obstacles to health and safety on long missions. Crew members on the Russian space station Mir showed an average loss in bone mass density of up to 1 percent a month in weight-bearing bones, the report notes. Significant muscle atrophy has been recorded after only five days in space. In-flight exercise programs proved helpful, but did not fully prevent deterioration.

Changes in cardiovascular and pulmonary function have not yet been a hindrance during space flight. However, two-thirds of the astronauts tested after flights showed an impaired ability to maintain adequate blood pressure. This condition could have more serious consequences during docking and landing maneuvers involving rapid transitions between gravitational force levels.

The agency should use the latest advances in molecular and cellular biology to explore the underlying processes by which humans respond to changes in gravity, the report says. Low gravity alters the body's ability to sense direction and control motion, sometimes impairing astronauts' ability to walk when they first return to Earth. This condition could be exacerbated, the committee observed, and could undermine the crew's abilities to operate the craft or disembark rapidly in an emergency.

While space-based research will be crucial for advancing knowledge in these areas, most research funding should be directed to ground-based experiments -- which are less costly to conduct -- to answer fundamental questions and frame hypotheses for testing in outer space. For example, self-supporting colonies in outer space will require the cultivation of plants in completely contained environments for food and an oxygen source. So far this has not been successfully achieved either on Earth or in space, the report notes.

The report emphasizes the need for more research on the impact of the space environment's isolating and confining nature on astronauts' behavior and performance. This is one of the least-studied effects of space flight, yet the compatibility of crew members and their mental well-being can greatly influence the ultimate success of a mission.

NASA also should improve its collection of data from astronauts to answer fundamental questions about the effects of space travel on the human body and mind. This process thus far has been arbitrary and often hindered by astronauts' concerns about confidentiality. The agency should revise its policies and practices to create a more systematic approach to collecting and disseminating such information, and encourage full cooperation and compliance from the astronauts.

In addition, NASA should encourage more timely publication of results of experiments in peer-reviewed journals, and the agency should provide the funding necessary to analyze and archive data so that it is readily accessible to the scientific community.

The study was funded by NASA. The National Research Council is the principal operating agency of the National Academy of Sciences and the National Academy of Engineering. It is a private, non-profit institution that provides science advice under a congressional charter. A committee roster follows.

Copies of A Strategy for Research in Space Biology and Medicine In the New Century are available from the National Academy Press for $49.00 (prepaid) plus shipping charges of $4.00 for the first copy and $.50 for each additional copy; tel. (202) 334-3313 or 1-800-624-6242.

Full report is available for online viewing at:

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