Magazine article Science News

Shuttle Mission Yields Surprising Results

Magazine article Science News

Shuttle Mission Yields Surprising Results

Article excerpt

Biologists may have to rethink traditional theories about how the human body functions in light of new results from experiments conducted on shuttle astronauts during last June's Spacelab Life Sciences-1 mission, scientists announced last week.

"It is now clear that we are obtaining a significant number of surprising results from this mission," says Ronald J. White, chief scientist in NASA's life science division in Washington, D.C. "The ideas the investigators had prior to the space flight about how the body actually would work in space were either incomplete or incorrect."

Some of the most important findings relate to the detailed workings of the cardiovascular system. "One of the major concerns regarding the body's adaptation to space flight is that the adjustments the cardiovascular system makes during flight to maintain blood pressure in weightlessness may compromise its ability to readjust to gravity upon return,' says David R. Pendergast, a physiologist at the State University of New York at Buffalo.

In a study presented July 24 at an American Heart Association meeting in Chicago, Pendergast and his colleagues found that cardiac output -- the volume of blood pumped by the heart -- increased 50 percent and remained elevated throughout the shuttle flight, even though heart rate decreased and mean blood pressure remained constant. "This type of regulation of blood pressure was completely unexpected," Pendergast says.

On the ground, cardiac output rises temporarily every time a person lies down. The physical effects of weightlessness resemble those of prolonged bed rest, so astronauts may feel weak or have difficulty standing for several days after landing. According to Pendergast, models for weightlessness based on bed rest studies redicted an initial increase in cardiac output, followed by a decrease to normal levels within one to three days. …

Search by... Author
Show... All Results Primary Sources Peer-reviewed

Oops!

An unknown error has occurred. Please click the button below to reload the page. If the problem persists, please try again in a little while.