Space Shuttle Astronauts Pedal Around World
The space shuttle Columbia’s astronauts got an orbital workout Friday as they pedaled at full speed around the world to see how their bodies were holding up after nearly two weeks in space.
One by one, the crew members worked their way from 30% of maximum exercise capacity on the shuttle’s stationary cycle to 60% and then to 100%. They breathed into a tube connected to a gas analyzer as they cycled; their heart rates and blood pressures also were monitored.
“This may not feel so good to do, but it’s very important in understanding the absolute capacity of our cardiovascular system to deliver oxygen to the tissues of the body, particularly the muscles,” astronaut-physician David Wolf said before hopping on the cycle.
Muscles weaken in weightlessness, as do bones. Wolf and the three other scientist-astronauts aboard ingested and injected one another with calcium Friday to see how it is absorbed by the body in space.
Researchers involved in Columbia’s 14-day medical mission want to know whether bone loss in weightlessness is caused by increased bone destruction, decreased bone formation, or both.
The dissections today of some of the 48 rats aboard the shuttle--a space first--should help answer that question.
The remaining animals will be killed for dissection after the flight.
The flight, the longest ever for a shuttle, is due to end Monday with a landing at Edwards Air Force Base in California.
Medical Research in Space
Astronauts aboard the space shuttle Columbia have been performing experiments in medical disciplines ranging from neuroscience to cardiovascular physiology during their two-week mission. Some of the notable projects include:
Weightlessness: A study of the effects of weightlessness on the cardiovascular system. The experiment requires astronauts to spend time in a vacuum sack that forces blood and other body fluids from their chests into their legs. Researchers want to see if the treatment keeps them from becoming dizzy once they are back on Earth, a common complaint of returning astronauts.
Muscle mass: A determination of how protein metabolism is changed in space--an effort to determine why muscle mass decreases during long space flights. Each crew member is weighed daily and a log is kept of all fluids and total nitrogen intake, among other things.
Body fluids: An examination of how space flight affects body fluids and disturbs body electrolytes. Zero gravity causes a fluid shift toward the head, which causes a perceived increase in the body’s blood volume. Measurements of blood, urine and saliva are being taken.
Calcium loss: Tests to determine how space flight causes a loss in the body’s calcium level. Researchers believe that significant changes in hormones may be associated with calcium loss.
Sensory organs: A probe into how the body handles the loss of information, such as the loss of the sense of gravity, when it has redundant paths of such information. Space sickness, which affects many astronauts, is believed to be related to the brain’s confusion when it receives conflicting information from the inner ear and from other sensory organs.
Animal testing: The Columbia carried 48 rats into space as part of a study of life processes in zero gravity. Astronauts will use a laboratory guillotine like this to behead and dissect six of the rats in space so that their systems will not readjust to gravity. The other 42 rats will be kept alive for examination on Earth. Among other things, NASA wants to see how zero gravity affects calcium levels and hormones in the rats’ internal systems.
