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Researchers study 'weightlessness' effects in space

ISS research facility to explore human physiological changes

Astronauts experience several physiological effects while in space  

April 24, 2001
Web posted at: 6:57 PM EDT (2257 GMT)


(CNN) -- Gravity is like milk. It does a body good. The same force that keeps you grounded on Earth makes muscles strong and bones sturdy.

So what happens to astronauts who spend a lot of time -- sometimes weeks or months -- in nearly weightless environments? For 30 years, NASA has been trying to find out.

Because any matter creates a gravitational field, weightlessness is virtually impossible to obtain. However as astronauts move away from Earth in space, gravity becomes weaker and astronauts can feel almost "weightless."


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Last week, space shuttle Endeavour ferried experiments and equipment to the International Space Station's human research facility (HRF) -- a structure that researchers will use to answer questions about the effects of a weightless environment.

The first portion of the orbiting human research facility went into space in February. The second and last part will connect with the ISS next year. But years before a HRF went into orbit, scientists began researching the physiological changes created by a gravity-free environment.

Heads down

At NASA’s Ames Research Center in California, doctors began studying the effects of weightlessness in 1971. During the last 30 years, there have been 40 bed-rest studies at the facility involving about 400 volunteers.

Those studies involve groups of eight to 12 people who continuously lie in beds positioned at a minus 6 degree angle between 24 hours to three months. The angle mimics the effect of fluids flowing to the head and leaving an astronaut’s extremities as they would in space, said Sara Arnaud, a NASA doctor at the Ames facility.

"I play an Apollo CD and we ‘launch’ them," Arnaud said. "Once we ask them to go to bed they are in space. They do not get up."

The subjects eat and read in that position and use bedpans or urinals. Horizontal showers are available.

Researchers have found that in such a state muscles atrophy and bones lose calcium.

Astronauts experience 'puny legs' in space, experts say  

"Astronauts joke about having puny legs," Arnaud said.

Astronaut and physician Ellen Baker told CNN Science Correspondent Ann Kellan she experienced several body changes aboard Russian space station Mir and on three space shuttle missions.

"Your thighs and calves will get thinner because fluid redistributes itself, your face will get puffy," Baker said.

There are other ongoing studies about changes in major organs when the body is buoyant.

The research is valuable, Arnaud said, because it provides information that scientists can use to develop methods to counter the effects that weightlessness produces on the body.

Arnaud said her work serves as a "dress rehearsal" for scientists conducting experiments in space. In 1996, her work for the Life and Microgravity Sciences Mission allowed scientists conducting experiments for that flight to unearth potential problems they might have in space and tweak their experiments involving muscle contractions before the launch, she said.

Into the future

Subsequently, NASA created a Countermeasures, Evaluation and Validation Project, Arnaud said, that recommends all muscular and skeletal experiments have a bed rest study accompany them first.

Many people think resistance exercises might prevent the puny leg syndrome, Arnaud said, but that doesn’t appear to be true. Consequently NASA does not tell its astronauts what exercises to do while in space, Arnaud said.

But the work on Earth does lay groundwork for experiments in orbit on the ISS. Planned ISS experiments include the study of bone and calcium loss, effects on the spinal cord and radiation exposure.


International Space Station:

a free-floating spacecraft that orbits the Earth about 240 miles from its surface and is being built by 16 countries



limbs of the body, especially hands and feet



decrease in size




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