ISS-Based Astronauts Show Microgravity a HealthThreat on Manned Space Missions

S117e08011_small_hsf It appears that astronauts and future space travelers are at increased risks of suffering bone health due to microgravity, which raises serious problems for manned space exploration plans, researchers say, considering that a potential mission to Mars, for example, would take one and a half years to conduct.

At this point, the technology to visit the Red Planet is set in place, but we still need to understand how such a long duration trip to our neighboring planet would influence astronauts' bodies and minds. To test microgravity, an experiment called Mars500 is currently underway in Russia, where six people are locked inside an Erath-based spacecraft simulating a trip to planet for 520 days.

In the study, it was revealed that as far as bone health goes. Astronauts returning from stays on the International Space Station (ISS) need more than a year after returning from the orbital lab to regain their full bone functions.

The scientists who conducted the new work say that space agencies need to develop methods of ensuring that bone density is not lost in space, rather than relying on the fact that astronauts will be able to regain their health by exercising when they return home.

“If we can intervene in space and have crew members not lose as much, that would be the best outcome for them,” explains study researcher Shreyasee Amin, an associate professor at the Mayo Clinic, in Minnesota, Space reports.

Amin and her colleagues studied 28 American astronauts — 24 men and four women. Their preflight ages ranged from 36 to 53, and their missions in space lasted from 95 to 215 days.

The researchers measured the spaceflyers' bone mineral density — an estimator of bone strength — before launch, immediately after landing and again at various times between six and 18 months following their return to Earth.

For a control, the scientists took similar measurements from a sample of 699 people who had never been to space. By comparing the two datasets, the team was able to determine what the astronauts' bone density likely would have been, had they never flown in space.

The team found that some bones remained weak even a year after the astronauts landed, despite intensive exercise and rehabilitation regimes. Hip bone mineral density in particular suffered, Amin said, while other areas, such as the wrist, bounced back faster.

Bones in the hips and legs need to be strong on Earth, because they lug so much weight around on a daily basis. But microgravity frees them of this burden and they seem to weaken as a result, researchers said.

"The hypothesis has always been that it's the lack of load-bearing activity in the lower extremities," Amin told "And that seems to be panning out."

An interesting finding in the research was that women appeared to be losing a lot less bone density than male astronauts. The reason why this happened could not be determined, but the team plans to conduct new studies to find that out.

“There are [still] a few things we need to dice out before we make any definitive decision that we should only send women to space,” Amin jokes.

The researchers did not take into account the health of astronauts that are currently exercising their bodies on new fitness equipment delivered to the ISS. It could be that NASA struck the jackpot with them, but at this point scientists don't have enough data to say whether that's the case or not.

Casey Kazan via


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