If NASA plans to one day pull off a manned trip to Mars, the agency will have to overcome a number of potential health hurdles for its astronauts that could have long-term effects on them.
The New York Times reported that while NASA has overcome some problems, such as the use of drugs and exercises to overcome the effects of weightlessness on the bones, others prove more challenging.
Astronauts, for example, have trouble eating and sleeping enough while in space, according to the Times. Another big unknown is the effect higher doses of radiation in space will have on the body after a trip to and from Mars, which would last an estimated two years.
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Because the human body is roughly 60 percent water, body fluids tend to float upward into the chest and head in space, increasing the pressure on the skull.
"Your head actually feels bloated," Mark E. Kelly, a retired NASA astronaut and husband of former Arizona Congresswoman Gabrielle Giffords, told the Times. "It kind of feels like you would feel if you hung upside down for a couple of minutes."
Kelly's twin brother and NASA astronaut Scott Kelly will spend a year on the International Space Station beginning in the spring, 2015 and have his health compared to that of his brother.
"I imagine I'll be giving blood and urine samples," Mark Kelly told the Times. "My attitude is, I worked at NASA for 16 years and whatever I can do to help, I will."
Space.com reported last September that NASA research show that even with the agency's advances in astronauts dealing with bone mass, problems can still occur. For example, calcium in the bones secrete out through urine, making them weak while muscle also lose mass.
Astronauts normally exercise two hours a day in space to fight off the effects of losing bone and muscle but it still takes months for an astronaut to recover from a typical trip to the International Space Station, noted Space.com.
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