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This December 2006 image provided by NASA shows European Space Agency astronaut Christer Fuglesang working outside the International Space Station. A new study published in the journal Science found that astronauts traveling to Mars and back would be exposed to a high dose of radiation. NASA wants to send a crew to orbit the red planet by the mid-2030s. (AP Photo/NASA)

Associated Press
This December 2006 image provided by NASA shows European Space Agency astronaut Christer Fuglesang working outside the International Space Station. A new study published in the journal Science found that astronauts traveling to Mars and back would be exposed to a high dose of radiation. NASA wants to send a crew to orbit the red planet by the mid-2030s. (AP Photo/NASA)
This December 2006 image provided by NASA shows European Space Agency astronaut Christer Fuglesang working outside the International Space Station. A new study published in the journal Science found that astronauts traveling to Mars and back would be exposed to a high dose of radiation. NASA wants to send a crew to orbit the red planet by the mid-2030s. (AP Photo/NASA)
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