During the space year of Scott Kelly, the astronaut was mercilessly shut down by radiation – the equivalent of 10 chest x-rays a day for more than 11 months, beginning in March 2015. The attack damaged Kelly's DNA and affected his immune system while increasing his risk of cancer. And Kelly was aboard the International Space Station, whose dense orbit around Earth is in the magnetic field that surrounds our planet and blocks the most harmful forms of radiation.
Astronauts traveling to Mars or other deep space destinations will leave Earth's cocoon for months or years at a time. And a new NASA-funded study suggests that chronic radiation exposure can damage the minds of astronauts and their bodies, potentially affecting the mood of space leaflets and even their ability to think.
This can be a big deal.
"The nature of the radiation environment in space will not deter our efforts to travel to Mars, but it may be the single biggest obstacle that humanity must decide to travel beyond Earth's orbit," researchers wrote in their study conclusion , which was published on August 5th in the journal ENeuro.
Dr. Munchal Acharya, a radiation oncologist at the University of California-Irvine and lead author of the study, said radiation exposure "affects cognitive function and behavior at the cellular level," adding that exposure can make it difficult for astronauts to respond unpredictably effectively. circumstances or stressful situations.
The study suggests that at least one in five astronauts sent to Mars will return with a severe deficiency in cognitive function, he said.
For the study – the first simulation of radiation astronauts will be on a mission to Mars – Acharya and his associates exposed 40 mice to radiation for six months and then tested the memory and behavior of the animals.
One test shows that mice exposed to radiation are less capable than controlling animals to notice subtle changes in their environment. Another revealed that the mice exposed to radiation are so alarming that they "freeze" in situations, causing no concern in control animals.
"This fear was so intense in them that it was still freezing," in anticipation of the electric shock that the researchers stopped delivering, said Aharia, adding that radiation appeared to be difficult for the mice to learn and to learn. adapt by weakening the connections between different regions of the animal brain.
JD Polk, NASA's chief health and medicine officer, called the new study an important contribution to understanding the potential radiation-induced risk to astronauts. But he warned against unwarranted anxiety, saying the animals in the study were exposed to higher levels of radiation than astronauts would likely experience in space.
"With the dosages that await us on a Mars mission, I do not expect a huge amount of cognitive decline for astronauts," says Polk, who is based at the headquarters of the Space Agency in Washington. "Is there a high risk that they will come back with a terrible cognitive decline and forget how to press the red enter button? No. "
But Charles Limoli, a radiation oncologist who heads the NASA Specialized Research Center at the University of California, Irvine and co-authored the new study, disputed that assessment. "I'm not sure what kind of literature Dr. Polk reads, but I don't agree with the context in which he puts our work – and I don't agree with his statements," he said in an email.
in any case, NASA is already working to limit the exposure of astronauts to upcoming missions.
The Agency is now testing a radiation protective vest designed to limit the radiation exposure of astronauts. And its new Orion spacecraft will be equipped with a radiation-sensing instrument to alert astronauts to jump into radiation – so that the crew can move to the middle of the ship and protect themselves with bags of provisions.
Orion will be used mainly for missions to the moon, but it can also be used to ferry astronauts to a spaceport orbiting the moon from where space flyers can travel to Mars aboard a larger ship known as the space ship. transport in depth. Scientists at the Langley Research Center in Hampton, Virginia, are now working to develop protection for me.
As hydrogen absorbs radiation, scientists are exploring ways to integrate hydrogen-rich materials into the structure of a spacecraft. One of the options discussed is to line the walls with water tanks. Another is to add a screen made of polyethylene – the same lightweight plastic used to make water bottles.
The disadvantage of adding water or plastic to deep space ships is that it would make the spacecraft much heavier, Polk said. So scientists are exploring other solutions, such as giving the craft its own electromagnetic field that blocks radiation, a sophisticated and potentially expensive technology that Polk looks like on deflector screens familiar to Star Trek viewers.
Given the cost and weight of radiation protection, NASA does not want to know how much shielding will be required to protect astronauts. Polk said future research, including additional animal studies, could help NASA make that decision. Acharya said his team will conduct new studies to identify the exact mechanisms that drive cognitive decline to help find ways to block it.
"I don't want anyone to get cancer while on Mars," Polk said. "I don't want anyone to have radiation problems while on Mars. I want to make sure it's protected."
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