Mars Voyage Radiation: How Large Is Threat To Astronauts?
A single flight to Mars would expose an astronaut to two-thirds of what NASA considers the safe lifetime limit. Put another way, it's the rough equivalent of getting a full-body CT scan once a week for a year.
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Scientists figured out the radiation levels using data from a Radiation Assessment Detector on the Mars Science Laboratory, the spacecraft that took the Curiosity rover to Mars last year.
So where does all this radiation come from?
In space, two forms of radiation may be harmful to humans. One comes from galactic cosmic rays, caused by explosions from supernovas. The other comes from solar energetic particles, resulting from solar flares and winds. Here on Earth, we are protected from much of that radiation from our magnetic field. But visitors to the Red Planet aren't quite so lucky. The radiation can damage DNA and increase the risk of cancer.
According to NASA guidelines, an astronaut should not be exposed to more than 1,000 millisieverts of radiation in a lifetime. Based on the reading from Curiosity missions Radiation Assessment Detector, an astronaut would be exposed to 662 millisieverts on a round-trip to Mars.
That translates to a 5 percent increase in the risk of getting cancer.
"As this nation strives to reach an asteroid and Mars in our lifetimes, we're working to solve every puzzle nature poses to keep astronauts safe so they can explore the unknown and return home," said William Gerstenmaier, NASA's associate administrator for human exploration and operations. "Curiosity's RAD instrument is giving us critical data we need so that we humans, like the rover, can dare mighty things to reach the Red Planet."
The radiation estimates also don't include any exposure one would experience while hanging out on Mars, just for the back-and-forth trip. The level of radiation exposure on Mars would depend on the kind of structures a person was contained in while there. Spacecraft are designed to keep out as much radiation as possible, and presumably any man-made Martian structure would be too.
"You'd like the radiation exposure to be lower, but it is what it is," said Norm Thagard, the first American who flew on the Russian space station Mir. "Given the importance of such a mission, the mission should be done."
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