科学美国人60秒:Curiosity Reveals Mars Astronaut Radiation Risk

Even a perfect flight to Mars poses big health risks for astronauts. Because once they were outside Earth’s protective magnetic field, astronauts would be bombarded by radiation from cosmic rays and solar outbursts.

But a side benefit of NASA’s Curiosity rover mission is that we now know about how much radiation an interplanetary traveler would face.

“The primary objective of RAD was to characterize the radiation environment on the surface of Mars.” Donald Hassler, director of the Mars Science Laboratory Radiation Assessment Detector, or RAD, on Curiosity, at a press conference May 30th.

“But we realized about a year and a half before launch that taking measurements during the cruise phase on the way to Mars in deep space would be not so different than acting as a proxy for the radiation environment that a future human astronaut might experience in their spacecraft on their way to Mars. So we turned RAD on about 10 days after the launch of Curiosity and we took about seven months of data.”

Using that data, mission scientists calculated that a Mars round-trip would expose a person to more than 100 times the average annual exposure of someone on Earth. And, critically, the radiation dose from a Mars trip could exceed the lifetime exposure limits space agencies have established for their astronauts, increasing the chances of cancer and central nervous system damage. Their report is in the journal Science. [Cary Zeitlin et al., Measurements of Energetic Particle Radiation in Transit to Mars on the Mars Science Laboratory]

Better shielding on a manned mission would help limit the risk, from both galactic cosmic rays and energetic particles from the sun. But keep in mind that Curiosity cruised to Mars during a relatively mild period of solar activity. If the sun acted up during an unlucky flight, astronauts would need extra protection to avoid taking a solar radiation beating.

—John Matson