Before you buy any real estate on Mars, you might want to consider some new measurements taken by the Curiosity rover on its way to over. Scientists long knew radiation can pose a serious health hazard to human space explorers, and these new results, published in last week’s Science, give us a better handle on potential exposures during the trips to and from the red planet.
Kudos to those science writers who recognized the importance of the paper. The Curiosity mission has gathered mountains of data, but this finding stands out since it has big implications for the future of human space flight. Still, there were a couple of questions that went unanswered.
Most stories reported the estimate that a round trip would expose astronauts to 662 millisieversts. Many repeated this number as if it should mean something to the person on the street. Like we’re all now counting our millisieverts along with our grams of carbs? Some attempted to give it meaning by equating it with a 3% increased risk of cancer.
This number was reported dutifully but nobody questioned where it came from. And yet to the public, it’s really the only meaningful number in these stories.
Shouldn’t journalists be questioning facts rather than just repeating them? What’s the uncertainty here? From reporting various stories on cancer and radiation, I’m fairly sure that much of our data comes from tracking victims of Hiroshima and Nagasaki, supplemented with medical exposures.
What are the uncertainties and limitations of our data? From Three Mile Island to Fukushima to CT scans, credentialed experts have disagreed wildly over radiation exposures and cancer risk. Could the risk of 662 milliseiverts possibly be much less serious, or much worse?
Several stories repeated one of the researchers’ statements that the total radiation was the equivalent of getting a CT scan every five to six days for the duration of the trip. This is not particularly helpful to the public. Readers might assume CT scans are quite safe, since they are common medical practice, but they can impose much more radiation than an ordinary X-ray and a number of scientists have voiced serious concerns.
There was some interesting variability in whether reporters spun the results to be bad news or a confirmation of an unfortunate reality we long understood.
Amina Khan in this Los Angeles Times story mades it sound quite dire:
Astronauts heading to Mars would face exposure to a deluge of radiation, in some cases as much as NASA policy permits, according to new data from the Curiosity rover.
In a story for the Washington Post, Joel Achenbach emphasized the long-term difficulty of the radiation problem and what this new data adds to the picture. It’s a good, honest lede and yet still intriguing.
Of all the hazards facing a human mission to Mars — something NASA and countless space buffs would love to see at some point — one of the hardest to solve is the radiation that saturates interplanetary space. New data, gathered by NASA’s Curiosity rover as it traveled to Mars, have confirmed that interplanetary space is a hostile medium and suggest that engineers need to find a way to speed up space travel significantly if they hope to reduce radiation exposure.
I noticed that he mentioned the effects of radiation on the human body and became hopeful he would explore it further.
The effects of interplanetary radiation on the human body are not well understood. Until now, scientists had limited information about how much radiation penetrates a spacecraft during an interplanetary journey. But the Curiosity rover, which bristles with instruments, carried along a Radiation Assessment Detector, and it measured the incoming radiation during its 253-day trip to Mars, which began in November 2011.
This is confusing because the Curiosity instruments measured the amount of radiation but said nothing about its effects on the human body. The story never got back to the effects on the human body.
Alicia Chang’s version of the story for AP started with the not-completely-helpful CT scan comparison. In its favor, it did at least mention that the 3% cancer risk number was not handed down from above.
Astronauts traveling to and from Mars would be bombarded with as much cosmic radiation as they would get from a full-body CT scan about once a week for a year, researchers reported Thursday.
That dose is enough to raise their cancer risk by about 3 percent, but experts caution that there are many uncertainties about the space environment’s effects on the body.
In a story at Naure.com, Ron Cowen starts dispassionately with the facts:
Astronauts travelling to Mars on any of the current space-flight vehicles would receive a dose of radiation higher than NASA standards permit, according to a study of the radiation environment inside the craft that carried the Curiosity rover to the planet.
John Timmer's story at ars Technica used the news to weigh the pros and cons of a one way ticket:
Although a private effort hopes to send some people on a one-way trip to Mars, chances are good that the first people to reach the red planet will be government-supported astronauts who will be taking a round trip. But one of NASA's own instruments has just suggested that there might be an advantage to a one-way journey: a far lower dose of radiation.
Another advantage – there’s no pollen. But on the downside I hear it’s impossible to find good sushi.
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