28 July 2021

Scientific American: “New Space Radiation Limits needed for NASA Astronauts, report says”

Everybody is planning trips to the moon and Mars, and these missions could have high radiation exposures, says Hedvig Hricak, lead author of the report and a radiologist at Memorial Sloan Kettering Cancer Center in New York City. Using current spaceflight-proved technologies, long-distance voyages—especially to the Red Planet—would exceed the proposed threshold, she says.

That could be a big problem for NASA’s Artemis program, which seeks to send astronauts to the moon in preparation for future trips to Mars. Another problem for the space agency is that the epidemiological data it uses mostly come from a longevity study of Japanese survivors of atomic bomb blasts, as well as from the handful of astronauts and cosmonauts who have endured many months or even years in low-Earth orbit. NASA’s current space radiation limit, which was developed in 2014, involves a complicated risk assessment for cancer mortality that depends on age and sex, yet more relevant data are necessary, Hricak argues. In the atomic bomb survivor study, for instance, women were more likely to develop lung cancer than men, suggesting a greater sex-based vulnerability to harmful radiation. But with the knowledge we presently have, we know we cannot make a comparison between high exposure versus chronic exposure, Hricak says. The environment is different. There are so many factors that are different.

Ramin Skibba

Another indication of NASA’s increasing risk aversion around human space flight. Setting a fixed limit for radiation exposure is a blunt solution to a very complex problem; NASA should instead concentrate efforts into finding ways to extend safe human presence in space, by researching better shielding, faster propulsion methods to reduce transit times in deep space, and treatments to prevent cancer and alleviate radiation side-effects – something that could drastically improve many lives on Earth as well! At this rate though, others will set foot on the Moon and Mars well ahead of the US – maybe Elon Musk, utterly unconcerned about the safety of travelers, possibly Jeff Bezos on the Moon, but more likely China…

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