

No one expects spacetravel to be risk-free, but we’re just beginning to learn how harsh the universe can be outside our little bubble of atmosphere. A new analysis of conditions on the moon much higher levels of radiation than expected. The Chinese-German team claims the lunar surface is so unsafe that humans will be unable to spend long periods of time there. That could certainly complicate NASA’s plans for a long-term lunar presence. 

NASA took radiation measurements on the moon back in the 1960s and 1970s during the Apollo missions. Those readings proved that astronauts could spend a few days on the surface, which is all NASA needed back then. However, it did not take daily readings to determine the maximum time someone could remain on the moon. The new study does that with the help of an experiment carried out by China’s Chang’E 4 lander in 2019.

Astronauts on the moon will encounter radiation between two and three times more intense than experienced on the International Space Station (ISS) and 200 times more intense than levels on Earth. Study co-author Robert Wimmer-Schweingruber from the University of Kiel notes that you could only hang out on the moon for two months. That takes into account the radiation you’d encounter on the week-long trip to and from the moon as well. 

The Chang’e-4 lander.

The study calls out several sources of radiation, including high-energy cosmic rays and solar particle events. Astronauts may also be bombarded by neutrons and gamma rays produced by interactions between the lunar soil and other forms of radiation. It all adds up to a much less hospitable environment than we’d hoped. By comparison, humans can live on the ISS with minimal risk for more than a year because the station is still partially protected by Earth’s magnetic field. 

Currently, NASA hopes to have humans back on the moon in 2024, and the goal is to move toward a long-term presence after that. The agency is even laying the groundwork for a space station that would remain in lunar orbit to provide crews easy access to the surface. However, extended forays to the moon will apparently require new shielding technologies. Wimmer-Schweingruber says the easiest way to make the surface safe is to build habitats with lunar soil. You’d need about 30-inches (80 cm) of soil to lower radiation levels. NASA might want to get started on that lunar sand castle technology. 

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