THE MOON IS SAFE TO INHABIT IN THE LONG TERM

The moon can be used as a base for future space exploration. But there was always the doubt that the level of radiation, which comes from space, was high enough to cause harm to people who inhabit that star for a long time.

People hoping to inhabit the Moon have reason to be happy: China's Chang'e 4 lander has made the first detailed measurements of the intense radiation on the lunar surface and found that it is safe for human exploration. . The results give researchers a better idea of ​​how much protection future crews will need.

Until recently, there were no reliable data on the level of radiation accumulation on the surface of the Moon. Astronauts on previous missions, in the 1960s to 1970s, did carry radiation meters, but they used them throughout the trip, leaving questions about the level of radiation on the Moon's surface.

But there is renewed interest in taking such steps, with NASA's Artemis program intending to land extended-stay crews by 2024 and the China National Space Administration considering human missions sometime in the 2030s. The Chang'e 4 robot made history last year when it made landfall in the Von Kármán crater on the opposite side of the Moon, bringing with it a set of instruments for the journey.

One of them was a new dosimeter operated by Wimmer-Schweingruber and his colleagues in Germany and China. The device measured radiation rates per hour and found that astronauts would be exposed to roughly 200 times the radiation levels of people on Earth. The location of the dosimeter within the Chang'e 4 probe provides partial shielding, like an astronaut's spacesuit would for his body, so the findings are quite applicable to human explorers, says Wimmer-Schweingruber.

The metered dose is five to 10 times greater than that received by passengers on an intercontinental flight from New York City to Frankfurt, Germany, when the plane is above parts of the protective atmosphere, says Wimmer-Schweingruber. Although high by ground standards, radiation is one of the known dangers of space flight. NASA is prohibited by law from increasing the risk of its astronauts dying from cancer by more than 3%, and these levels remain below that.

Furthermore, the researchers calculated that lunar bases covered with at least 50 centimeters of lunar soil would be enough to protect them. A deeper chamber protected with about 10 meters of water would be enough to protect against occasional solar storms, which can cause radiation levels to rise dramatically. (Between the Apollo 16 and 17 missions, the Sun turned on in a way that could have caused radiation sickness, vomiting, and possibly death if the astronauts had been unprotected in space at the time.) Such a camera should be accessible in 30 minutes, the amount of advanced warning time now possible with monitoring satellites.

The specialized dosimeter measured both charged and neutral particles. Charged particles, such as protons and heavy nuclei that have been stripped of their electrons, are dangerous because they can penetrate human skin and damage DNA, causing cancer and other adverse health effects. They come from two main sources: powerful solar flares thrown sporadically at the Moon and a constant shower of galactic cosmic rays from deep space.

Unlike Earth, the Moon lacks a magnetic field to deflect this radiation. When it hits the surface, it produces a secondary spray of neutral particles, including neutrons, which can penetrate deeper than charged particles. Neutrons can crush and hit loose protons in a person's tissue, transmitting momentum like billiard balls, says Wimmer-Schweingruber. These energetic, charged protons can wreak havoc on other cells. Measurements of this neutral component did not exist before and were difficult to estimate even using sophisticated models.

The results are nothing that scientists didn't already suspect. But it is good to have the specific measures, which verify that, if astronauts live in armored bases, they can spend up to 6 months on the Moon without exceeding NASA's legally binding limits.