Radiation on moon's surface measured for the first time, study says

While Apollo mission astronauts carried dosimeters to the moon to measure radiation, the data was never reported.

The first systematically documented measurements of radiation on the moon were undertaken in January 2019 when China's Chang'e 4 robotic spacecraft mission landed on the far side of the Moon, according to a new study in the journal Science Advances.

Astronauts on moon missions would experience an average daily radiation dose equivalent to 1,369 microsieverts per day -- about 2.6 times higher than the International Space Station crew's daily dose, the study said.

Radiation is energy that is emitted in electromagnetic waves or particles. This includes visible light and heat (infrared radiation) that we can feel and others we can't, like X-rays and radio waves. However, astronauts face a number of potentially harmful radiation sources in space from which the Earth's atmosphere largely protects us.

These include galactic cosmic rays, sporadic solar particle events (when particles emitted by the sun become accelerated) and neutrons and gamma rays from interactions between space radiation and the lunar soil.

"The radiation levels we measured on the Moon are about 200 times higher than on the surface of the Earth and 5 to 10 times higher than on a flight from New York to Frankfurt," said Robert Wimmer-Schweingruber, a professor of physics at the University of Kiel in Germany and the corresponding author of the study that published Friday, in a statement.

"Because astronauts would be exposed to these radiation levels longer than passengers or pilots on transatlantic flights, this is a considerable exposure."

A risk of space travel

Radiation exposure is one of the major risks for astronauts' health as the chronic exposure to galactic cosmic rays (GCRs) may induce cataracts, cancer or degenerative diseases of the central nervous system or other organ systems, the study said.

"Moreover, exposure to large solar particle events in a situation with insufficient shielding may cause severe acute effects," the study added.

Scientists at NASA describe radiation as one of five hazards of human space flight and the "most menacing."

On the Artemis moon mission, when the first woman will walk on the moon in 2024, the astronauts are expected to stay on the lunar surface for a week and conduct a minimum of two moonwalks.

While astronauts have stayed on the International Space Station for a year, the ISS sits just within Earth's protective magnetic field. This means that while astronauts are exposed to radiation levels 10 times higher than on Earth, it's a smaller dose than what deep space has in store.

A Mars mission would likely take two to three years and a much higher dose of radiation.

Deep space vehicles, NASA said, will sport protective shielding, dosimetry and alerts. Research is also being conducted into pharmaceuticals that could help defend against radiation, it added.