We Know How Much Radiation Astronauts Will Receive, But We Don’t Know How to Prevent it

The journey to Mars will subject astronauts to extended periods of exposure to radiation during their months-long travel through space. While NASA’s Artemis 1 mission lasted only a matter of weeks, it provided valuable radiation exposure data that scientists can use to predict the radiation risks for future Mars crews. The measurements not only validated existing radiation prediction models but also revealed unexpected insights about the effectiveness of radiation shielding strategies too. 

Space radiation poses one of the most significant health risks for astronauts travelling beyond Earth’s magnetic field. Unlike the radiation from medical X-rays or nuclear sources on Earth, space radiation includes high-energy galactic cosmic rays and solar particle events that can penetrate traditional shielding materials. When these particles collide with human tissue, they can damage DNA, increase cancer risk and weaken the immune system. The effects are cumulative too, with longer missions like a journey to Mars significantly increasing exposure and health risks. 

The International Space Station crews receive radiation doses similar to nuclear power plant workers due to a little protection from Earth’s magnetosphere, but astronauts traveling to Mars would face much higher exposure levels during their multi-month journey. NASA estimates that a mission to Mars could expose astronauts to radiation levels that exceed current career exposure limits, making effective radiation shielding one of the key challenges for deep space exploration.

A paper recently published by a team led by Tony C Slaba from the Langley Research Centre at NASA, they use computer models and data from on-board detectors to assess the health risk to long term space flight. The data is taken from the International Space Station (ISS,) the Orion Spacecraft, the BioSentinel CubeSat and from receivers on the surface of Mars. Collectively this data enables a full mission profile to be modelled for a Martian journey. The data was captured during the time period of the Artemis-1 mission, just under one month in duration.

Space radiation comes in two primary forms that pose risks to astronauts and spacecraft. Solar Particle Events occur during solar storms, releasing intense bursts of energetic particles from the Sun, while Galactic Cosmic Rays represent a constant stream of highly penetrating radiation from deep space. The findings enabled the team to assess current models for accuracy. They found that predictions match actual measurements to within 10-25% for the International Space Station, 4% for deep space conditions, and 10% for the Martian surface. This level of precision gives confidence in the existing models and in planning radiation protection for future missions.

They also found that, having assessed traditional shielding approaches, that they are largely ineffective against Galactic Cosmic Rays. In some cases, excessive shielding or inappropriate material choices can even amplify radiation exposure through secondary particle production. This occurs when the ‘original radiation’ creates a cascade of new particles on impact that can be more dangerous than the original radiation! They found that radiation levels vary substantially depending on location and the specific shielding configurations used! Quite the headache for engineers!

Radiation exposure is one of the greatest challenges in human space exploration. The study shows that our models for assessing radiation risk are reliable and that the ability to accurately assess those risks is crucial for protecting astronauts from serious health consequences. Having a good understanding of the risk directly influences how spacecraft are engineered, and plays a key role in mission planning for trips beyond Earth orbit. More work is needed now in the design of radiation protection systems if our space travellers are to be better protected from the long term risks posed by radiation.

Source : Validated space radiation exposure predictions from earth to mars during Artemis-I

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