The sending of human travelers to Mars would require scientists and engineers to overcome a series of technological and safety obstacles. One of these is the serious risk posed by particle radiation from the sun, distant stars, and galaxies. For this reason, the journey to Mars should not exceed a duration of 4 years.

Would particle radiation pose too great a threat to human life during a round-trip journey to the red planet? And could the timing of a mission to Mars help protect astronauts and the spacecraft from radiation? Answering positively to these two questions would bring humans much closer to the red planet.

Scientific community responses

In an article published (ref.) in the scientific journal Space Weather, an international team of space scientists, including researchers from UCLA, attempted to answer the two questions. The result is that human beings can travel safely to and from Mars. The indispensable conditions are that the spacecraft has sufficient shielding and that the overall journey is shorter than four years. Timing of a human mission to Mars would really make a difference. Scientists have determined that the best time for a flight to leave Earth would be, paradoxically, when solar activity is at its peak.

The scientists’ calculations demonstrate that this would provide natural protection. A spacecraft directed to Mars would be shielded from solar particles, which would deflect the most dangerous and energetic particles coming from distant galaxies. The average flight to Mars lasts about nine months, so depending on launch times and available fuel, it is plausible that a human mission could reach the planet and return to Earth in less than two years.

“This study shows that despite space radiation imposing stringent limitations on how heavy the spacecraft can be, on launch time, and on technological difficulties for human missions to Mars, such an enterprise is feasible” said Yuri Shprits, who is also head of space physics and space weather at the GFZ Research Center for Geosciences in Potsdam, Germany.

Latest recommendations for the trip to Mars

The researchers advise that the journey to Mars should not be a mission longer than 4 years. A longer journey would expose astronauts to a dangerously high amount of radiation during the round-trip. No more than four years in total even if they are assumed to have started in a relatively safer period. Additionally, they report that the main danger for such a mission would be particles from outside our solar system.

Yuri Shprits and colleagues from UCLA, MIT, the Skolkovo Institute of Science and Technology in Moscow, and the GFZ Research Center combined various geophysical models of particle radiation for a solar cycle. They studied in particular how radiation would have affected both human passengers and onboard spacecraft instrumentation. The modeling determined that having a shell of a spacecraft built with a thick material could help protect astronauts from radiation. But if the shielding is too thick, it could increase the amount of secondary radiation to which astronauts are exposed when it releases them.

Two main types of dangerous radiation in space are solar energetic particles and galactic cosmic rays. The intensity of each depends on solar activity. Activity of galactic cosmic rays is lower between six and 12 months following the peak of solar activity, while the intensity of solar energetic particles is highest during solar maximum, said Yuri Shprits.

Stefano Gallotta
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