Formidable radiation dangers in travel to Mars

Missions to Mars Shouldn’t Exceed Four Years Due to Radiation Risks, Scientists SayAstronauts will experience enormous exposure to particle radiation during Mars missions, but the dangers can be mitigated. Gizmodo, By George Dvorsky 1 Sep 21

An international collaboration of scientists say it’s safe for astronauts to fly to Mars and back, provided the length of the mission does not exceed four years and that crewed flights to the Red Planet coincide with a well-known solar cycle.

Space can kill you in all sorts of different ways, with particle radiation being among the most serious hazards. Small doses of ionizing radiation aren’t the problem—it’s the long-term exposure that’ll get you. The deleterious effects of particle radiation are cumulative, leading to health conditions such as cancer, a damaged nervous system, cataracts, radiation sickness, and reproductive issues that can influence the health of offspring.

These risks are of obvious relevance when it comes to planning of a crewed trip to Mars, as NASA is doing right now. The current plan is to send American astronauts to the Red Planet in just 12 years, so it’s important that NASA understands the ways in which it can protect its crew.

“This would only result in the cost of capital for clean energy projects in Australia remaining more expensive than other advanced economies,” he said.

The Investor Group of Climate Change, backed by funds managing $2 trillion of assets, said many nations had moved beyond net zero and were making more ambitious near term goals

Indeed, once in space, the astronauts won’t have Earth’s magnetosphere to protect them. Even with shielding, the crew will be exposed to solar energetic particles and galactic cosmic rays, the latter of which is particularly harmful to human health.

An international team of scientists recently investigated this topic to learn if a round-trip mission to Mars might be too dangerous for humans and if the timing of such missions could offset potential risks. Researchers from UCLA, MIT, GFZ Potsdam, and the Skolkovo Institute of Science and Technology in Moscow were involved in the study, which now appears in the science journal Space Weather.

They made their calculations by referencing models of particle radiation inside our solar system and models of how this radiation might impact human health and the state of a spacecraft. Results showed that a potential mission to the Red Planet should not exceed four years and that, “while space radiation imposes strict limitations and presents technological difficulties for the human mission to Mars, such a mission is still viable,” write the researchers in their study.

…… Missions to Mars lasting more than four years will require protective measures, such as better shielding, underground habitats, and possibly even biological interventions.

The next best windows for the shortest flights to Mars will appear in 2030 and again in 2050, with both departure dates corresponding to periods of solar maximum, according to the research. Interestingly, “for the previous solar cycle, the smallest effective dose would have been accumulated for a flight starting in 2000, during solar max,” write the scientists.

Another key finding of the study has to do with the thickness of the spacecraft’s protective shielding. The researchers found that thick shielding would protect the crew—but only to a point. Beyond a certain threshold of thickness, the shielding would only serve to amplify the incoming radiation, which it would do by bouncing the radiation around inside the spacecraft. Aluminum shielding at the designated optimal thickness would expose astronauts to 0.5 Sieverts during missions lasting 1.9 years, while the maximum allowable career dose for astronauts of 1 Sieverts would be accumulated after a flight lasting 3.8 years, according to the study, co-authored by Yuri Shprits, a geophysicist at UCLA.

As the researchers admit, however, their analysis was limited to aluminum shielding. “Composite materials including hydrogen-rich composites have often been discussed for use in deep space habitats,” they write. “Materials such as a carbon composite with significant hydrogen content may potentially improve shielding and allow for longer flight times, as materials containing light elements result in lower fluxes of secondary [i.e. bounced] particles.”

So this is really good news, but it shows how much work still needs to be done to protect astronauts during long-duration missions. The new paper doesn’t even get into the deleterious effects of microgravity, which is also very bad for human health. We’re highly motivated when it comes to exploring and living on Mars, but making it safe will prove to be a formidable challenge. https://gizmodo.com/missions-to-mars-shouldn-t-exceed-four-years-due-to-rad-1847598717