Arctic plains, Sun 84.It is 6 in the morning and the Martian Arctic dawns covered by a thin layer of frost. It’s cold. Colder than in Antarctica, than in Siberia. In the horizontal light of the sun, which rises just 22 degrees above the horizon, the filigree of the ice crystals resembles a silver carpet. Rocks covered in red hematite cast long shadows. They are a few inches tall. But in this alien and chaotic landscape on miniscule scales, they could well reach a hundred meters.
The boulders of all sizes, the sand, dust, clays and sediments of this rusty world, are exposed to a constant and high dose of cosmic radiation. Like invisible bullets, the particles pass through a thin and ineffective atmosphere and are never repelled by the shield of a magnetic field.
That radiation is our Everest on Mars. And it is emerging as the greatest enemy of any mission whose crew members contain DNA in the nuclei of their cells. Space radiation particles are different from electromagnetic radiation (X-rays or ultraviolet light). On one side are thehigh energy particles, emitted by the sun during its intense storms, which are fired at the rate of millions of kilometers per hour. Being exposed to them – even in a spacesuit – is like being naked. And its effects on the body – in the very short term – are devastating.
The other particles of concern arecosmics rays. They come from undetermined galactic sources and pose an increased risk of cancer, cataracts, and long-term reproductive defects. These particles are especially dangerous because their atomic nuclei lack electrons and are capable of penetrating many inches of solid matter. In fact, they are more energetic than their solar cousins. The Earth’s atmosphere protects against both kinds of particles. The Martian atmosphere, which is just one percent the density of Earth’s, manages to stop the particles of a solar storm, but not the cosmic rays.
The combined exposure to solar and cosmic particles is measured in something calledsieverts. Counting on the exposure during the round trips, plus the 18 months of stay on Mars, an astronaut would be exposed to a total of 1 sievert. The radiation exposure limits imposed by NASA vary between 1 and 3 sieverts, depending on the age and sex of the crew member. And that’s many X-ray lifetimes in the dentist’s chair.
The experts ofMARIE instrument, on board the orbiterMars odysssey, which is in charge of measuring the radiation of the Martian soil, they say it is a “manageable dose”, although very close to the limit. The idea, then, would be to organize the missions to coincide with periods of solar calm, every 11 years. But there is a problem: although that calendar would mean less solar radiation, it would also mean more galactic radiation, because sadly, these mega-energetic particles intensify when the sun sleeps.
In other words, do you prefer vanilla or chocolate? The answer to the dilemma will have to be a combination of radiation-repellent materials and bases buried many meters underground. And perhaps use raw material from Martian soil, such asmagnesium, to pulverize it and form a kind of concrete that, applied in thick layers, can give them more insulation. Protection during the journey would consist ofplace the astronauts in the middle of the water tanksof your spacecraft, as experts have found that hydrogen in water is one of the best protectors against particle radiation.
With electronic circuitry instead of DNA, the Phoenix robot is oblivious to these concerns. Its round solar panels avidly collect the light of this dawn, which already bathes the regolith in copper tones. It is time to start another journey.
Angela Posada-Swafford
Previous Chronicles
Phoenix sticks its finger on the sore: there is water on Mars
It’s like scraping a sidewalk
What time is it on Mars?
Confirmed: there is ice near the Martian surface
Phoenix has a furnace I came from Martian land
The art of long-distance numbers
