Radiation exposure on Mars inhibits plant growth

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Tests using simulations of radiation exposure have shown that plant growth on Mars is significantly impaired. The previously preferred greenhouse solution for settlement is no longer viable.

Did Hollywood lie to us about “The Martian”? There, astronaut Mark Watney planted potatoes in Martian soil, added bacteria from a terrestrial soil sample and fertilized the plants with his excrement. He can feed on it. Experiments at the Dutch University of Wageningen now show that it is unlikely to work this way.

At first everything seemed fine. Also in Wageningen, a team of researchers has grown vegetables and herbs in Mars-like soil that NASA made based on Hawaiian volcanic sand. The harvest was no worse than on the local soil, but it was clearly contaminated with heavy metals.

A recent experiment by Wageningen scientists now shows that growing food on Mars would by no means be possible with the previously preferred global warming solution. This time, the researchers dealt with the issue of radiation exposure. This turns out to be a fundamental problem.

Because while Earth’s magnetic field and dense Earth’s atmosphere protect nature as a shield against radiation from space and thus block cosmic and solar radiation, Mars completely lacks a magnetic field and only a thin atmosphere. We already know from measurements made by the oldest rover on Mars, Curiosity, that radiation exposure on Mars averages 233 micrograms per day. This equates to 17 times the highest radiation that can be measured at Earth’s surface. In the context of a solar storm, radiation on Mars can be increased by a factor of 50.

This radiation, whether it was permanent or peak exposure, brought the Dutch research team into contact with rye and cress. The plants were planted in a lead-covered test container in regular potting soil and germinated completely normally at first. The radioactive cobalt-60 was placed in the container, spreading an equal load of about 270 μg. Some plants were also irradiated with 30 milligrams, which should mimic sporadic solar storms.

The consequences Conscious. From a positive perspective, plants that were intermittently exposed to ‘solar storms’ did not show any further degradation. However, that’s a bit of consolation, because the researchers were able to show that long-term exposure was actually enough to reduce biomass growth in garden cress plants by 32 percent and in rye by up to 48 percent. Leaf discoloration, deformities, necrosis and brown spots were also observed.

In fact – according to the researchers – a worse result cannot be ruled out because the simulations on Earth could not take into account the radiation of particularly high-energy cosmic particles. The team surrounding research leaders Weiger Wamilink of Wagengen University and Nink Tak of the Delft Reactor Institute consider this to be another significant potential for damage.

Thus the greenhouse concept could give way to an underground cultivation or one under special radiation protection covers. According to the idea of ​​wamelinks, it can be very easy to create the latter and at the same time protect people. He could imagine building a cathedral covered with chandeliers, the material of Martian soil, in which humans and plants could coexist. What is clear is that it will be more difficult than expected, and therefore will be much more expensive.