Experiment shows: greenhouses on Mars are hardly practicable

Tests with simulated radiation exposure show that plant growth on Mars is massively impaired. The previously favored greenhouse solution for settlement no longer appears to be viable.

Did Hollywood lie to us in the movie “The Martian”? There, astronaut Mark Watney planted potatoes in the Martian soil, added bacteria from a terrestrial soil sample and fertilized the plants with his droppings. He could feed on it. Experiments by the Dutch University of Wageningen now show that it will not work that way.

Everything looked so good at first. In Wageningen, too, a team of researchers had planted vegetables and herbs in a Mars analog soil made by NASA on the basis of Hawaiian volcanic sand. The harvest was no worse than in home soil, but it was clearly contaminated with heavy metals.

The latest experiment by the Wageningen scientists now shows that the In any case, it will not be possible to grow food on Mars with the previously favored greenhouse solution. This time, the researchers have dealt with the issue of radiation exposure. And that turns out to be a fundamental problem.

Because while the earth’s magnetic field and the dense earth atmosphere shield nature as a radiation protection cover well from space and so both the Block cosmic and solar radiation, Mars completely lacks a magnetic field and the atmosphere is only thin. We already know from measurements made by the older Mars rover Curiosity that the radiation exposure on the Martian surface is on average 233 micrograys per day. This corresponds to 17 times the highest radiation that can be measured on the earth’s surface. In the course of a solar storm, the radiation on the surface of Mars can be increased by a factor of 50.

This radiation, both as a permanent as well as a peak load, the Dutch research team brought in contact with rye and cress. The plants had been sown in a lead-coated test container in ordinary potting soil and germinated initially completely normally. Radioactive cobalt-60 was placed in the container, spreading an even load of around 270 micrograys. Some plants were also irradiated with 30 milligray, which should simulate the sporadic solar storms.

The results are sobering: viewed positively, the plants that were sporadically exposed to “solar storms” showed no additional deterioration. This is little consolation, however, because the researchers were able to show that the long-term exposure had already been sufficient to reduce the growth of biomass in cress plants by 32 percent and in rye by as much as 48 percent. Discoloration of the leaves, deformations, necroses and brown spots were also observed.

In fact – according to the researchers – an even worse result cannot be ruled out because the simulation on earth could not take into account the particularly high-energy cosmic particle radiation. The team around the research manager Wieger Wamelink from the University of Wageningen and Nyncke Tack from the Delft Reactor Institute assigns a further considerable damage potential.

This could the greenhouse concept is replaced by an underground cultivation or under special radiation protection covers. According to the idea of ​​wamelinks, the latter could possibly be quite easy to construct and at the same time protect people. He could imagine building a cathedral covered with regolith, the Martian soil material, in which humans and plants could coexist. One thing is clear: It will be more difficult than hoped and therefore significantly more expensive.