Crops grown in replica Martian soil have proven to be edible by humans, which will be essential for any future attempts to colonise the planet.
Although they have already demonstrated that crops can be successfully grown in the replica soil - which is high in heavy metals, just like real Martian and Moon soil - they were concerned that the compounds could cause sickness if absorbed by the plant and deposited in its fruit.
Four of the crops out of the 10 grown were tested for heavy metal content and no concentrations were detected that would be dangerous to human health. The four crops are therefore safe to eat and, for some heavy metals, the concentrations were even lower than in comparable crops grown in conventional potting soil.
Heavy metals such as lead, cadmium and copper are known to be present in the soils. If they are taken up in the parts of the crops that may be eaten, they can make the vegetables inedible to humans.
“For radish, pea, rye and tomato we did a preliminary analysis and the results are very promising,” said ecologist Wieger Wamelink, who worked on the project.
“We can eat them and I am very curious as to how the tomatoes will taste. Unfortunately, we have not been able to test all ten crops yet, which is why we set up a crowdfunding campaign through which people can feel a genuine participation in this research.”
The radishes were found to have the highest amount of metals overall, with a relatively high amount of aluminium, iron and nickel.
It is still unknown if the contamination only comes from the outside of the plant or also from the inside. The scientists believe that if the radishes were properly washed, the content would probably have been lower.
They also said it was ‘very peculiar’ that the crops grown on earth potting soil had higher contents of lead, arsenic and copper than the Martian soil simulant.
It is still unknown if the take up of heavy metals is the same on Earth as it would be under the lower gravity conditions found on Mars and the Moon. It is likely that only research ’on site’ will answer this question.
Donors to the crowdfunding project will receive a variety of gifts depending on the amount donated. For example, those donating €500 will receive a dinner based on the harvest that will include potatoes grown in the Mars soil simulant.
Further testing of the produce will look not only at the heavy metal content, but also at vitamins, flavonoids - which play a big role in determining the taste - and alkaloids that may be poisonous.
The first crops of green beans, radishes, rocket and spinach have already been harvested and the rest, including potatoes, will soon follow.
The team will investigate if the heavy metal content is below the critical levels set by the Dutch Food agency and the US Food and Drug Administration (FDA).
Last week, the head of the European Space Agency has said that humans will not visit the surface of Mars for at least 15 years because the necessary technology has not been developed yet.