Getting humans to Mars is increasingly a when, not if, prospect. And while NASA is planning a short-term return trip sometime in the 2030s, Dutch nonprofit Mars One is planning a permanent human colony by 2027.
The prospect of an ongoing food supply is therefore an important one. This is where Wageningen University and Research Centre in the Netherlands is helping out. A team of researchers has used facsimile Martian soil to grow some vegetables, against the day Mars pioneers are digging gardens far from home.
Under the leadership of researcher Wieger Wamelink, and building on their previous research, the team successfully grew ten different crops from soil simulants not just of Mars dirt, but of dirt found on the moon. These simulants were provided by NASA.
The vegetables, planted in April 2015 and harvested up to October 2015, included tomatoes, peas, rye, rocket, radish, leek, quinoa, chives, cress and spinach. They were cultivated in a glass house under the expectation that any Mars gardens will be covered to protect the plants from cosmic radiation.
Whether the team's improvements on its previous experiment could be replicated on Mars in exactly the same way could be achieved is dubious, but it does demonstrate that the dirt can be conditioned to support plant life.
"We used trays instead of small pots and added organic material (fresh cut grass) to the Mars and moon soil simulant," Wamelink explained in a statement. "This solved the problem we had with watering in the first experiment and also added manure to the soils."
The Mars soil simulant proved only a little less fertile than Earth soil, once fertilised. The Mars soil plants produced slightly less material than the Earth soil control crops, except for spinach, which showed poor production. The moon soil crop, however, only produced about half the material. Growing plants on the moon would be an uphill battle.
Growing plants on Mars isn't going to be smooth sailing, either. This is because Mars soil, and the Mars soil simulant, contains elements that would be very dangerous for human consumption. No one ate the harvested vegetables because further testing is required for their viability.
"The soils contain heavy metals like lead, arsenic and mercury and also a lot of iron. If the components become available for the plants, they may be taken up and find their way into the fruits, making them poisonous," Wamelink said.
"Further research on this is necessary and that is one of the reasons why a crowdfunding campaign has been started to finance the third experiment that will be all about food safety. The experiment should start in April 2016 with the growth of a new batch of crops including potatoes and beans. If the crops prove to be safe enough to eat, the funders will be invited for dinner where a 'Martian meal' will be served that includes the harvested crops; at least for those who dare!"