If humans are to establish viable off-world settlements, knowing how to grow food crops successfully in extra-terrestrial soils will be critical.
For decades, NASA scientists have been collaborating with technology firms and research bodies to master the challenges of growing food in space.
One such challenge is ensuring that food crops can be grown safely in the local soils on other moons and planets.
To that end, Dutch researchers have been using ‘soil simulants’ initially developed for NASA’s space program to grow grains, vegetables and herbs in a high-tech glasshouse designed to replicate the off-world protected-cropping facilities of the future.
The researchers, based at the Netherlands’ Wageningen University & Research Centre (Wageningen UR), had previously used samples of NASA Lunar and Mars soil simulants to grow food crops, with some success - however, many of the first trial crops died before reaching maturity.
This time around, the researchers planted 10 different crops, using three different substrates, with some minor modifications to the growing regime in aaimed at compensating for the first trial’s failures.
The findings of the second trial suggest that producing food crops on Martian soil – or on the moon – may be more than a sci-fi fantasy.
The 2015 trials
The second, large-scale Wageningen UR trial using NASA’s soil simulants began in April 2015, with the final harvest six months later in October.
The researchers planted vegetable, herb and grain species: tomato, chives, leek, pea, rye, radish, rocket, rye, quinoa and spinach. Seeds were sown in customised trays filled with either Mars or Lunar soil simulant, or with regular Earthly potting compost, used as a control.
As in the first trial, the plants were raised in a cutting-edge commercial-scale glasshouse facility under highly controlled conditions, with the scientists closely monitoring temperature, humidity, light conditions and under-earth (‘under-substrate’) atmosphere.
“This is because we expect that first crop growth on Mars and [the] moon will take place in underground rooms to protect the plants from the hostile environment including cosmic radiation,” Wageningen UR researcher Dr Wieger Wamelink explained.
The soil simulants
The Martian and Lunar soil simulants used by Dr Wamelink and his team were provided by NASA. They were chosen to mimic as closely as possible soils found on Mars and the moon. The Mars soil simulant originates from a Hawaiian volcano; the Lunar soil simulant from a desert in Arizona.
Both are produced for NASA by US-based company Orbital Technology (ORBITEC), a bioproducts and bioproduction systems group focused on creating “the next generation of bio-agricultural products”.
With more than two decades’ research in environmental control and life-support systems for NASA under its belt, ORBITEC’s off-world growing systems and solutions – advanced LED lighting, control systems and automation as well as the soil simulants – are designed to optimise growth, yield and productivity while minimising resource use and operational costs.
The substrates are available to interested researchers for use in experimental trials.
The Martian and Lunar soil simulants are part of NASA’s mission to grow edible crops in space, including on Mars, the moon and the International Space Station (ISS) – and, potentially, other moons and planets.
The eventual goal is to have soils, systems and technology capable of supplying interplanetary explorers and colonisers with fresh, safe, nutritious food grown on site.
Second trial successes
In the Wageningen UR scientists’ first trials using NASA Lunar and Mars soil-sims, most of the plants died before reaching maturity. Dr Wamelink said the team used what they learned from the first crop trial to tweak growing conditions this time around.
“We used trays instead of small pots, and added organic material (fresh-cut grass) to the Mars and moon soil simulant,” he explained. “This solved the problem we had with watering in the first experiment.”
The team also added manure to the soil-simulants in the second-round trials.
1. Survival rates improved for crops grown on Moon soil-simulant
Growth in crops planted in the Moon soil-simulant showed noticeable improvement in the recent Wageningen trials.
Whereas many of the plants sown in moon soil-simulant in the team’s initial trials failed to survive to maturity, those grown jn second-round trials thrived to the point where the researchers were able to harvest Moon-substrate-raised crops at the same time as crops of the same species grown in the Mars soil-simulant and ‘Earth’ potting compost.
2. Biomass in Mars soil-simuIant crops continued to match that of Earth-soil crops
In the first-round trials, biomass production was marginally lower in crops grown on the Mars soil-simulant than in equivalent ‘control’ crops raised on potting compost, but the difference was insignificant (and resulted primarily from the fact that one of the trays showed substantially less growth).
Second time around, the difference in the amount of biomass produced by crops grown on the Mars substrate and that produced by their compost-raised counterparts was likewise statistically insignificant.
“That was a real surprise to us,” Dr Wamelink said.“It shows that the Mars soil simulant has great potential when properly prepared and watered.”
3. The Moon soil-simulant produced viable crops, albeit with less biomass.
In the second round of trials, all the crops planted in Moon soil-simulant survived; however, they produced only “about half of the biomass” of equivalent crops raised on Mars and Earth substrates, said Dr Wamelink.
Despite their lower biomass, all but one Moon soil-simulant-grown vegie crop produced a viable amount of vegetation.“Only the spinach showed poor biomass production,” he said.
Will crops grown in Martian and Lunar soils be safe to eat?
Although the Wageningen UR researchers harvested several edible crops from the second round of glasshouse trials, they weren’t prepared to eat them, noted Wamelink.
“The soils contain heavy metals like lead, arsenic and mercury, and also a lot of iron,” he explained. “If the components become available for the plants, they may be taken up and find their way into the fruits, making them poisonous.”
Further research is needed, Wamelink said, to ensure crops grown in mineral-dense soils on other moons and planets won’t harm future off-world settlers.
The Wageningen team has mounted a crowdfunding campaign to finance a proposed third trial that focuses on the safety of food crops grown on Moon and Mars soil-simulants.
Provided sufficient funds are raised, the third wave of trials is due to start in the Northern Hemisphere spring of 2016 (Australia’s autumn), with the Wageningen scientists adding new crop species, including potatoes and beans, to the mix.
If the resulting crops prove safe for human consumption, those who helped fund the third round of trials will be invited to a celebratory dinner – a 'Martian meal' of sorts – that will feature fruits, vegetables, herbs and grains grown under simulated off-planet conditions.
For those bold enough to go ‘where no man has gone before’, it should be quite an event.
Wageningen UR team's paper, http://www.wageningenur.nl/en/Publication-details.htm?publicationId=publ... Moon mining a step closer with new lunar soil simulant. For more information, visit NASA's website and check out Facebook site Food.for.Mars.and.moon.