Farming in Space
As NASA plans for its first manned mission to Mars in the mid-2030s, the humans who will inhabit the planet may not be considered astronauts but farmers.
“The round trip to Mars generally takes about four and one-half years if you add in six months on the surface,” says Bruce Bugbee, a botanist at Utah State University. “Theoretically, it’s possible to bring four years’ worth of bag lunches, but that would be super expensive.”
It’s also risky to rely on a lightweight resupply rocket, because it can take up to 210 days to arrive. “To be efficient, inhabitants need to eat local, which means we need to find a way to produce food on Mars from recycled wastes,” he explains. “If we can’t, we are not going to be able to live on the Red Planet.”
DEALING WITH A DIFFERENT ECOSYSTEM
For over 30 years, Bugbee has been collaborating with NASA to develop closed systems for growing plants aboard space shuttles and on the International Space Station. Today, there are small, engineered space greenhouses that can grow nutritious plants by rigorously controlling the plant environment.
“Taking this to scale to support humans is going to be the real challenge,” says Robert Heinse, a soil scientist at the University of Idaho. “Some of these challenges are simply a question of where to get enough water and nutrients. Other challenges are unique to the space environment like cosmic radiation, lack of atmosphere, and low levels of light.”
To create the technology necessary to make longer space missions possible, NASA has tapped Utah State, along with three other universities, to be a part of CUBES (Center for Utilization of Biological Engineering in Space). The initiative, a $15 million, five-year project funded by NASA, will be led by Adam Arkin, a professor of bioengineering at the University of California at Berkeley. Utah State University, the University of California at Davis, Stanford University, Autodesk, and Physical Sciences Inc. will be partner organizations.
Utah State professors Bruce Bugbee (left) and Lance Seefeldt.
RED PLANET SOIL
Earth’s soil is a mixture of minerals, organic matter, gases, liquids, and countless organisms. The Red Planet is covered with crushed volcanic rock containing nothing living. Mars does, however, have carbon dioxide, some nitrogen in the atmosphere, and frozen water. As a first step, Bugbee’s colleague and biochemist Lance Seefeldt will study ways to convert atmospheric nitrogen to ammonia using bacteria and solar energy.
“We will also look at inoculating plants with rhizobia like we do legumes to help them fix nitrogen,” says Bugbee.
Rhizobia is one of the groups of soil bacteria that infect the roots of legumes to form root nodules. After infection, it produces nodules on the roots where they fix nitrogen gas from the atmosphere and produce a more readily useful form of nitrogen.
In order to achieve this, light is needed. Although it is more dispersed on Mars than on Earth, some light is available.
“Mars has only 60% of our light intensity at the surface, which means reduced photosynthesis,” explains Bugbee. “There is still enough light to grow crops.”
Bugbee and his colleagues also plan to use biology to figure out how to transform the dust that covers the Martian landscape into fertile cropland. “Biology is more efficient than mechanical approaches like filtering water,” he says.
Initially, the CUBES group may have to deal with toxic chemicals. “There are perchlorates in the soil, which are quite toxic to humans. We hope to develop plants that can take up toxins and clean up the soil,” Bugbee explains. “We also want to understand which toxins get into the food chain through the plant. Maybe we can grow plants that don’t absorb the perchlorates.”
Another obstacle will be figuring out how to grow food from recycled wastes in a small, closed system. “Exploring Mars means nearly perfect recycling of water, nutrients, gases, and plant parts that aren’t consumed,” he says. “We’ll start with a recycling, hydroponic system and gradually expand to include Martian soil.”
One crop that shows great promise is soybeans. “Soybeans are an important crop for Mars because of the diversity of products that can be made from them,” says Bugbee.
STRICTLY VEGAN
Because of the many limitations on Mars, would-be space travelers will have to rethink their diets. “To keep the area small, an efficient Mars diet will not include fruits or nuts from trees,” says Bugbee. “In addition, animal products are too expensive to sustain. What that means is life on Mars will be supported by a strictly vegan diet.”
Some experts suggest that those who venture to Mars should live on vitamin pills, dried food, and water. However, Bugbee says there is still much we don’t know about the long-term complications of such a limited diet. “Every day we eat products from hundreds of plants,” he says. “Most dieticians recommend a diet based on at least 100 diverse plants. NASA would like to grow only about five. The answer is somewhere in between.”
BENEFITS FOR EARTH
While the CUBES initiative is focused on deep space exploration, it also lends itself to practical Earth-based applications.
“When you conduct research, you discover a lot of things you weren’t specifically looking for,” says Bugbee. “It was originally NASA technology that made people think of developing indoor agriculture and growing plants without sunlight. It’s also the case with the sensing technology being used in drones to monitor plant health.”
Heinse adds that new observations in a totally different environment have really improved their understanding of root zone processes in a low-gravity environment.
“Root densities are much higher in space greenhouses compared with field-grown crops, and we are learning a lot about how to better manage root zones under high crop demand both for water and nutrients,” he says.
Some of these lessons are being applied to irrigated field crops to improve nitrogen efficiency and timing of pesticide application. “Nurseries and greenhouses with similar high-demand root zones are using soil-free media for root zones, which relies on a detailed understanding of physical and hydraulic properties and how these change with time,” adds Heinse.
“The spin-offs from studying an extreme case like Mars could have great value for food production on Earth,” says Bugbee. “What if we discover a new bacteria that could help Iowa corn fix nitrogen? That would be huge for Earth.”