Extraterrestrial ecosystem

In the future, plants could play a key role in space exploration.

An “earth ship” en route to Mars would need plants to sustain life by recycling air, water and human waste, and producing oxygen and food, says Dr. Robert Ferl, distinguished professor at the University of Florida (UF) and director of the university’s Interdisciplinary Center for Biotechnology Research.

“There is very much a realization that long-term space missions — anything that lasts more than a year or two years — it’s going to be hard to take enough good food,” Ferl says. “Biological reconditioning of all of our waste and nutrients, and production of food, is really a long-term, very realistic goal of the space exploration agenda.”

There is very much a realization that long-term space missions — anything that lasts more than a year or two years — it’s going to be hard to take enough good food."

 

— Dr. Robert Ferl

As one of the two principal investigators of the UF Space Plants Lab, Ferl, who works alongside the other principal investigator, Dr. Anna-Lisa Paul, focuses on genetically engineering plants and researching them in spaceflight. In February, he and Paul returned from a trip to the EDEN ISS growing module in Antarctica. They have been in parabolic flights in aircraft; sent plants to the International Space Station (ISS) and on the Blue Origin and Virgin Galactic suborbital flights; and, every summer from 2006 through 2012, worked at the Arthur Clarke Mars Greenhouse on the uninhabited, cratered and Red Planet-esque Devon Island in the Canadian Arctic Archipelago.

By sending plants to space and studying outer space’s impact on plants, scientists such as Ferl and Paul are trying to expand our knowledge of how plants can grow in extreme environments. Ferl says understanding how plants grow in space can improve our understanding of how they grow on Earth. And if humans need or choose to colonize Mars someday, it will help with that, too.

A budding interest in sending plants to space

Ferl became intrigued by sending plants to space because of what he calls a “pretty simple” progression of events. Working in molecular biology, he tries to understand how genes work, including which genes make some plants one color versus another, and what makes some plants survive while others die.

In the mid-1990s, Ferl was studying plant tolerance to flooding and flooding gene expression. Plants were being sent into space at the time and coming back, it appeared, stressed, almost as if they had been underwater. That is when Ferl became interested in working with the space program.

“Our proximity to the Kennedy Space Center and our interest in gene expression and plants in strange environments really all coalesced in the middle to late 1990s to suggest that we can learn a lot about plants — plant reactions to environmental conditions and plant productivity — by studying plants in space,” Ferl says. “And conversely, if we learned how to grow plants in space really well, we’d learn how to feed people on extended spaceflight environments.”

Spaceflight experiments

Ferl is interested in questions addressing the limits of biology, such as if organisms can survive in space without gravity or other environmental conditions on Earth. He says it is a possibility that people will eventually colonize Mars, and by that point, astronauts will need to know how to use plants at their maximum potential.

“I’m really interested in asking the question, ‘How can we make our plants most beneficial to us, using every photon, using every electron of energy that’s produced by the system, every volume, every CO₂ molecule and everything at the most efficient way possible?’” he says. “‘What can we do with plants, to plants or around plants to make them the most efficient biological life support system available?’”

In the early 2010s, Ferl and his colleagues used digital photograph imaging to watch Arabidopsis thaliana grow on the ISS, and they made an idiosyncratic discovery. Plant roots do something called “skewing,” where they find their way through soil and avoid objects, Ferl says. In his book “The Power of Movement in Plants,” Charles Darwin wrote that roots skew because of touching other objects. However, watching roots grow on the ISS, Ferl and other scientists found the roots skewing without gravity.

“In a very real sense, although not having to do with evolution, but still in a very real sense, we proved that Darwin was wrong,” Ferl says. “How many people can in their career say that they proved Darwin wrong? So, from a very simple observation of the directionality of root growth in space we changed the way that people have to think about root growth direction choices. I think that’s pretty cool.”

In researching how plants adapt to spaceflight, Ferl and his colleagues study processes such as gene expression in roots and leaves. They consider a stressful environment one where many genes in a plant must be activated, and a less stressful environment one where fewer genes must be activated. Responses to environmental stimuli may differ between plant varieties. “Can we select for varieties that grow well in microgravity?” Ferl asks. “Can we select for varieties that will do well in spaceflight vehicles?”

“What we’re learning, quite honestly, are some really interesting biochemical facts about that adaptive process,” he says. “One of them is, for example, that plants in the absence of gravity still know how to grow their roots away from their shoots. In other words, the shoots still grow to the light but actually the roots still grow down, away from the light, because they activate genes that let them light cues for determining that architecture, instead of gravity as the determinate.”

From ice sheet to orbit

In Antarctica, the German Aerospace Center (DLR) and other public and private organizations are growing produce in a module in Antarctica via the EDEN ISS project. There, agricultural engineers monitor photons of LED lights and amp hours of battery use to determine calorie count and feed people, Ferl says.

“Our role there is to use the kind of imaging and data collection that we use on the International Space Station to monitor plant development, and especially plant health, so that we can, as a remote science backroom, help troubleshoot any issues that the plants might have,” Ferl says. “[We can] help understand how plants might be adapting differently in that environment than they would here, and [figure out] how to maximize plant productivity in that highly closed, highly engineered environment that is truly dedicated to keeping people alive.”

Most of Ferl’s work involves Arabidopsis rather than ornamental crops or produce, but he says there are parallels between greenhouse production and the type of work he does. After all, commercial growers expect a lot out of their crops and need to understand how environment affects plant growth and health. Studying what growers and farmers do, and looking at natural processes on Earth, can influence scientists who research plants in space.

He asks: “What can we learn from the productivity of our farms, our fields, our forests, our ecology, that can help us drive towards a place where we maximize truly every photon of light coming in, every molecule of nutrient, and produce the least wasteful, most beneficial, food, fiber, water and oxygen available?” Greenhouse growers may help push space exploration ahead.