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Can a tree grow in space?

The goal: a living spaceship

Tree "grows" in space
While it may seem odd to consider growing trees in space, two researchers said scientists already imitate nature for today’s satellite functions. (Illustration/Allen Davey)

Satellites and spacecraft are generally complex to build on the ground, expensive to launch and obsolete in a decade or less.

These objects end up floating in orbit around the planet contributing to the pollution surrounding the Earth. But what if there was an alternative?

That’s the question David Barnhart, director of USC’s Space Engineering Research Center and lead for the Space Systems and Technology group for the USC Information Sciences Institute, is contemplating. What if we could just “grow” spacecraft, repurpose a hybrid of inorganic and organic materials and even allow food to grow in space?

In a paper co-written with colleague and collaborator Nicole Livia Atudosiei of Bioterra Bucharest University, Barnhart discusses one alternative to creating space platforms with man-made materials coupled with the possibility of transporting food into space. He writes about what he calls “bio-terran capability in space” or “growing the environment itself.”

This could mean growing a platform for a spacecraft in outer space and/or growing the food astronauts could consume. The paper was presented last fall at the Institute of Agricultural Economics of the Romanian Academy at the Faculty of Management Agrotourism.

If we can clone sheep and land humans on the moon, we should be able to solve the challenges to grow a tree in space.

David Barnhart

“If we can clone sheep and land humans on the moon, we should be able to solve the challenges to grow a tree in space,” Barnhart said.

But why grow platforms in space instead of the traditional method of launching separate spacecraft? One issue is money. While it may cost the same to put organic and man-made materials into space, Barnhart thinks the organic materials could perhaps be repurposed once in orbit as a source of food for astronauts or as additional physical platforms that could augment future satellites.

Crazy? Out there? Wild?

Barnhart, who has worked on such successful space enterprises such as designing satlets (essentially interchangeable-Lego-like pieces that together can create a space platform of any size, shape and volume at a fraction of the cost of traditional systems), manipulative robotic arms for spacecraft and the introduction of new revenue streams for satellites, agrees.

“Peers might laugh at this idea,” Barnhart said.

Some other “out-there” ideas in their time: airplanes. A personal computer for each desk. The cellphone you hold in your hand.

For Barnhart, the idea to “grow space platforms” came out of a previous project to rethink the man-made structure of satellites and how to assemble them.

At present, satellites and space platforms are “monolithic,” that is, built out of pieces into a single entity. As such, there is no current way to modify, change, adapt or fix them once in orbit. Barnhart thought a new approach was needed.

For that project, Barnhart found inspiration in biology, coral reefs and jellyfish in particular. It led to the design of satlets, or self-contained, connectable modules, that Barnhart said will see their first flight this year. These satlets may enable some amazing new concepts, including incredibly large antenna farms and solar power stations for space.

Barnhart now envisions a space platform not manufactured on Earth and then constructed in space but one that is grown in orbit with hybrid organic and man-made materials — using a genetically modified Australian eucalyptus tree altered to withstand freezing temperatures, for example. The idea combines various disciplines at the intersection of biology, mechanics and digital systems.

“Cells are beautiful and amazing. They have the ability to attach to each other without any preconceived structural configuration, and they self-aggregate into complex systems autonomously,” Barnhart said. “How do we make the outside of currently clunky mechanical spacecraft to something like a cell that expands and contracts seamlessly, to allow more ‘cells’ to attach and grow to any size in space?”

Taking the first steps

While it may seem odd to consider growing trees in space, Barnhart and Atudosiei said scientists already imitate nature for today’s satellite functions. Heat pipes in large satellites use fluid to transfer thermal energy similar to the ways trees do for nutrient transport, for example.

While actually growing organic material openly in the vacuum and temperature of outer space is not currently possible, scientists could take initial steps toward that goal — one of which may be to grow existing species encapsulated by a material such as aerogel in a protected layer or cocoon to withstand the extreme conditions, Barnhart said.

Another idea is to engineer entirely new species of genetically modified flora and fauna that could better coexist in the extreme thermal conditions in space, with new methods to provide oxygen and nutrients.

Another benefit

Beyond cost-savings for the space program, Barnhart and Atudosiei think there could be another benefit for humans: learning how to grow in extreme conditions. As the earth experiences extreme weather conditions, such as drought and global warming, humans, they believe, must devise alternative ways to sustain life on Earth.

Such research could help us understand how to grow in austere conditions.

David Barnhart

“Such research could help us understand how to grow in austere conditions, such as growing in arid or dry conditions that haven’t traditionally been suitable for crops,” Barnhart said. “It could open up a whole new field of extreme biological technology.”

Atudosiei, whose Romanian-based lab InventiKa applies imagination to food science, believes that imagination is critical to support the world’s growing population. Without imagination, Atudosiei believes too many ideas and innovations sit “hidden in a drawer.”

Barnhart and Atudosiei have submitted a proposal to the NASA Innovative Advanced Concepts office to secure seed funding to study topics such as root growth, nutrient transport and materials that could build a cocoon. Barnhart hopes to develop prototypes to validate the first step on growing a “living spacecraft.”

“The world is just now realizing the incredible potential of ‘small’ satellites,” Barnhart said. “But they hold huge potential.”

He marvels that if we can mimic nature and translate its ability to develop complex living organisms that “aggregate” or build upon themselves and apply this strategy to spacecraft by replacing metal with organic materials, we may “just realize mankind’s first live starship.”

Barnhart chuckles when he thinks of this possibility and a question his young son asked him about the possibility of a living, breathing spaceship: “If it were alive, what would the spaceship say?”

His response? “Only time will tell …”

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