Galactic Gardening

Do you have issues growing plants? Many people struggle to even keep a houseplant alive, let alone a whole garden.

Countless books have been written on how to care for everything from sunflowers to trees, and one major assumption is that plants will be raised on earth.

There are no instructional books on growing plants in space, yet.

The Gilroy Lab at the University of Wisconsin-Madison is starting to write that book. Their research is teaching them not only how to grow plants in space, but how to genetically modify them for that same purpose.

When humans visit and start colonizing the moon and mars, plants will be essential for these expeditions to be self-sufficient. This may sound like science fiction to you, but governments and corporations around the world are working right now to make it happen.

“When we’re old there’s going to be to be hundreds, maybe thousands of people on the moon. People think you’re crazy right now but those people haven’t seen a rocket take off and land itself,” said Dr. Barker.

Dr. Richard Barker is an astrobotanist and Postdoctoral Research Associate in the Gilroy Lab. In this lab, researchers are investigating how plants react to environmental stress, amongst other topics. One of the practical applications of this research is observing plant behavior in one of the toughest environments imaginable: space.

Barker has been investigating how plants control their size since his doctoral program in the UK.

He came to Madison, WI to research how plants perceive and respond to gravity on earth, and stumbled across NASA to find that they were interested in this topic as well. Dr. Simon Gilroy, UW Professor of Botany and director of the Gilroy Lab, had a similar experience with his research into environmental stressors. This NASA crossover between the two topics eventually led to them working together.

In December of 2017, the Gilroy Lab sent its most recent experiment up to the International Space Station (ISS) onboard a SpaceX Falcon 9 rocket. This project was referred to as TOAST (Test of Arabidopsis Space Transcriptome) 3. The purpose of TOAST 3 was to see how the plants would grow in a reduced oxygen environment caused by microgravity.

Microgravity is not the absence of gravity, but objects do appear to be weightless. At the altitude of the International Space Station, gravity is about 90% as strong as it is at sea level. The ISS is just moving so fast that it is actually falling around the earth.This endless falling causes everything to seem weightless.

There is plenty of oxygen in the ISS, however, weird things happen in microgravity. On Earth, hot air rises. It is less dense than cold air so it expands and moves upward because of buoyancy. In microgravity, weight doesn’t matter so buoyancy doesn’t exist.

Buoyancy causes air to mix. When an organism breathes, this replaces the oxygen around them that is used up. When buoyancy stops working the mixing of air also stops. This causes pockets of low oxygen.

That can be a big issue when you are an astronaut asleep on the ISS. As you use up the oxygen around you a bubble of carbon dioxide forms around your head.

According to Dr. Barker, “NASA has solved this by inventing forced convective mixing.” They used fans.

This doesn’t really work for plants.

While air can be circulated around the leaves, the roots are in soil. To add to this challenge, water doesn’t get pulled downwards in microgravity. Instead, it coats the roots, which causes the plant to think it is in a flooded environment.

This flooded environment will actually cause stunted growth in the plants. However, this isn’t totally a bad thing.

Dr. Barker pointed out that because of the very constrained environments in spacecraft, It wouldn’t be good for plants to become overgrown. On the flip side, they aren’t useful if they’re too small.

This hypothesis was tested by the NASA APEX5 Gilroy TOAST3 spaceflight mission launched on SpaceX-13.

Arabidopsis thaliana, the lab rat of plants, was sent up to the ISS. Some of these plants were genetically modified to grow like they were in a flooded environment, even when they were not. The rest of the plants were standard Arabidopsis.

The same plants were grown here on earth. All of the modified plants and the control plants in space grew the same amount, whereas the control on earth grew faster. This supported the hypothesis of the lab.

A third type of Arabidopsis was sent up to the ISS. This one had an altered capacity to send signals within itself to counteract these flooding signals.

This was the first plant to be enhanced with the specific goal of growing better in space flight. The enhancements allowed it to grow significantly better in microgravity than either of the other types of Arabidopsis. This is the first major step to being able to engineer plants to not only grow but thrive in a microgravity environment.

Plants will of course provide a source of food on our trips beyond the atmosphere- but that’s not all. They can also be used to augment life support systems in a way that will be cheaper and more sustainable long term.

One of the ultimate goals of this research is to contribute to the creation of bioregenerative life support systems. These are like artificial ecosystems that use plants and microbes to generate oxygen, clean water, and more. Many scientists think that these will be cheaper and more efficient than the mechanical life support systems currently utilized in space travel. Not to mention the psychological benefit behind having plants and the feeling of a natural environment when you are millions of miles from earth.

This technology which has been talked about for so long in science fiction is finally on its way to becoming a reality.

Let’s grow plants in space.

Aidan Moore is a Machinery Systems Engineering undergrad at the University of Wisconsin-Madison. He will be working in the space industry after graduation. You can also read his piece on his personal website here.

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