Plants in space

It’s probably not the first thing you think about when you imagine a spacecraft hurtling towards Mars, but have you ever wondered about the astronaut’s environment? Where they get air from? How the temperature is kept at a comfortable level? What about waste products - for example, carbon dioxide expelled from breathing?

In amongst all the complicated electrical systems that you would expect to find, there is also some biological plant life…and it’s not just there for window dressing. Intrigued? So were we, so we spoke to NASA to find out more.

Jitendra Joshi works for NASA’s Explorations Systems Mission Directorate, which is in charge of putting together the next generation of space vehicles to go back to the Moon. Drawing upon his background in environmental science and engineering, his specialty is biological systems and mircrogravity, specifically in how plant life can be used to aid space missions.

How did your interest in plant life, as it relates to space, evolve?

“I had a fellowship from NASA for my doctoral thesis. NASA used to have specialised centres of research and training around the country. The one I was in charge of was biological systems for space development – development of advanced systems for life support. So, you try to mimic Earth in a very small microcosm and try to reduce the system penalty on power, mass, volume and things like that. I had my PhD in solid waste management, plants and air revitalisation using biological systems for NASA.”

Why is this of particular interest to NASA?

“It is expensive to put things in space. It costs about $10,000 to the pound. So, if you think of long duration missions (for example to Mars): Going to Mars is a six month journey, you’ve got to stay there for a year or a year and a half, and the journey back is another six months. In total you’re talking about 36 months. It takes a lot of ‘system penalty’ to revitalise the air, to keep the humidity in the cabin, to keep the temperature, to manage waste, to purify water, etc. By ‘system penalty’ I mean a congregation of the mass, the power, the volume, and the expendables. Power is free to a certain extent, but the power generation units – solar cells, etc. – they are a penalty.

On Earth you have a big buffer with oceans and land mass. You don’t have that [in space]. So, you reduce the size of that buffer and try to mimic Earth and reduce the system penalty. It doesn’t happen on a three or four month mission – you don’t break even.

Plants need a lot of infrastructure. Lighting is the biggest penalty for a plant system. If you have lighting you need a system to take care of the excess heat from sodium vapour lamps or whatever lamps you use.

If you do a break even, you need to have for a mission for about three – four years and then biological systems actually start becoming more economically feasible.“

Progress 24 Supply Vehicle Approaches the Station - Image courtesy of NASA

Considering the work that’s now going on for the International Space Station, do you think that there could ever be a sustaining food source from plant life (away from Earth) in space?

“You can’t fully close the plant loop yet. Using the station as a starting point, it is not yet designed yet to fully generate food, process food, etc. But, when we think of a lunar or a Martian base, you would take that into your architecture.

We do conduct research on plants on the station as we have to fully comprehend how things behave in microgravity. We are doing research – for example – on how fluids behave in the root zone (it doesn’t behave in the same way). We are also doing research into productivity of plants (are they as productive in space as on Earth?).”

Have any findings of research on plants in microgravity has an impact on how we cultivate plants on Earth?

“Yes, in terms of plant growth in enclosed environments. You want to reduce the system mass, you want to reduce the power penalty, you want to develop more efficient lamps which give out more light but less heat. You want to have good environmental control systems. All these have implications on Earth, and we have translated a lot of our knowledge.

LEDs, for example. NASA invested heavily in these. Plants don’t need the entire spectrum of white light from the Sun; they require light in certain ranges. Work here has improved plant efficiency. “

Given concerns over the disappearance of certain plant life from Earth (due to climate change) do you think it could be possible to preserve otherwise extinct species is space?

“It’s difficult for me to imagine that space might actually provide a more convenient place to preserve plants unless there is a big event on Earth where the whole planet becomes un-conducive to plants.

Our first step would be Mars, and then probably beyond that.

These systems require controlled environments. Right now we don’t have huge control systems for plant growth in space because of their inherent expense. It might be easier to create a greenhouse of sorts and preserve plant species on Earth because you’re not worried about radiation, pressure or sunlight to a large extent. It’s better to do it on Earth. “

You have a fascinating job; can you tell us how you got to where you are?

“I was brought up in a small village in India and went to a meagre public school there. I got my Bachelors and Masters in Microbiology and applied to schools in the United States for a PhD programme and got my PhD in environmental sciences and engineering. There is only one recipe: work hard and set your goals right and never give up.”

What do you think you’ll be working on in 10 years time?

“If I were still with NASA working on exploration, I think we would have achieved the replacement of a shuttle first, ferrying people back and forth. We would then slowly begin to develop some more reliable systems with ‘closed loop’ life support. This may not be just plants, but may be a combination of physical, chemical and biological systems, trying to achieve harmony – i.e. integration for optimisation of a system. That’s what I see us doing and that will help us guide the US vision for space exploration in terms of a sustained presence on the moon. The Moon will be a test-bed [for further exploration]. Our first step would be Mars, and then probably beyond that.”

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