This is the latest post in my Choose-your-own-space-adventure series, where you get to vote on the next topic covered.

 

Tending to the Veggie garden on the ISS

Astronaut Steven Swanson tending to the Veggie garden on the International Space Station. Image credit: NASA

The aim of my GlutBusters project is essentially to change the way we choose the crops we grow in our kitchen gardens, moving the focus away from the ‘maximum yield’ mentality that can bring problematic gluts and ‘hungry gaps’ and towards planning for diversity rather than sheer quantity. It’s an idea that relies on a modern reality – access to crops grown on farms and commercial suppliers means that gardeners with a lack of time and/or space don’t need to aim for self-sufficiency.

But what about gardeners in space? How would they choose which crops to grow? Currently astronauts are supplied from Earth, and it’s not something they need to worry about. But it costs getting on for £14,000 to launch every kilo into space (it depends a little bit on which launch system is used), so giving astronauts the means to grow some of their own food could prove cost-effective. That’s particularly true for long duration missions, such as a crewed mission to Mars, or a lunar base. The more self-sufficient we can make the crew, the less they will need to be resupplied from Earth. However – it’s not only food they need. Plants could form a part of their life support system, removing carbon dioxide and producing oxygen, as well as recycling waste products and cleaning up waste water.

In the early 1960s, NASA began to look into the science and technology of Controlled Ecological Support Systems (CELSS), which could do all of those things. It was Boeing Company that produced the first list of suggested plants, which included 14 different crops: lettuce, Chinese cabbage, cabbage, cauliflower, kale, turnip, Swiss chard, endive, dandelion, radish, New Zealand spinach, tampala (amaranth), and sweet potato.


Crops growing in VEGGIE plant pillows
Crops tested in VEGGIE plant pillows include lettuce, Swiss chard, radishes, Chinese cabbage and peas. Image credit: NASA

There’s a lot of leafy vegetables in that list, and that’s in part due to the criteria by which they were selected. The idea was to have plants that have compact growth, so they don’t take up too much space. They need to be productive (usually ‘early’ varieties, that achieve a harvestable size quickly), and easy-to-grow. The crew don’t have much spare time to be tending veggies, nor do they have time for food processing, or space for complex machinery to do things like threshing or milling. Ideally the crops want to produce as little inedible biomass as possible, although some later versions of CELSS incorporate insects or animals that can process inedible crop wastes into edible protein.

Space veggies have to be able to cope with less-than-ideal conditions, including low light levels and problems with the water supply. The latter would be less of an issue on the Moon or Mars, where there is some gravity to ensure that irrigation water does what we need it to do and doesn’t constantly try to float off and short-circuit expensive computer equipment!

There also has to be a focus on nutritional balance, as a complete diet would be needed to keep astronauts healthy in the long term, whether all nutrients are being supplied by the CELSS, or some come from Earth-supplied rations. Home-grown food also helps to relive ‘ration fatigue’ for astronauts – fresh fruit and veg are the most eagerly awaited part of every supply run to the International Space Station. And there are psychological benefits to gardening as well, with astronauts reporting positive effects from tending plants in space.

The list of plants included in a CELSS also depends on the culture of the scientists building it, and that of the astronauts it will feed. NASA is planning on sending along lettuce, spinach, carrots, tomatoes, green onions, radishes, bell peppers, strawberries, fresh herbs and cabbages with their mission to Mars; Chinese scientists would rather go with rice, soy beans, sweet potatoes, a variety of ‘green-yellow vegetable’ (e.g. komatsuna), stem lettuce and even mulberry trees (to feed silkworms, to produce edible pupae).

And plant breeding can overcome issues with some species – a special dwarf variety of wheat (‘Apogee’, on which seed heads develop after just 23 days) was developed to be grown in space – although the technology necessary to grow plants successfully in zero gravity is still being developed.


Garden on Mars: Plants include arnica, Opium poppy and calendula
© 2007 Aggregate Industries Ltd

In 2007, garden designer Sarah Eberle won a gold medal at the Chelsea Flower Show for her interpretation of a garden that could be grown in a protected habitat in Mars. She visited Sicily to choose plant varieties that she thought might thrive in the Martian environment and that had multiple benefits, including their colour, nutrition and medicinal effects. She included coffee, wheat and calendula, with carob as a chocolate substitute. Another area of the garden was set aside for ‘luxury’ crops such as pistachios and olives, along with plants with healing properties such as arnica and the Opium poppy. If I end up going to Mars I’d like to sign up to go along with Sarah’s garden, please!

So… if you found yourself on a deserted planet, with the right kit for growing a space garden, what would you choose to grow? Let me know your thoughts in the comments!


And now its time to choose where to head next…



References
Advanced Space Transportation Program: Paving the Highway to Space

Alling, A., Van Thillo, M., Dempster, W., Nelson, M., Silverstone, S., & Allen, J. (2005). Lessons learned from Biosphere 2 and Laboratory Biosphere closed systems experiments for the Mars on Earth project. Biological Sciences in Space , 19(4), 250-260.

Farming their way to Mars: Gardeners and chefs likely to join astronauts on first trip to the Red Planet

Space-inspired garden takes top prize at UK’s Chelsea Garden Show.

Wheeler, R. M. (2011). Plants for human life support in space: From Myers to Mars. Gravitational and Space Research, 23(2).

Yu, X., Liu, H., & Tong, L. (2008). Feeding scenario of the silkworm Bombyx Mori, L. in the BLSS. Acta Astronautica, 63(7), 1086-1092.