By Ben Liu, Tanya Hendy, and Dr Catriona Nguyen-Robertson
Royal Botanic Gardens Victoria is leading the “Growing Beyond Earth” Australian pilot, where schools collect data to help NASA discover new fresh, tasty, and nutritious foods for astronauts to grow and eat on the International Space Station (ISS). As humans increasingly explore space, we will want – and need – to bring plants with us. Plants are critical for keeping space travellers healthy on long missions: exploring deep space, on long stints on the ISS, or setting up a base on the Moon or Mars. Researchers are exploring the idea of crews growing some of their food during a mission, testing various crops and equipment to figure out how to do this without a lot of extra hardware or power. Why grow plants in space? Plants can provide many benefits, being consumed as food and creating a refreshing atmosphere for spaceflight and space exploration. Plants take in carbon dioxide in the air to produce valuable oxygen and can also help to control cabin humidity.1 In addition, the growth of fresh flowers and mini gardens can be good for the mental wellbeing of astronauts, and those aboard the ISS appreciate tending to a garden so far away from the greenery of Earth.2 As plant growth becomes more feasible in space, there is also hope that astronauts can be supplied with fresh food. Currently, astronauts on the ISS receive regular shipments of pre-packaged meals, but the quality and nutrition of this food degrade over time. As we plan to venture further out into space, people may travel for months or even years without resupply shipments. A lack of vitamin C was all it took to give sailors scurvy back in the day, and vitamin deficiencies cause several health problems. Simply packing multi-vitamin tablets will not be enough to keep astronauts healthy – they will need fresh produce. It’s not all about space. Overcoming the challenges of growing plants in space will also help us grow plants more efficiently on Earth. But growing plants in space is no easy feat One of the most immediate challenges for plant growth is the lack of sunlight in a contained environment of a space station or future base. Without light, photosynthesis comes to a halt and respiration becomes the dominant process in plants – meaning that they consume more oxygen than they produce. As on Earth, artificial lighting can be added to make up for the lack of natural sunlight. Plants typically use red and blue wavelengths of light to grow – they absorb those parts of the light spectrum, which is why they appear green, not red and blue. In addition, chemical engineer Professor Robert Jinkerson, aims to grow plants and mushrooms in complete darkness with specific nutrients that “reawaken” the chemical processes of photosynthesis.3 Another challenge is the microgravity environment. Plants are adapted to Earth’s gravity; they send their roots downwards towards water and nutrients, and their shoots upwards towards light. An early experiment on the ISS found that microgravity alters wheat plant leaf development, plant cells, and chloroplasts, the green component of leaves used in photosynthesis, but did not seem to be detrimental to plant growth overall. In fact, the wheat plants grew 10% taller compared to those on Earth.4In contrast, two generations of mustard plants grown in microgravity produced smaller seeds, but their germination rates were near normal.5Perhaps part of the reason for these differences is that seedings acclimatise to the low gravity environment by modulating expression of certain genes,6and different plants will respond differently. Fluids in space tend to form bubbles as, without gravity to tug downward, drops form the shape with the least amount of surface area, which is a sphere. One significant challenge for growing plants in microgravity is therefore providing enough water to keep them healthy without drowning them in water bubbles. Water must therefore be carefully distributed along with nutrients and air in a healthy balance around roots. What plants currently grow in space and how? NASA has a luggage-sized space garden on the ISS known as the Vegetable Production System, or Veggie. The garden is home to six plants, each growing in a “pillow” filled with a clay-based media and fertiliser. The crew members look after the plants and water them by hand, similar to caring for a window garden on Earth. Another system, the Passive Orbital Nutrient Delivery System, or Veggie PONDS, works with the Veggie platform but has a holder that automatically feeds and waters the plants. In the microgravity environment, plants use light and other environmental factors to orient and guide their growth. LEDs above the Veggie chamber glow magenta pink, shine light that is best suited for the plants’ growth – red and blue. Veggie has so far successfully grown three types of lettuce, Chinese cabbage, mizuna mustard, red Russian kale, and zinnia flowers, some of which have already been harvested and eaten by crew members. Another “garden” on the station is the Advanced Plant Habitat, which also uses LED lights and a porous clay medium for plant growth. Unlike Veggie, it is in an enclosed chamber and automated so that it does not require much day-to-day care from the crew. APH has already grown Arabidopsis thaliana (thale cress), a plant typically used as a model species in botany, and dwarf wheat. With over 180 sensors, its water distribution, atmosphere content, moisture levels, and temperature are automatically controlled and even send information to a team on the ground at the Kennedy Space Centre. How does the Growing Beyond Earth program help us grow plants in space?
The program is a collaboration between Royal Botanic Gardens Victoria, Fairchild Tropical Botanic Garden, The La Trobe Institute for Agriculture and Food and Melbourne Archdiocese of Catholic Schools and NASA, which will extend the successful Growing Beyond Earth® (GBE) program that has been running for six years in the United States. Growing Beyond Earth originated with Fairchild Botanic Garden in Florida, USA and is now in 350 middle and high schools across the US. More than 40,000 students have tested how well more than 180 varieties of edible plant seeds grow in a habitat similar to one on the space station. Seeds that grow well in the classrooms are then tested in a chamber at the Kennedy Space Centre, and ones that grow well there, are subsequently sent to the ISS. Students in the USA have successfully identified foods such as “Dragoon Lettuce” and “Extra Dwarf Pak Choi” that have gone on to become a part of the Veggie program.
How does the program work in Australia? Following the initial trial and pilot programs that have occurred across 2023, we are hopeful that the Australian version of the GBE program could take on an Australian flavour. That is, given the high nutritional content of many Australian Bush Foods, students could identify, grow and test Bush Foods in a specially designed Growth Chamber that replicates growth systems on the ISS, with support from scientists and Aboriginal Learning Facilitators at Royal Botanic Gardens Victoria. Some Bush Foods are sclerophyllous plants, which means they can grow on impoverished soils and where water is in short supply. For example, Microseris walteri (Murnong) has been used as a staple food for millions of years and is eight times more nutritious than a potato. Other potential candidates include Carpobrotus rossii (Pigface) and Tetragonia tetragonioides (Warrigal Greens). How do students contribute to the program?
Students test the potential of various plants in specially designed growth chambers that replicate those on the ISS. The chambers are fitted with lights and a fan, and will collect data around germination rate, plant size, edible mass, humidity, light and other variables. In 2023, two Victorian schools, Catholic Regional College, Caroline Springs, and Mount Lilydale Mercy College took part in the pilot program. Students from Catholic Regional College visited the Gardens in March 2023 to collect their special Growth Chambers and attended education sessions by Gardens experts about plant data collection and Aboriginal Bush Foods. What is your hope for the future growth of the program? Broadly, the program aims to attract and engage students in plant science through the unique connection between growing plants for space travel and the ever-emerging field of protected cropping. Whilst we’re hopeful that Australian students may help to identify the next crop to be tested on the international space station an even longer-term outcome would simply be more students engaging in the field of plant science and positively contributing to sustainable food production in the future. In the short-term, we’re hopeful that beyond this initial 2023 pilot we can continue to offer the program to schools across Australia.
How can schools become involved?
Interested schools can subscribe to Royal Botanic Gardens Victoria’s Learning E-news atrbg.vic.gov.au to keep up to date with the program.
Ivanova, T., et al. (1997). First Successful Space Seed-to-Seed Plant Growth Experiment in the SVET-2 Space Greenhouse in 1997. Space Research Institute, Bulgarian Academy of Sciences.space.bas.bg/astro/Aerosp16/tania1.pdf
Service, R.F. (8 June 2023). Crops grown without sunlight could help feed astronauts bound for Mars, and someday supplement dinner plates on Earth. Science. science.org/content/article/crops-grown-without-sunlight-could-help-feed-astronauts-bound-mars
Stutte, G. W., et al. (2005). Microgravity effects on thylakoid, single leaf, and whole canopy photosynthesis of dwarf wheat. Planta, 223(1), 46–56.doi.org/10.1007/s00425-005-0066-2
Link, B.M., et al. (2014). Seed-to-Seed-to-Seed Growth and Development of Arabidopsis in Microgravity. Astrobiology, 14(10), 866-875.doi.org/10.1089/ast.2014.1184
Medina, F., et al. (2022). Red Light Enhances Plant Adaptation to Spaceflight and Mars g-Levels. Life, 12(10), 1484.doi.org/10.3390/life12101484
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