Fancy a salad from space?

Nasa’s experiments to grow plants in space could alter the future of food.

When growing plants in space, scientists must trick them into mimicking the behavior of plants on Earth - of turning towards a source of light. Illustration by Sarah Lazarovic

While most of us are content to potter around our backyards tending our lettuces and runner beans, the boffins at the American space agency Nasa have taken things to a whole new level by cultivating food-producing plants in space. It may sound like an outlandish exercise, but if we humans do one day exhaust our own planet’s inhabitability, astral agriculture could prove vital to the survival of our species.

The foundations for evaluating the potential for growing food in space were laid down during the 1980s, when Nasa sent tomato seeds into orbit on board the Challenger shuttle. Nothing was actually grown during the mission; this early experiment assessed the effects of deep space on seeds. (It transpires that space is actually a good place in which to store seeds, as it's dry and cold enough to keep them dormant.)

Then, in 2007, the space shuttle Endeavour blasted off from the United States, carrying millions of basil seeds bound for the International Space Station, a ­permanently manned research laboratory orbiting approximately 400 kilometres above Earth. During that mission, the astronauts Barbara Morgan (from Nasa) and Dave Williams (from the Canadian Space Agency) ­experimented with growing the seeds in special growth chambers on board the ISS, before returning them to Earth 20 days later for scientific testing.

The results of this brief investigation were encouraging: according to Nasa, the basil seeds successfully germinated within the microgravity environment of the ISS, and showed growth. In other words, the Endeavour mission to the ISS proved that it is indeed possible to grow plants in space.

Fast-forward to 2013 and Nasa’s launch of the Vegetable Production System (known as “Veggie” for short). Developed by the US-based Orbital Technologies Corporation, Veggie is a low-power plant-growth system designed to provide supplemental nourishment for astronauts on board the ISS. Gioia Massa, Nasa’s science team leader for Veggie, says the experiment represents the initial steps towards developing reliable, bio-regenerative food production systems for the likes of the ISS and long-duration space exploration missions.

“The farther and longer humans go away from Earth, the greater the need to be able to grow plants for food, atmosphere recycling and psychological benefits,” she says. “I think that plant systems will become important components of any long-duration exploration scenario.”

The sky’s the limit

If astronauts on lengthy missions could one day cultivate their own fresh and nutritional food in space, it would mean they’d be less dependent on their entire food supply being sent from Earth – a hugely expensive process. According to Howard Levine, a project scientist for the ISS and Spacecraft Processing Directorate, the cost of sending astronauts’ food into outer space is in the region of US$22,000 (Dh80,809) per kilogram.

Initially, the astronauts used the Veggie growth system to attempt to grow cosmic crops of lettuce on-board the ISS. At the same time, ground-based researchers at the ISS Environmental Simulator laboratory located at the Kennedy Space Center in Florida used the same technology and processes to grow the same plants as those being grown in the space station, to provide a control for the experiment. Whereas Nasa’s previous plant-growing experiments in space were carried out within closed and controlled environments, Veggie uses the space station’s cabin environment for temperature control and allows astronauts to “interact” with the plants, a sort of ­intergalactic green fingers ­exercise.

It’s thought that nurturing plants in space could act as a kind of psychological soother for astronauts, by “beautifying’ the sterile on-board surroundings of space stations and rendering the long periods of isolation away from Earth more manageable (and somewhat greener).

Scientists are also hopeful that future space explorers will be able to utilise this flora to recycle the air supply on board space stations, since plants help to remove carbon dioxide from the air to produce oxygen that humans can breathe.

Zero-gravity lettuce

As exciting as these futuristic farming techniques may sound, the reality is that growing plants – and potentially entire crops – in space is far from straightforward. However, thanks to programmes such as Veggie, scientists are able to explore new ways in which to simplify – as well as maximise – the space planting process.

Here on Earth (depending where on the planet we’re located), we have access to natural sunlight, rainfall and plenty of land upon which to grow our crops. Now imagine trying to grow lettuce on board a space station with its confined quarters, lack of rain, light and oxygen, extreme temperature changes, cosmic radiation and very little (or even zero) gravity. Research is increasingly focusing on the variables which are known to affect plant growth in space; for example, studies of growing plants at zero gravity are providing insights into how we could one day farm the surface of the Moon or Mars, both of which have lower levels of gravity than our own planet.

On Earth, plants tend to grow towards the source of light, the Sun, but in space, scientists must trick plants into mimicking that same behaviour. The Veggie experiment relies on overhead LEDs to provide light for photosynthesis and a sense of direction to keep the plants’ shoots moving upwards. Identifying the best soil to supply all the nutrients a plant needs without the need to add fertilisers is another important area of research, as is the optimum type of rooting material to mitigate the effects of weightlessness on plants.

Cosmic crop

On June 10 last year, the Nasa astronaut and expedition commander Steve Swanson harvested the first fresh vegetable (a crop of red romaine lettuce, known as “Veg-01”) grown from seed in the Veggie chamber system on-board the ISS. The following day, the programme’s ground-based researchers harvested the control version of Veg-01 at the Kennedy Space Center. Both crops were grown for 33 days.

Frustratingly for Swanson and his colleagues on-board the ISS, they weren’t allowed to taste-test their space-grown salad; the leaves were frozen and sent back to the Kennedy Space Center, where both crops are being analysed for microbes, antioxidants, mineral levels, and so on.

While the first batch of lettuce undergoes testing to ensure safety and nutrition, the hope is to eventually allow ISS astronauts to eat food that’s been grown right there on the station, says Massa. “Our end goal is for food production, and Veggie is our first step for Nasa to be able to achieve food-production systems for space. We’re looking at developing what we call a pick-and-eat capability for space stations within the next few years.”

Now that interstellar lettuce is potentially on Nasa’s menu, scientists are turning their attention to what other crops could grow well using Veggie; dwarf plum trees are thought to be a possibility, as well as Arabidopsis, a flowering plant related to mustard and cabbage. Elsewhere, researchers have begun to grow more varieties of plants in space, including lentils, wheat and ­soybeans.

While we’ll have to sit tight and wait for Nasa to finish evaluating the results of its Veggie programme, only time will tell if one day we’ll all be nibbling on celestial celery and munching astral aubergines. One thing is for certain, though: the potential is certainly there for plants to one day play a vital role in sustaining human life beyond the realm of Earth. Space could end up being the final frontier for our food.