Astronauts discovered that lettuces grown on board the International Space Station hold more nutritional value than ones grown on Earth.
This is a major breakthrough for future deep space missions according to microbiologists at the Kennedy Space Centre in Florida who lead the experiment.
The successful cultivation of the edible plant brings the colonisation of Mars a step closer, according to researchers from NASA.
It was planted, grown and cared for on the ISS from seeds by astronauts on the station from 2014 to 2016 as part of the Vegetable Production Systems project.
NASA says it was served by astronauts with oil and vinegar dressing and the space leaves were a wild success, described as ‘awesome’ by the crew who ate them.
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Astronauts Scott Kelly and Kjell Lindgren taste the lettuce grown onboard the ISS in August 2014. Scientists found that lettuces grown on board the International Space Station hold more nutritional value than ones grown on Earth
The lettuce grown by the ISS astronauts is a form of red romaine lettuce called Outredgeous and can take between 33 and 56 days to grow out.
‘The ability to grow food in a sustainable system that is safe for crew consumption will become critical as NASA moves toward longer missions,’ said lead author Christina Khodadad.
‘Salad-type, leafy greens can be grown and consumed fresh with few resources.’
Astronauts live on processed, pre-packaged space rations such as fruits, nuts, chocolate, shrimp cocktails, peanut butter, chicken and beef to name a few.
These have often been sterilised by heating, freeze drying, or irradiation to make them last.
Before trying the new lettuce astronauts on board the ISS had never consumed fresh food cultivated on-board.
Astronaut Steve Swanson harvests some of the crop in June 2014. The lettuce grown by the ISS astronauts is a form of red romaine lettuce called Outredgeous
They could be eaten as either youthful baby lettuces or mature upright leaves.
The ‘Veggie project’ will now see more food grown on board the internationally backed space station – such as peppers and tomatoes.
Apart from a welcome change in diet, fresh produce would provide astronauts with additional potassium as well as vitamins K, B1, and C.
These nutrients are less abundant in pre-packaged rations and tend to degrade during storage, NASA said.
When tested it turned out the lettuce grown on board the ISS is more nutritionally valuable than those planted on Earth and it was free of disease-causing bugs.
This is despite having to farm under lower gravity and more intense radiation, according to Khodadad.
The first crewed mission to Mars is planned for the late 2020s.
Humans could be living there permanently by the 2030s – and they’ll need plenty of fruit and vegetables if they want to do so sustainably.
Eating vegetables on Mars would mirror the plot in Ridley Scott’s movie The Martian in which a stranded astronaut, played by Matt Damon, grows potatoes.
He is able to stay alive long enough to be rescued by eating and rationing the potatoes he grows in the Martian soil.
Growing crops would also be timely for the upcoming Artemis-III missions to the Moon’s South pole in 2024 and Elon Musk’s SpaceX programme
The space lettuce developed undisturbed inside dedicated units for 33 to 56 days until crew members ate part of the mature leaves – with no ill effects.
The remainder was deep-frozen until transport back to Earth for chemical and biological analysis to discover their make up and nutritional value.
Astronaut Shane Kimbrough in front of the ‘Veggie’ chamber on the ISS in November 2016. The ‘Veggie project’ will now see more food grown on board the internationally backed space station – such as peppers and tomatoes
Lettuces were grown on Earth under the same conditions as a comparison.
Temperature, carbon dioxide and humidity data were logged on board the ISS, and replicated in the Kennedy Space Centre’s labs with a 24 to 48 hour delay.
In some cases, the space lettuces were richer in nutrients such as potassium, sodium, phosphorus, sulphur and zinc than the Earth lettuce.
They also had more chemical compounds called phenolics – which have proven anti-viral, anti-cancer and anti-inflammatory properties.
Space and Earth-grown lettuce had similar levels of anthocyanin and other antioxidants, which can protect cells from damage by free, reactive oxygen radicals.
There was also no difference in the microbial communities growing on the plants – including fungi and bacteria which could affect the health of the plants and their sustainability as a food source.
By mapping their DNA, the researchers found their diversity and identity were similar which they said was surprising given the unique conditions on the ISS.
They expected ISS conditions would favour the development of distinct organisms.
Researchers conducted even more tests on the lettuce and found it didn’t carry any food poisoning bugs that could contaminate crops such as E. coli and Salmonella.
The numbers of fungal and mould spores was also in the normal range for produce fit for consumption, reports Frontiers in Plant Science.
‘The International Space Station is serving as a test bed for future long-duration missions,’ said research scientist Gioia Massa.
‘These types of crop growth tests are helping to expand the suite of candidates that can be effectively grown in microgravity.
‘Future tests will study other types of leafy crops as well as small fruits like pepper and tomatoes, to help provide supplemental fresh produce for the astronaut diet.’
The encouraging results open the door for experiments with other nutritious and tasty crops onboard, to help propel astronauts further into space.
The findings of the study into the lettuce leaves has been published in the journal Frontiers in Plant Science.