The astronauts aboard the International Space Station (ISS) have managed to successfully cultivate salad crop — red romaine lettuce — that is free of disease-causing microbes and safe to eat, and is at least as nutritious as Earth-grown plants.
This feat was achieved despite being grown under lowergravity and more intense radiation than on Earth.
Apart from a welcome change in diet, fresh produce wouldprovide astronauts with additional potassium as well as vitamins K, B1, and C –nutrients that are less abundant in pre-packaged rations and tend to degradeduring long-term storage.
Additionally, growing crops would be especially useful onlong-distance space missions, like the upcoming Artemis-III missions (scheduledto land humans on the lunar South pole by 2024), the current SpaceXprogramme,and NASA’s first crewed mission to Mars, planned for the late 2020s.
“The ability to grow food in a sustainable system thatis safe for crew consumption will become critical as NASA moves toward longermissions. Salad-type, leafy greens can be grown and consumed fresh with fewresources,” said Dr Christina Khodadad, a researcher at the Kennedy SpaceCenter, in a study published in the journal Frontiers in Plant Science.
Astronauts in space live on processed, pre-packaged spacerations such as fruits, nuts, chocolate, shrimp cocktails, peanut butter andchicken, etc.
These have often been sterilized by heating, freeze drying,or irradiation to make them last and key a challenge for the US Space AgencyNASA has been to figure out how to grow safe, fresh food onboard.
Between 2014-2016, lettuce was grown on board the ISS fromsurface-sterilized seeds within Vegetable Production Systems (nicknamed”Veggie”), growth chambers equipped with LED lighting and a wateringsystem, specifically designed to grow crops in space.
The crops grew undisturbed inside the Veggie units for 33 to56 days, until crew members ate part of the mature leaves (with no illeffects).
The remainder was deep-frozen until transport back to Earthfor chemical and biological analysis.
Space-grown lettuce was similar in composition to theEarth-grown controls, except that in some (but not all) trials, space-grownplant tissue tended to be richer in elements such as potassium, sodium,phosphorus, sulphur, and zinc, as well as in phenolics, molecules with provenantiviral, anticancer, and anti-inflammatory activity.
Further tests confirmed that the leaves never carried anydangerous bacteria known to occasionally contaminate crops, such as coliform E.coli, Salmonella, and S. aureus, while the numbers of fungal and mould sporeson them was also in the normal range for produce fit for human consumption.
The authors said that lettuce grown in space-borne Veggieunits is safe to eat.”The International Space Station is servingas a test bed for future long-duration missions, and these types of crop growthtests are helping to expand the suite of candidates that can be effectivelygrown in microgravity,” said DrGioia Massa, project scientist at KennedySpace Center.