Astronauts cultivate the plant on the International Space Station (ISS). The idea is to test the growth of food for long-term space missions.
What do astronauts eat when they are in space? A lot of processed, dehydrated and easy to preserve food, it is true, but since 2015 a fresh food has been available to the crew of the International Space Station: lettuce.
That’s because scientists were able to grow the plant there, and, according to a new study, the leaf is as nutritious as its terrestrial version. “The ability to grow food in a sustainable and safe system for the crew to consume will become critical as NASA moves on to longer missions. Leafy vegetables can be grown and eaten fresh with few resources,” explained Christina Khodadad, one of the researchers who analyzed the plant.
According to experts, between 2014 and 2016, lettuce was grown on board the ISS from sterile seeds, with the help of growth chambers equipped with LED lighting and an irrigation system designed specifically for space agriculture. The “crops” grew without major problems and were either consumed by astronauts or sent for analysis here on Earth.
For comparison, scientists grew lettuce here on Earth in conditions similar to those of the ISS, which was possible because the temperature, carbon dioxide and humidity data were recorded and replicated in the laboratory. The research results were shared at Frontiers in Plant Science.
According to the result, the lettuce grown by the astronauts was similar in composition to the plants on Earth, except for the fact that in some samples the vegetable tissue grown in space tended to be richer in elements such as potassium, sodium, phosphorus, sulfur and zinc, as well as phenolics – molecules with proven antiviral, anticancer and anti-inflammatory activity.
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In addition, lettuces grown in space and on Earth showed similar levels of anthocyanin and other antioxidants, which protect the plant cells.
The researchers also examined the microbial communities that grew on the plants and identified 15 microbial genera abundant in the leaves and another 20 in the roots. Surprisingly, the variety of organisms was very similar to that present on Earth’s lettuce – and of these, none is harmful to humans.
“The International Space Station is serving as a test bed for future long-term missions, and these types of crop growth tests are helping to expand the pool of candidates that can be effectively grown in microgravity,” said Gioia Massa, who also participated in the project.
“Future tests will study other types of leafy crops, as well as small fruits, such as pepper and tomatoes, to help provide fresh supplementary products for the astronaut diet,” said Massa.