Quirks & Quarks

Salads in space: NASA has learned to grow lettuce on the space station

Lettuce grown on the International Space Station is just as nutritious as the stuff grown on Earth.

New study shows it’s got the same vitamins and minerals as the stuff grown on Earth

NASA astronaut Shane Kimbrough and floating red leaf lettuce on the International Space Station. (Shane Kimbrough/NASA)

Originally published on March 28, 2020.

Astronauts can now grow their own lettuce on the International Space Station, and scientists say it's as healthy as the kind grown here on Earth.

Astronaut meals typically consist of dehydrated, pre-packaged foods, but those have been shown to lose nutrients over time. Since NASA is planning long duration space flights to Mars and the lunar south pole, scientists at the Kennedy Space Center have been trying to figure out how to feed the astronauts involved. 

This lettuce is the first food grown, harvested, and eaten in space.

Just as nutritious, and delicious

The first crop of red leaf lettuce was grown on the International Space Station between 2014 and 2016. Now, in a study recently published in the journal Frontiers in Plant Science, Dr. Gioia Massa and her colleagues analyzed the lettuce and found that it contained the same amount of nutrients as the earth-grown variety. Some plants were even richer in elements like potassium, sodium, phosphorus, sulphur and zinc. 

The space lettuce was found to have higher levels of bacteria, but that's to be expected, as the space station is a warmer, closed-air system where the astronauts also work and sleep.

NASA astronaut Steve Swanson harvests a crop of red romaine lettuce plants that were grown from seed inside the ISS. (NASA)

The growing system, known as Veggie, involves vacuum-sealed seeds, pre-planted in a pillow filled with ceramic soil and fertilizer. When the astronauts were ready to start growing the lettuce, they put the pillow on a special root mat on top of a plate, bungee-cord it all down, and inject water inside. The root mat has wicks which are designed to deliver the water carefully to the plant to counteract the challenges of microgravity. 

Working toward full salads

The team started with red leaf lettuce because it's a palatable crop that's relatively easy to grow. But since then astronauts have grown different leafy greens and even flowers.

The next step will be to grow flowering plants such as peppers and tomatoes. Those will be more of a challenge, as they will require astronauts to act as bumblebees to pollinate the flowers. 

NASA astronauts Scott Kelly, Kjell Lindgren and Kimiya Yui of Japan toast with red leaf lettuce on the ISS. (NASA)

Produced and written by Amanda Buckiewicz