ISS-grown "space lettuce" is just as good as its Earthly counterparts
A few years ago, for the first time ever, astronauts ate lettuce that had been grown aboard the International Space Station (ISS). It has now been determined that the "space lettuce" was at least as nutritious as similar plants grown on Earth.
The "Outredgeous" red romaine lettuce plants were grown on the ISS over 33- to 56-day periods, between 2014 and 2016, in NASA's Vegetable Production Systems ("Veggie") zero-gravity greenhouse chamber. Among other things, that setup incorporates LED grow lights and an automated watering system.
While the group of three astronauts consumed a few leaves each, the rest of the crop was frozen for subsequent transport back to Earth. There, it was chemically and biologically analyzed by scientists at the Kennedy Space Center, who compared it to Outredgeous romaine that had been grown in the center's laboratories over the same time periods. That "Earth lettuce" was raised under conditions matching those in the Veggie chamber, including the temperature, carbon dioxide levels, and humidity.
Overall, the Earth and ISS plants were found to be quite similar in composition. In some cases, however, the space lettuce was actually richer in elements such as potassium, sodium, phosphorus, sulphur and zinc. It also contained higher levels of phenolics, which are molecules that have been shown to possess antiviral, anticancer and anti-inflammatory qualities.
Interestingly, the diversity and identity of microbes inhabiting the plants was similar for both groups – it had been assumed that the ISS lettuce would contain fewer types of organisms. And importantly, no harmful bacteria (such as E. coli or Salmonella) were found on any of the plants.
Based on these and other findings, the space lettuce was therefore declared good (and safe) to eat.
"The International Space Station is serving as a test bed for future long-duration missions, and these types of crop growth tests are helping to expand the suite of candidates that can be effectively grown in microgravity," says the Kennedy Space Center's Dr. Gioia Massa, co-author of a paper on the research. "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 paper was recently published in the journal Frontiers in Plant Science.