Key points from article :
3 batches of lettuce grown on International Space Station (ISS) from 2014-2016, analysed.
Relative humidity, carbon dioxide concentration and temperature controlled- same in Earth.
There were more microorganisms on ISS lettuce than on those that were grown on Earth.
Levels of nutrients between both types of lettuce was very similar.
Red romaine lettuce was used for the experiment because its seeds germinate reliably.
Kale,cabbage, among other seeds sent to ISS to be grown.
Lack of sunlight, different gravity and radiation levels in space, some of the challenges.
Research by NASA's Kennedy Space Center scientists, published in Frontiers.
