What did the romaine lettuce astronauts Scott Kelly and Kjell Lindgren ate in 2015 taste like? Arugula, according to Kelly. Apparently plants and other food can taste different in space than they do on Earth.
In an interview in April 2016, Gioia Massa, the NASA project scientist for Veggie, an experiment aboard the International Space Station designed to understand how to grow food in space, said she wasn't surprised by Kelly's description.
"The plants in this group get more bitter compounds if they're under some stress," Massa said. "They were under some water stress and arugula tends to be a little more bitter than lettuce."
Other stresses plants can experience include sunlight, temperature, and moisture that are not in an ideal range; insects, and, of course, microgravity.
According to Space Station Explorers, plants produce protective chemicals in response to stress. This can sometimes hinder growth of nearby plants, prevent growth of disease-causing bacteria or even discourage something from eating it.
When red lettuce is under stress, it creates chemicals called sesquiterpene lactones. This causes the bitter taste.
However, according to Massa, this isn't necessarily a bad thing. She said having that "enhanced" flavor is "desirable" for the astronauts.
Since gravity is no longer pulling the fluids in an astronauts body toward his or her feet, it becomes more evenly distributed. That means extra fluid will be in an astronauts head and can cause a slight sinus congestion.
Additionally, that congestion can sometimes prevent smell detectors from working they way they should. Taste and smell work together to give someone a particular eating experience. If that is altered, it can effect how someone perceives aromas and flavors.
"Eating in space is like eating with a head cold," astronaut Chris Hadfield said in 2013 while aboard the space station. "You just can't taste very much. So because of this, a lot of our food tastes kind of bland."
Hadfield said this is why astronauts like "especially spicy" food in space. His "all-time" favorite food is shrimp cocktail with horseradish sauce.
So growing food in space can make it taste different and the changes our bodies undergo in space can make food taste different. These are all important items that are being researched in preparation for longer journeys beyond low-Earth orbit.
After the lettuce was produced, zinnias were grown in early 2016. The next major task for the Veggie experiment will be to grow Chinese cabbage around the end of 2017 and red robin tomatoes in 2018.
Video courtesy of NASA Johnson