"Best space tacos (玉米卷饼) yet," American astronaut Megan McArthur wrote on social media Twitter on Oct 30, with a photo of her smiling from ear to ear. The taco feast celebrated the first time peppers were successfully grown on the International Space Station.
"Growing colorful vegetables in space can have long— term benefits for physical and psychological health," said Matt Romeyn, project scientist at NASA, in a statement. The benefits of growing vegetables in space are obvious, but how are they grown?
Though astronauts have been growing plants in space for decades, cultivating edible (可食用的) food without the benefits of gravity and natural light has been difficult. A plant growth system called. Veggie has been used to grow plants on the space station since 2014, according to The New York Times.
The Veggie garden is about the size of a piece of luggage and typically holds six plants. Each plant grows in a "pillow" filled with clay and fertilizer. The "pillows" are important for distributing water, nutrients and air in a healthy balance around the roots. Otherwise, the roots would either drown in water or be swallowed by air because liquids in space tend to form bubbles (气泡), according to NASA.
.In the absence of gravity, plants use other environmental factors, such as light, to guide growth, LEDs above the plants produce a light suited for the plants' growth. According to NASA, Veggie typically glows (发光) pink, which enables plants to use both blue and red wavelengths more efficiently. Other spectrums of light, like greens, yellows or oranges, are less useful for plants.
So far, US astronauts have successfully grown 10 different crops, including lettuce and radish, on the space station since 2015, according to CNN.
Why pick peppers?
According to CNN, peppers were chosen for multiple reasons. Peppers provide a great source of vitamin C, as well as other key nutrients. Pepper plants self – pollinate (自授花粉的), so they are' easy to grow. And they are a pick—and— eat crop that doesn't have to be cooked. They also contain low microbial levels, .so they are safe to eat raw.