Here’s How NASA Manages to Grow Chile Peppers in Space

A few weeks ago, astronauts on the International Space Station (ISS) enjoyed a very special taco feast, which included fresh Hatch peppers grown in orbit. More than a little fun for the crew, these were the first flowering plants to be grown, harvested, and consumed in space, and they represent a leap forward in the complexity of plants grown in microgravity.

To find out how fresh and tasty veggies are grown in space, we spoke to LaShelle Spencer, the project science team leader for the chili experiment, who oversaw the project from selecting and preparing the seeds to packaging for launch and remote monitoring of plants. as they grew on the ISS and supervised the first harvest.

A cozy plant environment in space.

The goal of the project was simple: to demonstrate that it is possible to grow a complex flower crop like chili peppers in space. While it is relatively easy to grow green leafy vegetables like kale on the ISS, recent projects have been successful in growing vegetables like Radishes and Wheat, growing chili peppers is more complex than these previous projects, both because the plants require careful pollination and because they take much longer to grow (around four months) compared to faster crops like lettuce and radishes.

The crops were grown in a special container on the ISS called Advanced Planet Habitat, a fully automated system that researchers on the ground can control remotely. Photos of the plants are taken within the habitat every day, and researchers can monitor many aspects of the environment, such as adjusting the red, green, and blue LED lights or the temperature inside the grow tank.


The APH is a closed environment. Compared to when you grow up in a planter, Spencer said, “You have mother nature. You have sun and the whole spectrum [of light]. “In APH, there is only a limited spectrum of light available and the plants lose UV light, causing the peppers to develop small tumors on the underside of their leaves. This is not a problem for the Hatch type of pepper plant. chosen, but may be a problem for other varieties.

Another problem is fertilization. “We use extended-release fertilizers,” Spencer explained. “We had to make sure we had the correct combination of nutrients to run in a 120-day experiment. It’s a mixture of calcium, magnesium nitrate, things like that. And when they go, they go. There is no way to add more nutrients to the system. “

Adjust conditions on the fly

While Spencer’s team had a device similar to the APH in their lab for testing, and they used it to simulate the conditions that plants required, it was still a challenge to predict exactly what conditions chili peppers would need to grow in space. “We had to adjust as we went,” he said, what they could do from the ground by modifying factors such as light levels in the habitat or clearance levels of certain chemicals from the environment.

“In microgravity, the plants had a thicker morphology. The flowers opened upwards and some of the fruits also opened upwards. “

For example, the water requirements of the plants were different on Earth than they were on the space station, which they detected by looking at photographs of the plants as they grew. “The water requirement is probably 10-15% higher than what we were doing on the ground,” Spencer explained, which was due to the way the water rested and moved around the APH in microgravity.

Plants without gravity grow strangely


Even with all these settings, there were still differences in the way the plants grew in microgravity. In the Earth’s gravity conditions, the type of chili used grows upwards, with the flowers and fruit hanging down. “In microgravity, the plants had a denser morphology and grew parallel to the scientific carrier [the tray in which the seeds are planted]. The flowers opened up and some of the fruits opened up as well, ”Spencer explained.

This difference in plant shape isn’t just a curiosity either, as it may have affected the way the plants are pollinated. Spencer’s team found that their chili crop took longer to pollinate in orbit than in the ground, and they believe this could be because, when the flowers are pointed upward, the blasts of air they use for pollination could have blown away the flower pollen. rather than shaking a downward facing flower and letting pollen mix inside the flower.

“Because the microgravity environment affects [the crew’s] taste buds have always expressed their desire for spicier foods. “

“Microgravity definitely had a huge effect on plant morphology,” he said, but microgravity doesn’t affect all plants in the same way. “We’ve been growing leafy greens at VEGGIE for a while, and when we get the right water, they do really well. There is nothing to say that they are different from what we grow in the ground. Now that we have moved to fruit crops, there is definitely a difference. “

One of the biggest differences was that the plants in space were 50% smaller than those in the ground. But the chilies they produced were still sizable, reaching up to four to five inches long.

Tasty space tacos

So why grow chili peppers? Well, for starters, they are high in vitamin C and the plants are hardy enough to grow well even in tough conditions. In addition to the nutritional aspect, the characteristic hotness of chili peppers is highly desirable among astronauts, Spencer said: “The crew, because the microgravity environment affects their taste buds, have always expressed a desire for spicier foods. They like hot sauce! “

Despite all the complexity of growing peppers, the first harvest was a great success. “It was incredible!” Spencer said. She and her team looked at photos of the pepper harvest and instructed astronaut Mark Vande Hei to choose seven to harvest. They were mostly green, with a red bell pepper. After the peppers had been carefully picked, the astronauts diced them and enjoyed them in tacos, which astronaut Megan McArther described like “Friday party!”

Friday party! After harvesting, we tasted the red and green chili. Then we complete the surveys (I have to have the data! ?). Finally, I made my best space tacos yet: Beef Fajita, Rehydrated Tomatoes and Artichokes, and HATCH CHILE!

– Megan McArthur (@Astro_Megan) October 29, 2021

A psychological boost

This points to one of the great advantages of growing fresh food in space: Not only is it good for astronauts’ physical health to eat fresh vegetables, but it is also great for their health. Mental Wellness. Psychological experiments in the field have shown that nutritious plants can generate feelings of satisfaction and pride and can help improve mood and reduce stress. The same is likely to be true for astronauts, especially considering they are in a closed environment with little access to nature.

While Spencer’s team is still waiting for data on how the astronauts felt about caring for the chili peppers (they completed a questionnaire about their experiences as part of the experiment), she said she thought the astronauts were having a positive experience when she observed them. interacting with plants. “I see emotion on their faces when I see them on cameras,” he said. “I can tell they love the way they smell.”

Astronauts can also spend time with plants between times when they perform operations like harvesting. “They were able to take off the covers and look out the window in their spare time,” Spencer said. And that turned out to be useful for the experiment as well, as one of the team members saw a plant that was developing a common problem called flower end rot during his spare time, which he then removed from cultivation.

What’s next for plants in space?

With the first full harvest, the experiment is not over yet. More chili peppers will continue to grow, and the next harvest is tentatively scheduled for November 26. Over time, some chili peppers will return to Earth, where their genetic makeup will be compared to similar chili peppers grown on Earth, and Spencer and his team conduct a nutritional analysis.

Spencer also says that there are many more questions she wants to investigate about how microgravity affects pollination and fruiting, as we are far from having a complete understanding of how lack of gravity affects these complex plants. For now, though, we’re one step closer to providing astronauts with delicious, healthy food, and learning a lot about plants in the process.

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