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While we were eating Thanksgiving leftovers and shopping sales on Black Friday, astronauts on the International Space Station had a special taco night to celebrate their second successful chile pepper harvest.
As with the first historic chile pepper picking on October 29, NASA astronaut Mark Vande Hei had the honor of completing the longest plant experiment in the history of the space station on November 26, 137 days after it began in July.
Although 12 of the peppers will be returned to Earth, the crew, including NASA astronauts Raja Chari, Dr. Thomas Marshburn, Kayla Barron and European Space Agency astronaut Matthias Maurer, sampled some of the 26 chile peppers grown from four plants.
This experiment broke the record for feeding the most astronauts from a space-grown crop.
Plant Habitat-04 was one of the most complex plant experiments on the orbiting laboratory to date because peppers take much longer to grow than the previous experiments, which included various types of lettuce, flowering zinnias and even radishes.
“PH-04 pushed the state-of-the-art in space crop production significantly,” said Matt Romeyn, principal investigator for PH-04 from NASA’s Kennedy Space Center in Florida, in a statement. “With this experiment, we took a field cultivar (plant variety) of a Hatch chile pepper from New Mexico, dwarfed it to fit inside the plant habitat, and figured out how to productively grow the first generally recognized fruiting crop in space – all in a span of a couple years.”
During both harvests, the peppers were sanitized before the crew settled in to taste some of the red and green chiles and take surveys about the flavor and texture.
Following the initial taste test of seven peppers on October 29, NASA astronaut Megan McArthur made her “best space tacos yet: fajita beef, rehydrated tomatoes & artichokes, and HATCH CHILE!” the astronaut shared on Twitter.
The rare fresh produce means more than just some dietary variety and excitement for the astronauts. The success of this experiment also has multiple scientific implications for the future of astronaut nutrition and long-duration space missions.
“The level of excitement around the first harvest and the space tacos was unprecedented for us,” Romeyn said. “All indications are some of the fruit were on the spicier side, which is not unexpected, given the unknown effect microgravity could have on the capsaicin levels of peppers.” Capsaicin levels are used to determine the spiciness of a pepper.
Other differences were noted about the space peppers. Their growth experienced a two-week delay and their stems were completely straight, rather than the curvature they normally have when growing on Earth, “which is definitely a microgravity effect,” Romeyn said.
Growing plants in space
Humans have been living and working on the space station for 20 years. The bulk of their meals are prepackaged, though sometimes astronauts receive fresh treats from resupply missions. Those care packages, however, will be much more limited on longer deep space missions, including traveling to the moon or Mars.
The longer that packaged food is stored, the more it loses nutrients like vitamin C and vitamin K.
So far, astronauts have successfully grown 10 different crops on the space station since 2015 and had the chance to sample each one.
Peppers provide a great source of vitamin C, as well as other key nutrients, and these chile peppers tested well on Earth in environments simulating what the plants might experience on the space station.
Pepper plants self-pollinate, 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.
It took two years for researchers to settle on the Hatch chile pepper for their space experiment. The name belongs to several varieties grown in Hatch, New Mexico, and the Hatch Valley in southern New Mexico. This specific plant is a hybrid developed by New Mexico State University, combining the Hatch Sandia pepper and the traditional Española pepper of northern New Mexico.
But the space peppers can’t officially be Hatch chile peppers because they weren’t grown in Hatch Valley.
Forty-eight seeds launched in a carrier on a resupply mission to the space station in June. The carrier was placed inside the lab’s Advanced Plant Habitat, which is about the size of a microwave. The habitat can be monitored and controlled from Kennedy Space Center in Florida, including watering, lighting and turning on fans to promote pollen transfer.
Spicing things up
A side effect of life in zero gravity is that astronauts often lose some of their taste and smell, so spicy or well-seasoned foods are a favorite.
Adding fresh greens or peppers to the menu allows astronauts to liven up their regular meals. But growing and tending to the plants can also produce other benefits.
Astronauts have described the joy they get from seeing – as well as smelling and caring for – leafy green plants on the space station that remind them of Earth. The astronauts also helped hand-pollinate flowers on some of the plants.
“The biggest benefit that I’ve seen personally is the impact growing plants has on the crew,” said Nicole Dufour, PH-04’s project manager, in a statement. “They are so engaged when they are interacting with the plants, especially when it’s a crop plant like the peppers. We discovered the crew had been taking the door shade off every day to check on the plants and look at the peppers. That’s not something we asked them to do – they just wanted to because they enjoyed it so much.”
The results of this experiment could help researchers learn how fruit development occurs in the absence of gravity and mitigate challenges for future growth experiments.
Next up, they want to try growing dwarf tomatoes and new types of leafy greens, as well as legumes, herbs and microgreens.
“We went into this experiment knowing it wouldn’t be easy to grow peppers in microgravity, but this experiment was a wildly successful demonstration that we’re on the right path for space crop production,” Romeyn said.
“Veggie and APH (Advanced Plant Habitat) are both great systems, and we pushed APH to the limits with these chiles. We plan to take lessons we’ve learned and continue to test and develop a much larger variety of plants for eventual integration into the crew diet. Our goal is to enable viable and sustainable crop production for future missions as people explore the Moon and Mars.”