Scientists have sent broccoli seeds coated with a healthy dose of good bacteria to space in a quest to find a viable way for astronauts at the International Space Station (ISS) to grow their own vegetables - and possibly one day on the Moon or Mars.
Six broccoli seeds were aboard the Orbital ATK Cygnus spacecraft that launched this week from Wallops Island, Virginia, as part of a space station cargo resupply mission.
Three of the seeds are travelling to space as is, while the other three were coated with two different species of bacteria, developed at the University of Washington, that can live inside crop plants and improve their growth.
These "beneficial" microbes, also called endophytes, may also help plants grow better in extreme low-gravity environments, and where nutrients or water could be lacking.
The goal of the experiment, conducted by students at Valley Christian High School in San Jose in California, is to learn how to grow vegetables in the challenging, microgravity conditions of the space station - and eventually on the Moon and Mars - as human space exploration expands.
Developed by a team of 11 students, the initial ground experiments proved successful, as the broccoli grew faster and significantly larger than the control study.
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"It would be ideal if we could grow crops for astronauts at the space station or who are lunar- or Mars-based without needing to ship potting mix or fertiliser," said Sharon Doty, a professor at University of Washington.
"We would like to be able to get plants to grow in what is available with a minimum input," Doty said.
Previous research has found that plants can better tolerate drought and other environmental stressors with the help of natural microbes that provide nutrients to their plant partners.
These specific endophytes and broccoli plants were chosen for the space flight experiment because they performed well together in greenhouse tests under growing conditions similar to Mars, where nitrogen and phosphorus are limited, Freeman said.
While a number of different vegetable growing experiments have been conducted aboard the International Space Station, this is the first that studies natural microbes to possibly help plants grow under nutrient limitations and in microgravity, he said.
"In space, plants are very stressed and don't grow or reproduce well. We want plants to grow better," said John Freeman of Intrinsyx Technologies in the US.
"We are trying broccoli because it's considered an anti-carcinogenic food source that is a good dietary candidate for deep-space explorers," said Freeman.
The microbes are first encapsulated inside a coating that covers the broccoli seeds, which protects the seeds from dehydration and allows for safe dry storage before the seeds are hydrated and grown in orbit.
When the endophyte-coated broccoli seeds reach the space station, they will be hydrated in a small plant-growth chamber that provides constant light to promote photosynthesis.
Cameras will take images of the seedlings at regular intervals, which will help the high school researchers and their mentors track overall seedling growth.
After the plants return from space, the students will measure their growth and chlorophyll content and compare the inoculated broccoli to those that were grown without microbes.
"This is the first step in what I hope becomes a really long-term research program to develop habitation on Mars and on the moon in a very efficient way using natural symbiosis instead of trying to bring chemical fertilizer to those environments," Doty said.