Space gardens take off

EXPERIMENT: AIMED AT ASTRONAUTS ON MISSIONS LASTING YEARS

Plants don’t need gravity to grow. They just orient themselves to the light.

It’s not easy having a green thumb in space. Without gravity, seeds can float away. Water doesn’t pour, but globs up and may drown the roots. And artificial lights and fans must be rigged just right to replicate the sun and wind.

But Nasa has decided that gardening in space will be crucial for the next generation of explorers, who need to feed themselves on missions to the Moon or Mars that may last months or years. Necessary nutrients, like vitamins C and K, break down over time in freeze-dried foods. Without them, astronauts are increasingly vulnerable to infections, poor blood clotting, cancer and heart disease.

So the US space agency has turned to professional botanists and novice gardeners, high school students, in fact, to help them practice.

“There are tens of thousands of edible plants on Earth that would presumably be useful, and it becomes a big problem to choose which of those plants are the best for producing food for astronauts,” saidd Carl Lewis, director of the Fairchild Tropical Botanic Garden, which is leading the effort. “That is where we come in.”

The Miami-based garden has identified 106 plant varieties that might do well in space, including hardy cabbages and leafy lettuces. They have enlisted 15,000 student botanists from 150 schools to grow plants in space-like conditions in their classrooms. The four-year project is about midway through, and is paid for by a $1.24 million grant from Nasa.

Using trays rigged with lights that mimic the grow boxes used in space, students tend to the plants and record data on their progress, which is shared with Nasa. In Rhys Campo’s class, the lettuce dried up. Such foibles have turned out to be a useful part of the project, said Nasa plant scientist Gioia Massa.

“If you have a plant that does well in all that variability, chances are it will do well in space.” Astronauts living at the space station 400km above Earth have encountered their share of failures while gardening in orbit, too. The first portable growing box for space, equipped with LED lights, called Veggie, was tested at the orbiting outpost in 2014. Some of the lettuce didn’t germinate. But astronauts kept trying, and took their first bite of space-grown lettuce in 2015. Now, there are two veggie grow boxes at the ISS, and a third, called the Advanced Plant Habitat.

Plants don’t need gravity to grow. They just orient themselves to the light. According to Massa, a good space plant has to be compact and produce a lot of edible food. Plants also have to do well in a spaceship like the ISS, which has a temperature of 22ºC, 40% relative humidity, and high carbon dioxide – 3 000 parts per million.

Under a system Massa said was akin to hydroponics, space plants germinate from a plant pillow with little soil, do well under LED lights and are microbially clean. Nasa is looking into robotic space gardening to automate the process. –