The first to flourish in space was Arabidopsis thaliana, a spindly plant with white flowers, in 1982, aboard Salyut, a now defunct Russian space station. The inaugural plant species was chosen for practical reasons; scientists call Arabidopsis thaliana the fruit fly of plant science, thanks to a fairly quick life cycle that allows for many analyses in a short time.

Now, plants grow on the International Space Station, humankind’s sole laboratory above Earth. They are cultivated inside special chambers equipped with artificial lights pretending to be the sun. Seeds are planted in nutrient-rich substance resembling cat litter and strewn with fertilizer pellets. Water, unable to flow on its own, is administered carefully and precisely to roots. In microgravity, gases sometimes coalesce into bubbles, and overhead, fans push the air around to keep the carbon dioxide and oxygen flowing.

The most advanced chamber on the station, about the size of a mini fridge, has precise sensors monitoring the conditions inside, and all astronauts need to do is add water and change filters. Scientists back on the ground can control everything, from the temperature and humidity to levels of oxygen and carbon dioxide.

Plants did not evolve to exist in this unusual setup. But astronauts have grown several varieties of lettuce, radishes, peas, zinnias, and sunflowers, and they do just fine. “Plants are very adaptive, and they have to be—they can’t run away,” says Gioia Massa, a scientist at NASA’s Kennedy Space Center who studies plants in microgravity.

Scientists were surprised to learn that the lack of gravity, the force that has shaped our biological processes, doesn’t derail plants’ development. On Earth, plants produce a filigree-like pattern of roots, as they grow away from their seeds in search of nutrients. Scientists had long assumed the movements were influenced, in part, by the force of gravity. On the International Space Station, roots exhibited the same pattern, without gravity as a guide.

“Plants don’t really care about the gravity so much if you can get the environment right,” Massa says.

For NASA, the growth chambers on the space station are the predecessors of extraterrestrial farms beyond Earth. If human beings ever travel to another planet, they will need enough food for the journey. NASA has spent years perfecting thermo-stabilized or freeze-dried entrées and snacks for astronauts on the International Space Station, from scrambled eggs to chicken teriyaki. The meals are meant to last, but they wouldn’t survive the long journey to Mars, says Julie Robinson, the chief scientist for the International Space Station.

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“We don’t have a system today that would preserve all the nutrients in food for all that time, even if it was frozen,” Robinson says.