Aboard the ISS, French astronaut Sophie Adenot conducted the ChlorISS experiment, during which she grew plants. But in space, does a plant grow the same way as on Earth?
In space, plants have almost the same needs as on Earth to grow: water, light, air, and nutrients. Astronauts thus place the seeds in small cultivation systems specially designed to work in microgravity. Since water doesn't "fall" downward in the ISS, it can form floating bubbles.
Beforehand, on Earth, scientists must control the amount of water sent to the seeds very precisely to prevent them from drowning... or drying out.
When a seed begins to germinate, a small root comes out first. On Earth, roots grow naturally downward thanks to gravity. But in space, there is no real "up" or "down" anymore! Plants then have to use other cues to orient themselves, like light or humidity. That's why lamps are very important in space botany experiments: they serve as both a little "sun" and a compass.
Over the days, the plant develops its leaves. The process called photosynthesis begins: the plant produces its energy using light. Astronauts can then make many observations: do roots grow differently? Are leaves smaller? Does the plant produce as much oxygen as on Earth? All these experiments help us understand how life adapts in space.
This research is very useful for preparing future long missions to the Moon or Mars. One day, astronauts will likely have to grow some of their own food. Plants could also help produce oxygen, recycle water, and even improve crew morale. After all, seeing a bit of green when living in a metal station 250 miles (400 kilometers) above Earth must feel good!