China grows a cotton plant on the far side of the moon in a biological first

This 3D reconstruction shows cotton leaves growing within China’s Chang’e 4 lander on the far side of the moon.

China has broken new lunar ground, successfully growing cotton on the moon for the first time. The experiment was part of the Chang’e 4 project, in which China is exploring the far side of the moon with a lander. This is the same lander that recently discovered a mysterious gel-like substance on the moon’s surface.

The cotton plant was one of several organisms encased in a mini biosphere weighing just 2.6 kilograms (5.7 lbs) with a pressure of 1 atmosphere which was aboard the lander. The organisms experienced an environment largely similar to that on Earth, however, they did have to contend with both space radiation and microgravity.

In an interview with engineering magazine IEEE Spectrum, project leader for the experiment Xie Gengxin explained more about the challenges of growing plants in the restricted environment. “The weight of the Chang’e-4 probe demanded that the weight [of the experiment] can’t exceed three kilograms,” he said. That’s why it was important to select the biological samples in the experiment carefully.

In the end, the team selected five species of biological organisms to send to the moon: Cotton seeds, potato seeds, arabidopsis seeds, yeast, and fruit-fly eggs. Most of these died quickly, but the cotton seeds sprouted and grew not one but two leaves. Although plants have been grown on the International Space Station before, this experiment marks the first time a plant has been grown on the moon.

However, despite the hardy cotton’s best efforts, the leaves died within one lunar day, which is equivalent to two weeks here on Earth. During the lunar night, the temperatures on the moon drop dramatically, and without external heating, the organisms were doomed by the cold. But in order to test whether the equipment could survive, the Chinese scientists continued the experiment for several months.

Originally, the team had wanted to send animals as part of the experiment including a small tortoise. However, this idea had to be scrapped due to the limited availability of oxygen. “Even though it is very meaningful to choose tortoise, the oxygen inside the payload can only be used for about 20 days for turtles,” Xie explained.

In future experiments, Xie and his team want to send more complex organisms including animals to the moon. They may get a chance with China’s Chang’e 6 mission, scheduled for the early 2020s.