China’s moon plant experiment is dead… literally. The Chinese National Space Administration announced a few days ago the growth of a first cotton seed on the moon. An unprecedented feat, unfortunately short-lived. The small sprouted plant would not have survived the night and its freezing temperatures.
China’s Chang’e 4 mission, which is now ongoing on the far side of the moon, made the headlines two days ago after the announcement of a great first: a cotton seed had germinated, revealing a young shoot. This seed had survived space travel, and seemed to take advantage of the low lunar gravity as well as of the extraterrestrial radiation. The exploit was unfortunately only short. At a press conference yesterday (16 January), project manager Liu Hanlong explained that the plant had not survived the night, as reported by GBTimes.
The nights on the far side of the moon are indeed not on the sweet side. As soon as the sun goes down, temperatures fall to minus 52 degrees Celsius in the mini-biosphere, before continuing to fall. China’s lander has no onboard mechanism to maintain an ambient temperature and the plant could not survive and the other experiments may fall victim to the circumstances.
On Earth, as days get shorter and temperatures drop, the plants adapt and offer their cells sugar and other chemicals. The idea? Lower the freezing point of the water contained inside the cells. If ice crystals form, the cells can indeed be shredded. Other physiological and metabolic changes are made, always in order to tolerate the cold. But on our planet, progressive environmental changes allow plants to prepare.
This is why sudden frosts are often fatal. In addition, cotton is not particularly well adapted to the cold. However, if the lunar surface temperatures can reach 100 °C during the day, they can also quickly dive to minus 173 °C at night. These temperature differences were probably too brutal for these young shoots. Ice crystals were probably formed, shredding plants from within.
This young shoot will now break down gradually. Being sealed, it will not contaminate the lunar environment. None of the other plants in the experiment seems to have sprouted, and it remains unclear whether fly eggs, also present in the payload, have hatched.