Technology

The long march of Chang’e

 By Alessandra Pierro

According to some ancient East Asian folktales, Chang’e ended up on the moon after drinking an elixir of life and remained banished there forever in company of a jade rabbit

Venerated by the Chinese as the goddess of the moon, she was interestingly mentioned during the historic Apollo 11 mission, when, during a conversation with Mission Control in Houston, the astronaut Michael Collins answered: “I was only kidding, we’ll keep a close eye out for the bunny girl”.
Fifty years later, on 3 January 2019 China made it perfectly clear that with some things there was nothing to joke about and Chang’e-4 became the first lunar exploration mission to land on the dark side of the moon.
So far, the so-called far side ‒ the side not visible from land-based observatories due to synchronised rotation ‒ had only been flown over: the very first images date back to 1959 when the unmanned Soviet mission Luna 3 photographed it and it wasn’t until 1968 that American astronauts were able to see it directly for the first time from Apollo 8.

A remarkable turnaround

The success of the Chang’e-4 mission signals a decisive moment in the Post-Cold War space race that has been opened up to space policies of countries like China whose ambitions go beyond those of the two historic contenders. Chang’e-4’s objectives include a study of the moon’s evolution and an attempt to grow plants in lunar soil.
The far side of the moon, and in particular the Von Karman crater, is of great scientific interest. This crater is one of the largest in the entire solar system and one of the oldest on the moon’s surface.

Chang'e 4 during the descent to the Moon on January 3th 2019

This is where China’s lander and rover made their landing. By studying its formation, it may be possible to date it back to the period when the asteroid bombardment hit the moon and other planets and to establish if there is a connection between this and the origins of the first lifeforms on Earth.
Furthermore, the crater is located in the moon’s south pole basin, a region where water ice has been found on the surface and where the possibility of accessible water reserves could pave the way for the idea of building the first lunar base.
The stakes continue to rise and the prospect of a race between the superpowers to get their hands on the lunar soil resources is gaining momentum.
Chinese propulsion is certainly heading in this direction. The Chang’e-4 mission has in fact already recorded another major achievement: the first biological experiment on the moon in which a plant seed succeeded in germinating.
For decades, science has been challenging itself to open up new frontiers in space farming. Both the ESA and NASA have experimented with cultivating crops in extreme conditions, demonstrating that gravity is not necessary to grow plants, and in 2015 lettuce was cultivated on board the International Space Station. But China has gone farther than anybody had ever gone before.

Survival test

The Lunar Mini Biosphere project, developed by several Chinese universities, was designed with a number of critical constraints in mind, one of which ensures the lunar soil is not contaminated with bacteria from Earth. For this reason, the lander was equipped with descent and terrain cameras in aluminium alloy where replicate a bioregenerative system to investigate the effects of radiation and lunar gravity on a complete terrestrial ecosystem and to observe the photosynthesis process in zero gravity conditions.

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Yutu-2 rover on the lunar surface (China National Space Administration/Xinhua News Agency via AP)

In this mini greenhouse, a simple biosphere was recreated with oxygen, water and sterilised soil. Yeast was then used to regulate the levels of oxygen and carbon dioxide, and fruit fly eggs were added so that the flies could act as consumers during the photosynthesis process. Lastly, the seeds of plant varieties that are very resistant to stress were planted, such as arabidopsis (a plant belonging to the broccoli family with a short growth period, thus making it easy to observe), potatoes (a possible candidate for use as a staple food during space travel) and cotton (a very resistant fibre plant).
The latter was the only seed that reacted positively and for a short time during germination, it also produced oxygen for the flies. However, as the Chinese news agency Xinuhanet announced, it wasn’t able to survive the cold temperatures of the two-week lunar night. This had been expected and although the plant didn’t survive, the experiment can nevertheless be considered a success.

A sprout on the Moon

China knows since Mao Tse-Tung’s days, that a long march starts with a small step, and this cotton sprout represents an all-time record for China in the field of extraterrestrial farming. The implications are not at all insignificant considering that, for a hypothetical future where humans can remain in space for the long term, plants would play a vital role in the production of oxygen, in air purification and in allowing a potential space community to survive autonomously, without the need for provisions from Earth.
All this would seem to suggest that China is looking to stay on the moon for a while. After all, its lunar exploration programme leaves no doubt on this score (even the logo depicts a full moon with two human footprints in the centre) and, given the forthcoming stages which have already been announced, this could happen earlier than we might think. Meanwhile, the launch of Chang’e-5 is expected before the end of the year. After a good forty years, this mission will go back to collecting lunar soil samples that will be brought back to Earth for analysis.
China’s lunar exploration programme also places the country in a leading role in terms of fostering international cooperation. The scientific payloads of Saudi Arabia, Germany, the Netherlands and Sweden contributed to the double success of Chang’e-4 and future partnerships envisage a role for Italy as well.
At this pace, one might wonder whether the international scientific community is able to find alternative solutions to addressing the survival needs of a world population in an increasing impoverishment of resources; if it is true that colonising the moon is still science fiction, it is also true that science has infinite reach.

READ MORE: Drilling on Mars by Sandeep Ravindran

about the author
Alessandra Pierro