Science

Chang’e-4 probe lands on far side of the Moon

Pictured: Previous Chang'e missions have offered a new perspective of the Moon. Source: Justin Cowart (via Flickr)

By Milo Moran

China have successfully landed the first ever robotic probe on the far side of the Moon. Chang’e-4 will study geology, listen for radio signals from space, experiment with growing plants and is being heralded as a major milestone in space exploration, not just for China but for the world.

The dark side of the Moon is relatively unexplored, with only a few probes having flown over it to take images. This is because the Moon is tidally locked, meaning one side always faces us and the other always faces away into space. The difference between the two is major: the darker patches you may see on the near side of the Moon are called “seas” and are formed by ancient volcanic activity. The far side has far fewer of these, and many more craters, as it is always exposed to space. Chang’e-4, which is named after the Chinese Moon goddess, has already sent back photographs from the surface, which have to be bounced off a satellite in order to reach Earth.

China have landed the probe in the middle of the Von Kármán crater. This depression sits within the larger South Pole-Aitken Basin, which is the result of an impact billions of years ago by something 5,000 km in diameter. The SPA Basin is huge, as wide as the distance from London to Athens. Scientists believe that this impact exposed rocks from the inner mantle of the Moon. Chang’e-4 is equipped with scientific instruments to analyse the composition of the rocks, and this will provide fascinating new data about the formation of the Moon. The far side of the Moon is also ideal for carrying out radio astronomy, because the probe will be outside the range of man-made radio interference, letting it ‘listen’ to cosmic phenomena we cannot observe from our planet.

In a major step forward, Chang’e-4 also carried cotton and potato seeds, yeast, and fruit flies. This is part of an experiment to see how biological matter fares in space, especially as the far side of the Moon regularly varies in temperature between 200 and -180°C. Growing plants on the Moon would be vital for missions to other places in the solar system, and as the first cotton seeds have sprouted, possibilities for Mars missions have been opened up.

China first sent an astronaut into orbit 15 years ago, and have since invested billions in their space project, but Caltech astronomer Ye Quanzhi said that this was the first time China has “attempted something that other space powers have not”. They seem intent on pushing further, with plans for a permanent moon settlement and a Mars lander that is scheduled for 2020. Chang’e-5 has already been lined up, but more ambitiously it will take samples of lunar rocks and soil to be returned to Earth for analysis.

We are entering a renaissance for space exploration: India are due to land on the Moon this year, SpaceX are planning space tourism by 2023, and the European Space Agency will be launching a Mars rover built in Britain and named after Rosalind Franklin.

You’d be forgiven for thinking that this is the beginning of a new ‘space race’, but this seems unlikely. Although US Vice President Mike Pence has been unveiling plans for America to advance further into space, the UK’s Professor Keith Hayward says that it’s “difficult to respond quickly – you are dealing with some very long-term plans”, making it unlikely that other countries will accelerate their programmes in response. With major international players investing large sums of money into space exploration, we can only hope that the knowledge we acquire and technology we develop are put to good use.

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