Moment that mattered: China’s space agency lands a probe on the far side of the moon
The Yutu 2 moon rover sets out from the Chang’e 4 lunar probe on the far side of the moon
The Yutu 2 moon rover sets out from the Chang’e 4 lunar probe on the far side of the moon
The Chinese national space agency (CNSA) successfully landed its Chang’e 4 lunar module on the far side of the moon on 3rd January. It was the first mission of its kind – all previous lunar landings have taken place on the near side.
Andrew Coates, a UCL physics professor who works on the European Space Agency’s ExoMars rover, was impressed. “Chang’e 4 brought China to the top table of real international space power,” he says. “It’s a powerful demonstration to be able to land anywhere on the far side of the moon, with all the difficulties of communication involved.” Direct transmissions from the far side are impossible – the moon is in the way – so in May 2018 the Chinese team launched a special communication satellite, Queqiao, which relayed signals from Earth to the module from its position 65,000 kilometres beyond the moon.
Chang’e 4’s mission is to discover more about the far side of the moon. “They’re trying to understand the South Pole-Aitken basin, which is a big impact crater, and do some geophysical and solar wind interaction measurements,” says Coates. The 1,600-mile diameter, eight mile-deep South Pole-Aitken basin was chosen for touchdown because it’s thought to contain material from the moon’s interior mantle, thrown up by whatever gigantic space projectile once smashed into it with such force. To analyse samples of this mantle Chang’e 4 released a rover, Yutu 2, which has already started sending back data – although as it is solar-powered and the lunar night lasts for 14 days, it does have regular fortnight-long breaks in transmission while it goes into low power mode.
“One of the really nice things about space science is that we can transcend the political boundaries”
As well as Yutu 2, Chang’e 4 carried a temperature-regulated ‘mini lunar biosphere’ canister containing seeds from Earth and on 15th January, the People’s Daily, part of the Chinese state media, shared a photo of a cotton plant sprouting aboard the module in what it claimed was “humankind’s first biological experiment on the moon.” Sadly the cotton couldn’t stay the course. A day after the big announcement, state media broke the news that the first Earth plant to germinate on the moon had died.
“That was a very small-scale experiment just to examine whether it’s possible to grow plants on the moon,” says Coates. “Potentially it might be useful in developing moon bases, which various space agencies are now talking about. The US and Europe are working on the Deep Space Gateway, a proposed space station in orbit around the moon, which would enable some lunar science and potentially a human outpost which might eventually spread to the surface.” Surface bases could be used for extraterrestrial mining, or even for the creation of solar power stations on the moon, where panels could produce up to 40 times more electricity than their earthbound equivalents. In an early proof of concept, the Chinese government reportedly plans to launch a solar power station into orbit around the Earth by 2025.
The CNSA made use of instruments specially created for its mission by an international coalition of scientists and engineers from the Netherlands, Germany, Sweden and Saudi Arabia. “One of the really nice things about space science is that we can transcend the political boundaries, and do collaboration in space to everybody’s benefit,” says Coates.
The exorbitant cost of space exploration means that it makes sense for countries to team up and to develop complementary niches. Even countries whose politicians are at loggerheads find ways to cooperate in the final frontier. While China and the US were ramping up a tit-for-tat trade war and President Trump was accusing Chinese tech company Huawei of commercial espionage in late 2018, Nasa was working with information from CNSA to guide its Lunar Reconnaissance Orbiter to observe the Chang’e 4’s touchdown and analyse the “signature” of the plume of dust thrown up by its landing.
For all that the Chang’e 4 has brought prestige and new scientific opportunities to the Chinese, it is, says Coates, just the start. “It’s really a sort of technology demonstration,” he says. “It’s part of a phased programme to do moon landings, and then go off and land somewhere else.” The next step is Mars – and the Chinese won’t be alone. “In the planned flotilla of spacecraft going to Mars in 2020, as well as the Chinese orbiter and rover, there will be one from the UAE, the American Mars 2020 rover and the European Space Agency’s ExoMars Rover,” says Coates.
In June, India announced that it would be attempting a soft landing of a moon rover in September, which would make it only the fourth country ever – behind the US, Russia and now China – to touch down on the lunar surface. Until then, the
Yutu 2 will be alone, trundling its way across the lunar surface, a potent symbol of a nation with serious future ambitions in space.
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