Final preparations are under way for China to launch an uncrewed craft to visit both an asteroid and a comet, in the hope of learning more about the space rocks in our solar system.

The Tianwen-2 mission by the China National Space Administration (CNSA) will collect a 100-gram sample from the asteroid Kamo驶oalewa and return it to Earth. After dropping off the sample, the probe will use our planet鈥檚 gravity as a slingshot听to boost itself towards the comet 311P/PanSTARRS, which it will observe remotely.

The mission is due to launch from the Xichang Satellite Launch Center in Sichuan province . It won鈥檛 be the first to return samples of asteroids to Earth, as both NASA鈥檚 OSIRIS-REx and JAXA鈥檚 Hayabusa missions have already done that. But it will be China鈥檚 first mission to an asteroid involving the return of a rock sample, and it is likely to be the first mission to a unique type of body called a quasi-satellite.

Quasi-satellites like Kamo驶oalewa don鈥檛 strictly orbit Earth, but travel in a similar orbit to us around the sun, swinging elliptically around our planet as they do so. This unusual situation has led scientists to suspect that this particular one is a chunk of the moon ejected millions of years ago by an asteroid impact.

On the other hand, has an asteroid-like orbit 鈥� spinning around our sun in the asteroid belt between Mars and Jupiter 鈥� but with an appearance more like a comet because it has tails. These are suspected of being bits of dust and rubble flung out from its spinning body.

The CNSA that 311P/PanSTARRS is a 鈥渓iving fossil鈥�, making it useful for studying the early material composition, formation process and evolutionary history of the solar system. And Tianwen-2 will provide scientists with a better understanding of both Kamo驶oalewa and 311P/PanSTARRS. However, the results won鈥檛 come quickly: the craft is due to reach 311P/PanSTARRS in 2034, and even the Kamo驶oalewa sample is expected to return to Earth only in late 2027.

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Exactly how much the CNSA will share about the discoveries is also unclear. at the University of Birmingham, UK, says the mission鈥檚 outline is known, and one likely goal is to study the differences between the asteroid and the comet to gain a deeper understanding of the range of bodies in our solar system, but precise details haven鈥檛 been forthcoming.

Alconcel鈥檚 previous experience working with the CNSA on the leads her to suspect that the agency will hold on to the resulting scientific data tightly. 鈥淚t was extremely difficult to negotiate [with the CNSA],鈥� says Alconcel.鈥┾�漁nce they kind of had some information from us, they were not very keen to reciprocate. There will not be a public repository of this data, I don鈥檛 think.鈥�

She says that the mission is daring, as Kamo驶oalewa is spinning, which will make landing harder. Navigation algorithms are likely to demand such powerful computers that images and sensor readings will be sent back to Earth for computation. 鈥淚f we were to always pick lovely, cooperative objects, we wouldn鈥檛 learn a lot,鈥� she says. 鈥淭here鈥檚 a lot that could potentially go wrong.鈥�

The CNSA didn鈥檛 respond to 快猫短视频鈥榮 request for interview.

Dementia rates are increasing more rapidly in China than almost anywhere else in the world, with cases more than quadrupling in the country over the past few decades.

at Fudan University in China and her colleagues analysed dementia rates in 204 countries and regions around the world between 1990 and 2021. They used a World Health Organization database to collect information on dementia deaths and cases in people aged 40 and older, focusing on Alzheimer鈥檚 disease and some other forms of dementia, such as vascular dementia and frontotemporal lobe dementia.

The researchers found that the number of people with dementia worldwide more than doubled during this period, from almost 22 million in 1990 to close to 57 million in 2021. The increase was even more drastic in China, where cases more than quadrupled, rising from roughly 4 million to nearly 17 million over the same time frame.

Further analysis revealed that population growth was the main culprit. Birth rates in China spiked in the 1950s. 鈥淪o those people are getting older today 鈥� they are now in their 70s, which is the highest risk group for dementia,鈥� says at Yale University, who wasn鈥檛 involved with the study. 鈥淢any countries have baby boomers, but not as large a cohort as China鈥檚 baby boomers. So that鈥檚 the main issue.鈥�

The team identified three other major factors contributing to China鈥檚 rising dementia rates. The first, smoking, almost exclusively affects men, as only 2 per cent of women in China smoke cigarettes while . This is in sharp contrast to wealthier countries such as the US and the UK, where smoking rates have steadily declined, says Chen.

One Western trend that China has echoed is a jump in rates of diabetes and obesity, particularly in the past few decades, both of which are risk factors for dementia. This is probably because people in China are adopting a more Western diet high in fats and calories, says Chen. He believes that dementia rates in China will eventually resemble those in the US or UK, as younger generations tend to smoke less than older ones. But the condition will still have a huge impact on China in the meantime.

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鈥淒ementia is one of the most expensive diseases in the world. It requires a lot of caregiving and treatment,鈥� says Chen. 鈥淎nd in terms of an ageing population, China is still the largest in the world. There are fewer young people taking care of a larger cohort of older people with dementia. So, these are all challenges.鈥�

China鈥檚 vast electrical grid buzzes with more renewable energy than that of any other country, but this system is also becoming more vulnerable to power shortages caused by unfavourable weather. The need to ensure a reliable power supply could push China鈥檚 government to use more coal-fired power plants.

China鈥檚 energy system is rapidly getting cleaner, with virtually every month setting new records for wind and solar energy generation. The country鈥檚 overall greenhouse gas emissions 鈥� the world鈥檚 highest 鈥� are expected to soon peak and begin to decline. Wind, solar and hydropower currently make up about half of China鈥檚 power generation capacity, and are expected to increase to almost 90 per cent by 2060, when the country has pledged to reach 鈥渃arbon neutrality鈥�.

This growing reliance on renewable energy also means the country鈥檚 power system is increasingly vulnerable to changes in the weather. Intermittent wind and sun can be supplemented by steadier hydropower, produced by huge hydroelectric dams concentrated in southern China. But what happens when a wind and solar slump coincides with a drought?

at Dalian University of Technology in China and his colleagues modelled how power generation on the increasingly renewable grid would respond to these 鈥渆xtreme weather鈥� years. They estimated how the country鈥檚 current and proposed future mix of wind, solar and hydropower would behave under the least favourable weather conditions seen in the past.

They found that the future grid would be substantially more sensitive to changes in the weather than today. In the worst case weather scenario, power generation could decline by as much as 10 per cent, leading to power shortages. In 2030, a year with the least favourable weather would result in an energy shortage of more than 400 terawatt-hours, nearly 4 per cent of total energy demand. 鈥淭hat鈥檚 not a number that anyone can just ignore,鈥� says at the Asia Society Policy Institute in Washington DC.

In addition to an overall lack of power, droughts could specifically limit the amount of hydropower available to smooth out irregular wind and solar generation. This could also lead to power shortages. 鈥淚t is essential to equip the power grid with a proper proportion of stable power sources that are less affected by meteorological factors to avoid large-scale extensive electricity shortages,鈥� the researchers wrote in their paper.

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One way to help would be to move surplus electricity between provinces more efficiently. Expanding the transmission infrastructure to do so could eliminate the risk of power shortages on today鈥檚 grid and cut the risk in half by 2060, the researchers found. Adding tens of millions of kilowatts of new power capacity, whether using batteries or other methods, would also mitigate against hydropower droughts, they found.

The amount of additional storage China will need to add in order to achieve carbon neutrality 鈥渨ill be an astronomical number鈥�, says Li.

While these changes will be difficult, adding that much storage is feasible given the huge volume of batteries already being produced in China, says at the Centre for Research on Energy and Clean Air in Finland. He says the country is also building 190 gigawatts of pumped hydro power capacity, which can provide longer-term energy storage by pumping water above a dam using surplus electricity, then releasing it when more power is needed.

However, to date, power shortages have mainly spurred China鈥檚 government to build more coal-fired power plants. In 2021 and 2022, for instance, hydropower droughts and heatwaves raised power demand enough to cause severe blackouts, creating political pressure for a . In 2023, record-low hydropower generation led to record-high emissions.

China鈥檚 president Xi Jinping has said coal power would peak this year, but entrenched political support for the power source makes this a difficult prospect. 鈥淚f China suffers another round of those episodes, more coal-fired power plants should not be the answer,鈥� says Li. 鈥淚t鈥檚 just hard to phase out coal; China loves coal.鈥�