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科普知识 | 1吨月壤中约含170克水!嫦娥五号矿物表层带来新发现_嫦娥五号月壤中发现存在高含量水_月球_我的网站

A | Beginning next week, people wanting to enter certain public facilities in China will need to show proof of COVID-19 vaccination or of having a medical reason for not getting the shot, Li Ang, deputy director of the Beijing Municipal Health Commission, told reporters on Wednesday.,The list includes museums, theaters, stadiums, gyms, and other entertainment venues; in addition, elderly people will also have to show proof of vaccination to enter community facilities such as game rooms. Restaurants and public transportation are exempt from the new requirement.,The new mandate is in addition to a standing requirement for residents of the Chinese capital city to get tested every three days and to need a negative test to enter public venues.,A year ago, when the Delta variant of COVID-19 caused the worst outbreak in China since the one that started the pandemic, and Beijing responded by ushering in the “Zero Covid” policy, the National Health Commission urged provincial authorities to keep the vaccination program “informed, consented and voluntary” and not to introduce mandates for public access, as many Western states had done.,However, that was before China succeeded at vaccinating 87% of its 1.4 billion-strong population, including 97% of Chinese adults, and before the Omicron variant caused the worst and most persistent outbreaks for China until now in the pandemic.,The change also comes as the NHC relaxes travel quarantine requirements for the first time since the start of the pandemic in early 2020, but also as Beijing health authorities indicated they were planning for “Zero Covid” to last another five years.,The NHC reported 427 new cases on the Chinese mainland on Wednesday, most of them concentrated in the eastern provinces of Anhui and Jiangsu, and no new deaths. The news brings the total detected cases on the mainland since the start of the pandemic to 226,176, while total deaths remained at 5,226. The situation has been less rosy in Hong Kong, a special administrative region with greater autonomy, and in Taiwan, where an autonomous government with foreign backing rules in defiance of Chinese claims of sovereignty.,Paradoxically, Chinese elders have a lower vaccination rate than younger generations. Last month, the Financial Times reported that Chinese cities had begun offering “vaccine insurance” to people over the age of 60, pledging to cover their medical costs related to any potential complications caused by vaccination. Some two-thirds of Chinese citizens over 60 are under-vaccinated, with 95 million not having gotten their booster shot as of June 5.,Ma Chaofeng, a health official in Shaanxi’s capital of Xi'an, told reporters on Tuesday that more than two dozen cases had been detected in the city and were identified as the BA 5.2 subvariant of Omicron. The city introduced new mass nucleic testing on Wednesday in an attempt to stay ahead of a larger outbreak, with most commercial and medical institutions remaining open as normal. Nonetheless, in the West, where essentially all pandemic mitigation measures have been discarded, the move was described as “Xi’an shuts back down.”,“The transmission chain is clear, the source is clear,” Pang Xinghuo, deputy director of the Beijing Centre for Disease Prevention and Control, told reporters on Wednesday about the imported cluster in Xi’an. “The outbreak is considered to be controllable overall, based on the existing epidemic development trend.”。

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C | ”张爱铖告诉记者,太阳风主要由氢和氦组成,它不断地吹向月球表面。月球没有大气,没有办法阻止太阳风粒子的轰击,所以太阳风的氢和氦就会被注入到月球表面的月壤矿物中,但是注入深度很有限,主要是在矿物的表面。“如果月壤因为微陨石撞击发生局部熔融形成玻璃,这些矿物表面的水就会被转移到玻璃中或者部分丢失。”月球上除了太阳风成因水,还有月球自身的水、小行星或彗星带来的水。“虽然月球在形成的时候有部分水可能残留下来,在月球漫长的演化历史中慢慢富集。”张爱铖介绍说,“比如月球玄武岩(月幔熔融形成的熔体喷发到月表的岩石)中一种叫磷灰石的矿物就可以含有达到几千ppm的氢氧根形式存在的结构水。”而富含水冰的小行星或者彗星当撞击月球表面时,虽然大量水在撞击时蒸发了,但仍有一些水深入月壤中存留下来。一吨月壤含水约170克,相比之下,地球上一吨沙漠中沙子的含水量可达十几公斤。

D | 月球上的水为何消失那么快?月壤中的水绝大多数是太阳风贡献的,而月岩中的水大多数是岩浆凝固前就有的。“陨石的撞击、太阳辐射都会导致月壤中水的丢失。”张爱铖认为,一方面,陨石撞击会带来短时间的高温,从而导致撞击坑及附近的一些月壤失去水。

E | 另一方面,虽然月球表面白天的温度不是特别高,但因为月表接近真空,太阳辐射的温度有可能会导致月壤矿物表面的水释放和迁移。

F | “避免太阳的辐射,可以帮助月球上的水不丢失。”月表矿物是重要的储水“仓库”,那月幔中会有水吗?“嫦娥五号玄武岩月幔源区,每克岩石的水含量不超过5微克。”嫦娥五号月球样品中的月海玄武岩,是月球最“年轻”玄武岩之一,年龄为20亿年,其晚期岩浆活动的源区并不富集放射性元素。“嫦娥五号着陆区异常活跃的火山活动既不能归因于源区富集放射性生热元素,也不是由于源区富含水,这对未来的科学研究和月球探测提出了新的目标。

G | ”在科幻电影《火星救援》中,宇航员在火星种起了土豆。月球上发现的水能否用来种菜?“种菜需要液态水,但是目前尚无确凿证据表明月球表面存在液态水。”张爱铖介绍道,目前月球上存在的实际上是矿物中的结构水,主要是以氢离子或者氢氧根形式存在,不易被植物吸收。“当然,从科学角度讲,月球矿物中发现的水是可以通过技术手段释放出来的,但是成本比较高。前人曾经依据遥感探测手段,提出月球两极阴影区会有水冰存在。

H | 如果能采集到这些水冰,用于种菜是有可能的。”来源:交汇点新闻编辑:李艳茹校对:韩博初审:薛腾霄终审:刘波相科普知识 | 航天员出舱作业为什么不会“飘走”?南航专家解析中国空间站航天员第五次出舱作业 关科普知识 | 黑洞真会发声吗? 链科普知识 | 生活中的辐射对人体有害吗? 接科普知识 | 一图读懂暗物质粒子探测卫星 大力建设科技强省勇当科技创新开路先锋微信公众号:JiangSu_ST点分享点收藏点点赞点在看返回搜狐,查看更多责任编辑:

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