嫦娥四号登上月球远端，开创世界航天新纪元

2019年1月3日上午10点26分，嫦娥四号月球探测器完成了人类史航天史上的一项壮举——成功软着陆在月球背面的南极-艾特肯盆地冯卡门撞击坑，并通过“鹊桥”中继星传回了世界第一张近距离拍摄的月背影像图，揭开了古老月背的神秘面纱，令世界瞩目。

外媒如是报道: 

中国月球探测器嫦娥四号正在飞往月球南极的环形深坑艾特肯盆地，如图中蓝色部分区域，据NASA美国太空总署称，从艾特肯盆地底部到最高峰的距离是珠穆朗玛峰高度的两倍。

2019年新年伊始，中国民用航天项目计划用一个六轮探测器在月球远地端登陆，而月球的那一面从未呈现在地球面前。

中方还没对外公布具体的着陆日期，虽然着陆地点已经公开。嫦娥四号探测器登陆目标指向月球南极一个巨大环形深坑，艾肯盆地。

虽然嫦娥四号的主要任务是科研目的，它仍然肩负相当一部分把中国宇航员送到月球表面的准备工作。

美国布朗大学的空间科学家吉姆海德表示，“美国足足完成了 21个机器人登月任务后才实现让阿姆斯特朗站上月球表面的壮举。"

海德补充：“之前的机器人登月项目为后来的宇航服以及月球探测器等的设计提供了各种各样的数据和背景，一步步地推动着人类探索世界的步伐”

而印第安纳州西拉斐特普渡大学的行星科学家 BrionyHorgan 表示，”这是人类第一次有机会能够更了解月球的另一端，真的令人振奋！”

研究科学家知道月球的远地面和近地面非常不一样，Horgan说：“远地面实际上非常原始-它的外壳非常远古，成形在很早很早之前的太阳系时期，布满40亿年前的岩石，我们真的很兴奋期待他们近看起来是怎么样的。“

那，为什么所有记载的登月都发生在近地端呢？主要是因为近地端比较容易通讯，Horgan解释说：“我们可以看到近地端，并且我们可以通过整个近地端面获得直接的无线通讯”

Horgan表示中国通过增加第三个组件解决了通讯问题。第一个组件是登陆车；登陆车携带着第二组件，一个可移动的探测车。第三组件是一个围绕月球远地端的卫星，作为地球和月球远地端的通讯中继。

这样，美国的登月任务是不是也可以很方便的使用这个中继卫星呢？目前看起来这是不可能的。美国法律命令禁止美国宇航局NASA和中国航天部门之间的合作，同时也有相关规则禁止美国向中国输出宇航相关技术。

不过布朗大学的Jim Head说即使有限制，两国航天科学家之间的交流是不可避免的。他认为这是好事。“当美国和其他国家能够通力合作取得最大化的科学产出，为什么我们要向月球同一个地方派出不同的飞船来做同一样的事呢？”

虽然中方不像NASA那样对民用太空计划非常公开，Head称其实也并没有那么完全封闭。“如果你找对了人，他们也并非完全不愿意沟通。虽然有很多保密方面的考虑，除此之外中方也非常愿意分享他们在民用太空计划方面的构想。“

美国在登月方面也有自己的野心。川普政府要求美国航天局集中精力在人类登月计划上，只不过非常有可能的是，当美国人到达月亮的时候，发现中国宇航员大哥已经在那里良久了。

以下为NPR原文：

The Chinese lunar lander Chang'e 4 is headed to Aitken Basin, a large impact crater near the moon's south pole, pictured here in blue. The distance from the depths of Aitken Basin to the tops of the highest surrounding peaks is nearly twice the height of Mount Everest, according to NASA.

Sometime early in 2019, the Chinese civilian space program plans to land a six-wheeled rover on the moon's far side — the side we never see from Earth.

The Chinese haven't released the exact date the landing is to occur, but they have announced the location. The probe, known as Chang'e 4, is targeted for Aitkin Basin, a giant impact crater near the Moon's south pole.

In addition to a variety of cameras, the rover carries ground-penetrating radar that can peer beneath the lunar surface.

Although Chang'e 4's mission is largely scientific, it is also a key bit of preparation for sending Chinese astronauts to the lunar surface.

"Before Neil Armstrong set foot upon the moon, the United States sent 21 robotic missions to the moon to prepare the way," notes Jim Head, a planetary scientist with Brown University.

"The robotic program is providing all the kinds of background that you would need for building space suits and things like that — like lunar rovers," Head says. "So they're building toward human exploration, for sure."

But beyond that, simply getting a chance, for the first time, to get a better sense of the moon's far side is exciting, says Briony Horgan, a planetary scientist at Purdue University.

Already, researchers know that the far and near sides are very different, she says.

"The far side is actually much more primitive — it contains really ancient crust that dates back to the very, very early solar system," Horgan says.

"There are rocks all over the far side that are over 4 billion years old," she adds. "We're really excited to see what those look like, up close."

So, why have all landing probes to date traveled only to the near side?

"Mostly because it's a lot easier to communicate with," Horgan explains. "We can actually see the near side, and so we get direct radio communication with the entire near side of the moon."

Horgan says the Chinese have solved the communication problem by adding a third component to their mission. The first component is a lander. The lander carries the second component, a mobile rover.

"The third component is a satellite that's going to stay in orbit above the far side of the moon, and act as a relay between the Earth and the far side of the moon," she says.

Though it might be handy if U.S. lunar missions could also use the relay satellite, that's not likely to happen. Official collaboration between NASA and the Chinese space program is essentially prohibited by U.S. law. There also are restrictions on exporting space technology from the U.S. to China.

But Brown University's Jim Head says even with the restrictions, there is communication among scientists from both countries. He argues that's a good thing.

"Why would we send a spacecraft to the same location to do exactly the same thing, when we can optimize the amount of scientific return for the United States and for other countries by collaborating as best we can?" Head asks.

And while China may not be as forthcoming as NASA about what their civilian space program is up to, Head says they're not completely opaque, either.

"If you talk to the right people, they're not holding things back," he says. "There are security issues there from their point of view as well as ours. But, nonetheless, they've been very forthcoming with their civilian space program."

The United States has its own lunar ambitions. The Trump administration has asked NASA to focus on returning humans to the moon. It's just possible there will already be Chinese astronauts there when they arrive.