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Across the world's space agencies, there are dozens of spacecraft currently on missions beyond Earth.
世界各地有很多航天机构正在地球之外通过宇宙飞船执行任务。
But space is big. Really big.
但宇宙很大，非常大。
And the farther away the craft is, the weaker its signal is when we receive it.
宇宙飞船离得越远，我们收到的信号就越弱。
Also, any signal we want to send from Earth gets weaker, too.
而且我们从地球发出的信号也会越来越弱。
So in order to talk to these far-flung extensions of humanity, we have a special network of radio dishes.
所以，为了跟宇宙飞船保持对话，我们创建了射电抛物面天线的特殊网络。
It's called the Deep Space Network, or DSN for short.
这种网络名为深空网络(DSN)。
And it's not just a messenger. It does science, too!
深空网络不只起到信使的作用，还会做科学研究。
While it's operated out of NASA's Jet Propulsion Laboratory, the DSN's radio antennas are at three facilities around the globe, one in Australia, one in Spain, and one in California.
虽然深空网络是在美国宇航局外的喷气推进实验室运营的，但它的无线电天线在全球各地有三处部署，分别在：澳大利亚、西班牙、美国加州。
These bases are roughly the same distance apart, to make sure that any spacecraft can stay in constant communication, even as Earth rotates.
这三处部署彼此之间的距离差不多，这是为了确保所有宇宙飞船都能持续保持联络，不管地球如何自转公转。
At the beginning of 1958, the forerunner to the DSN was created.
1958年初，深空网络的先驱出现了。
JPL deployed portable radio tracking stations in California, Nigeria, and Singapore to help pilot Explorer 1, the first manmade American object to fly around the planet.
喷气推进实验室在加州、尼日利亚和新加坡部署了便携式无线电追踪站，目的是助力第一颗美国人造卫星探险者1号环行。
The actual DSN was established in December 1963, but its various radio antennas were built in later years, and upgraded over the decades.
深空网络首次创建是在1963年12月，但它的各种无线电天线是在过去几年间建造而成的，并在过去几十年间进行过升级。
During those decades, it helped steer the first satellite to enter another planet's orbit, land the first lander on an asteroid, and show the entire world Neil Armstrong's first steps on the Moon.
这些年里，无线电天线可以帮助这颗卫星进入另一颗行星的轨道、在某颗小行星上让着陆器着陆，还可以展现尼尔·阿姆斯特朗首次登陆月球的脚印。
You know, no big deal.
总之这些都是小菜一碟啦。
To talk to spacecraft, the DSN has three groups of different sized antennas.
要与宇宙飞船交互，深空网络设置了3组大小不同的天线。
The largest measure 70 meters across, and are how we communicate with the most distant objects, like Voyager 1, which, by some definitions, is past where the solar system ends.
最大的一组有70米长，这组也是我们与最遥远物体（比如旅行者1号）沟通的媒介，而最遥远的物体从某种角度看已经超过了太阳系的范围。
Why so big? Well, by the time Voyager's signal gets back to Earth, it's 20 billion times weaker than what's used to power a digital watch.
为什么会如此之大呢？因为等旅行者1号的信号返回地球时，其信号强度是数字显示式电子表的1/200亿了。
And because the signal is so weak, the dish can't have any deformations in it.
而由于信号如此之弱，射电抛物面天线内部已经没有变形存在了。
So that 3,850 square meter surface is shaped perfectly to within a single centimeter.
所以这3850平方米的表面形状就可以完美适配于1厘米之中了。
Each site also has at least one antenna that's 34 meters in diameter, and a single 26-meter antenna used to track Earth-orbiting spacecraft.
每一组还有至少1根直径达34米的天线，以及一根直径26米的天线，用来追踪环绕地球的宇宙飞船。
All these antennas are equipped with amplifiers to hear faint signals.
这些天线上都有放大器，可以接收到微弱的信号。
But that also means any background noise, including radio static emitted by basically every object in the universe, gets amplified, too.
但这也意味着环境里的杂音，比如宇宙里各种物体释放出的无线电静电也都会被放大。
So astronomers encode the signals in such a way that they can distinguish satellite signals from noise.
所以，天文学家对信号进行加密，让卫星信号与杂音区别开来。
There's also the trouble of the equipment itself producing noise in the form of infrared radiation, AKA heat.
此外，设备本身也会以红外线照射（也就是热量）的方式来产生杂音，引发问题
So the amplifiers are designed to work at really cool temperatures, within a few degrees above absolute zero, so the heat signal doesn't overwhelm the sensors.
所以，信号放大器被设计为可以在极低温下——只比绝对零度高几度——工作的款式，这样的话，热量的信号不会掩盖感应器了。
Another way the DSN can amplify communication is by using the multiple antennas to collect a signal from the same source.
深空网络增强交流信号的另一种方式是使用多重天线来从同一源头收集信号。
This is called arraying, and it works really well for radio waves because the wavelengths are so long.
这种方式叫做天线阵，对无线电波很奏效，因为波长很长。
So you don't have to worry as much about things like interference from the atmosphere.
所以不必过于担心来自大气层干扰等问题。
All together, this means the DSN is even capable of finding and tracking “lost” spacecraft, ones that aren't sending out a signal anymore, just by acting like a big radar gun.
综上所述，深空网络甚至可以发现并追踪“失踪的”宇宙飞船，所谓“失踪”，是指宇宙飞船不再发射信号，就像一支大型雷达枪一样。
In fact, it managed to track down India's Chandrayaan-1, which is orbiting the moon!
实际上，深空网络追踪到了印度月船1号的行踪，这可是围绕月球飞行的卫星！
But the DSN isn't just for tracking and talking to spacecraft, even though it's pretty dang good at it.
不过，深空网络不只可用于宇宙飞船的追踪和交互，虽然这是它的拿手绝活儿。
Every once in a while, it gets in on some science, too!
偶尔，深空网络也可以做科学研究哟！
A lot of times, it works with spacecraft.
很多时候，都是和宇宙飞船一起完成的。
For example, by detecting changes in the signals it receives, it can help determine the composition of whatever the spacecraft is orbiting.
比如，它可以通过检测其所收到信号中的变化情况来助力确定宇宙飞船所围绕飞行物体的组成。
Back during the Cassini mission, the DSN helped find the first evidence of a liquid water ocean underneath the surface of Enceladus.
想当年卡西尼号出征期间，深空网络就曾助力首次发现了土卫二地表以下液态海洋水存在的证据。
As Cassini flew past Enceladus, different regions had different gravitational pulls on the satellite, because they were made of different stuff.
卡西尼号飞过土卫二身边时，不同的区域受到了该卫星不同的引力作用，因为不同区域的组成材质不同。
That changed Cassini's velocity, which caused the frequency it transmitted to be shifted just a little bit.
这就改变了卡西尼号的速度，使其发送信号的频率发生了改变。
The DSN picked those changes up, and allowed astronomers to figure out that there had to be water underneath the surface.
深空网络识别出了这些变化，让天文学家得以判断出土卫二地表以下存在水源的情况。
And speaking of Cassini, the DSN was also used to study what Saturn's rings are made of.
此外，说道卡西尼号，深空网络还曾用于研究土星环的组成。
Back in 2005, Cassini conducted its first radio occultation observations.
2005年的时候，卡西尼号曾进行了第一次无线电掩星观测。
Basically, it sent a radio signal from behind the rings, to Earth.
这种观测就是从土星环后面发射无线电信号给地球。
The denser the ring, the weaker the signal the DSN received.
土星环密度越高，深空网络收到的信号就越弱。
And by using three different radio frequencies at the same time, which were each affected differently based on the rings' particle sizes, astronomers could get both density and composition profiles.
三种不同的无线电频率会不同程度地受到土星环粒度的影响，通过使用这样的无线电频率，天文学家得到了密度和组成材质。
But the DSN can work alone, too. It can directly image objects, like asteroids, by bouncing signals off them, a technique called radar astronomy.
深空网络也可以独立工作。它可以直接拍摄物体的图像，比如小行星，方式就是获取从物体身上弹射回的信号，这种技术也称雷达天文学。
And it's even been used to test predictions that come out of general relativity.
人们甚至还曾用深空网络来检验广义相对论的预测是否正确。
For instance, it sent radio signals to the Viking spacecraft while Mars and Earth were basically on opposite sides of the Sun.
例如，深空网络曾向海盗号宇宙飞船发射过无线电信号，当时，火星和地球都在太阳的相对面。
And that showed that light passing near a massive body takes longer to travel, which is gravitational time dilation!
结果显示，经过特大质量物体的光线需要更长时间才能穿过，这是因为引力时间膨胀的作用。
So here's to you, Deep Space Network.
所以关于深空网络，今天就讲到这里啦。
If it weren't for you, we'd know so much less about the solar system.
如果不是因为深空网络的存在，我们对太阳系的了解就不会有今天这样多。
Thanks for watching this episode of SciShow Space!
感谢收看本期的《太空科学秀》！
If you want to learn more about space history related to the DSN, check out our video about how the US launched Explorer 1 in the late 1950s.
如果您想了解与深空网络有关的更多宇宙历史内容，可以查看我们有关上世纪50年代末美国发射的探险者1号哦。
