This article is from WeChat official account:Silicone (ID: guixingren123), author: Doutzen, edit: Vicky Xiao, the original title:” after the new crown healed, TCP / father of IP, to build the Internet space “, the title figure comes from:” interstellar “
Remember that in the sci-fi film “Interstellar”, astronaut Cooper saw the video of his daughter Murphy and his son Tom with his own eyes, and experienced the kind of longing and despair that spanned time and space, crying?
What is even more admirable is that this lens also accurately depicts how difficult and slow it is to transmit information across time and space under the irresistible laws of physics of the universe. The iron law of relativity cannot be bent. When Cooper received the video from the other side of the black hole, his children had already grown up, and he would never have lost an important time to grow with them.
One day in the sky, ten years on earth. The main creative team only used this very user-friendly lens to perfectly cut the theme of the movie “love through time and space”, which is impressive.
In the real world, humans have not yet invented a way to exchange information through black holes (even if there is a lack of test conditions). In fact, even the communication between the spacecraft and the ground and spacecraft still relies on radio frequency signals to a large extent. The complexity is not as high as expected, and it is notThere is no interconnection in the same system. Simply put, there is no Internet in space.
Then why not build an Internet for interstellar communications?
Vint Cerf, the co-inventor of the TCP/IP protocol, Turing Award winner, and known as one of the “Fathers of the Internet”, has been thinking about this issue since 1998.
He is 76 years old this year. He already has high blood pressure and coronary artery disease. He is a high-risk group. He contracted the new crown in March this year and he recovered.
Recently, Cerf accepted an interview with Quanta Magazine about the Interplanetary Internet Protocol DTN project he led.
Cerf is deeply concerned about the Internet today, believing that it is full of false information, virus software and cyber attacks. This is why he has transferred a large part of his energy to this brand new “Interstellar Internet” project-or more accurately, designing a set of the most critical underlying protocols for the future Interstellar Internet, just like TCP/IP Like the Internet we are familiar with.
“Compared with the Internet on Earth, the interstellar Internet is a very eye-catching new subject. It allows us to focus on pure scientific results.”
Why do you need interplanetary internet?
If you watched the live broadcast of SpaceX+NASA’s first manned space station flight by a private aerospace company a few months ago, you may remember that the various stages of the mission require many equipment inspections, which are completed through voice communication. After saying a word, it will take several seconds to receive a reply from the other parties.
This is only in Earth orbit. In the future, mankind will return to the moon, go to Mars to establish a base, and carry out more manned missions to farther space. Taking into account the relative positions of the earth, spacecraft, satellites, and other planets, as well as the astronomical distance, the call delay may become tens of seconds or even minutes.
Scientific exploration is always subject to various difficult conditions. In the past few decades, scientists have also had to adapt to this super-slow communication habit that cannot obtain immediate results. Take NASA’s Valor Mars rover as an example. Because of the weather at the ground satellite station and the long distance and other factors, it takes dozens of minutes from issuing an order to receiving feedback. Not to mention the data bandwidth of the rover is only 28Kbps,It overheats as soon as the antenna is turned on.
The feeling is that people who complain because Zoom can’t connect, it’s hard to imagine…
Mosaic photos of the Martian surface returned by the rover
People on earth who are used to the Internet with no delay, what will happen if they go to heaven in the future? Therefore, there must be interstellar Internet.
In 1998, Adrian Hooke, a veteran member of NASA’s Apollo program and a space communications expert, convened eight other people, including Cerf, to discuss a large set of topics: What is needed for future space exploration? Can you start doing it now?
One of the important issues is to improve the efficiency of space communications. Hooke’s group thought, can we combine the technology and logic of the Internet on Earth to improve space communications?
You can understand it like this: The space communication system at that time was largely fragmented and exclusive. For example, country A has issued a satellite that is responsible for a certain task, and another aerospace mission of country B temporarily needs relay communication, and the satellite of country A is in the middle, and the communication between the two systems will be found The methods are not compatible and cannot work together.
Half a century ago, the few networks on the planet did the same. Cerf is known as one of the fathers of the Internet. It is precisely because of TCP/IP as the underlying protocol that the subsequent global Internet has been achieved. In space, humans also need an underlying protocol that plays a similar role to TCP/IP, which will be the cornerstone of the interstellar Internet.
Hooke led the later Interstellar Internet low-level protocol project, and Cerf became an important technical expert of the team and has been making contributions. This business has been held todayContinued for more than 20 years.
(Actually, the status of the two in their respective industries is quite similar. Hooke has led and participated in the development of many space communication technology protocols and International standards, and also founded the International Space Agency Cooperation Organization CCSDS, which is committed to promoting the cooperation of official space organizations of various countries, including the shared communication protocol for spacecraft of various countries. Hooke passed away in 2012, and Cerf is still continuing the research of old friends.)
In the course of years of discussion and research and development, the team has summarized the following three current challenges in space communication, which are the reasons for the need for interstellar Internet:
(1) Physical limitations: Planets have different rotations and revolutions, and the range of distances varies greatly, resulting in long interplanetary communication, short windows, and unstable transmission. According to estimates, the communication time from Earth to Mars is at least a few minutes, and to Pluto it takes several hours. If you encounter an eruption of the sun, you miss the best time, and you don’t know when the next window opens.
(2) Small transmission volume: Subject to hardware design factors such as satellite quality, power consumption, cost, etc., the data load of traditional space communication is very small at present, and the data bandwidth is asymmetric , It can even reach 1:1000 up and down.
(3) Fixed infrastructure does not exist: Because of the first, the space communication from planet A to planet B, the routing nodes in the network change at any time, so there is no fixed infrastructure The relay network can connect two planets anytime and anywhere.
For example, an American device on the earth wants to connect to an Australian network, and there may be countless possible relay routes in the middle.(as shown below). In space, the establishment of communication between two devices requires advance planning and arrangement based on planetary movements and various conditions.
So, what exactly is the interstellar Internet proposed by Cerf’s team?
DTN: Interference/Delay Tolerant Network
In 2003, Hooke, Cerf and others jointly published a paper “Delay Tolerance Network: An Implementation of Interstellar Internet”, which formally proposed DTN (delay-tolerant networking) as a protocol standard for interplanetary Internet.
In essence, the DTN protocol uses a logic similar to that of the Internet: the data packet is used as the basic transmission unit, and the communication method of packet switching is adopted.(packet switching, That is, the data is divided into several segments during transmission, and each segment is a data packet); there are multiple routing nodes in the entire network structure.
The difference is that in the earth’s Internet, routing nodes are only responsible for forwarding, not for storing information. If the entire path is broken at a certain point, or network congestion is encountered, the routing node will discard the data packet. ——There is also the phenomenon of “packet loss” we often call.
In order to solve the three challenges of space communication mentioned earlier, the design of DTN requires that each router also have the ability to store data. For example, to send data from Earth to Jupiter, a router on Mars is needed in the middle. However, considering the rotation of the planet, or the relative position of fire-earth at that time is not appropriate, the data cannot be sent. The design of DTN requires that Mars routing should not be discarded, but the data packet should be stored and sent at the right time.
The figure below is a schematic diagram of the network structure of DTN in the paper. It can be seen that each routing node is not a simple point, but a circle representing a planet. Considering the different conditions of rotation and movement in space, and The communication path and bandwidth between another planet will change.
Ideally, if you are on enough planets (including on the ground and on orbit)There are enough routing nodes to say that a connection can be established between any two planets at any time. At least the space communication window will become longer and longer, and the communication will become more frequent.
What few people know is that the DTN concept proposed by Cerf et al. was put into use 15 years ago!
In order to solve the aforementioned rover data transmission problem, NASA JPL engineers remotely rewrote the communication protocol between the rover and the satellites launched into Mars orbit through a method similar to “OTA firmware upgrade”.
As a result, the Mars rover plus satellites, plus three ground satellite stations in Australia, Spain, and the United States, has become a mini version of the DTN-style interplanetary Internet.
Cerf’s team also conducted a test on the International Space Station, allowing the astronauts of the space station to successfully remotely control a robot in Germany through a communication method using DTN as the underlying protocol.
This test is of great significance for future human exploration of Mars and other extraterrestrial planets. After all, the delay for scientists to remotely control the Mars rover on Earth is 20 minutes. It is very possible that an operation will be sent and the car will be found after tens of minutes have passed. Under the cliff, billions of dollars of investment have been squandered… In the future, when an astronaut goes to Mars, you do not need to log in, and you can directly control the landing rover on Mars orbit.
In addition, when NASA’s Deep Impact probe was performing its mission to detect Comet Hartley II, it also carried the DTN communication protocol on board, helping the Cerf team expand the scope of the protocol.
In 2013, Deep Impact sent back photos of Comet Hartley II taken from about 700 kilometers away. This was also taken since the first discovery of Hartley II through an astronomical telescope in 1986. The clearest picture of :
Pictures are processed and enhanced
In 2018, Cerf and Google colleague Brian Barritt(Cerf also has the identity of Google Vice President and Chief Internet Evangelist) Co-published a new paper introducing the Loon SDN they designed-a software-defined network and cloud service for managing DTN network equipment.
You may be familiar with the name of Loon SDN, because its underlying technology comes from the original Google X Lab (Google renamed X Moon Landing after reorganization Laboratory)’s balloon Internet project Project Loon. Loon SDN can configure the wireless network structure on demand according to the situation, and transmit data packets between routing nodes in the earth’s atmosphere and space.
You can think of it as a cloud computing platform like AWS or Aliyun in space, allowing you to manage space communications more easily like managing a server thousands of miles away. In the era of software as a service, NASA’s next-generation space communication architecture design is also approaching in this direction.
Trying new technologies will always meet challenges, but Cerf is very confident in DTN. He believes that this agreement has been tested enough, and is also working to convince more space agencies and commercial space companies to integrate DTN into their systems.
He often hears things like “This is too risky!” “Prove me that this thing works!” Only by convincing these people to allow more spacecraft equipped with DTN-no matter which country, company, or mission they are from-to fly into the sky, can a real interstellar Internet be truly established.
Always WestThe three-piece Cerf gives the impression of a “technical gentleman”. In fact, he also has a famous T-shirt with a pun written on it, “I P on Everything”……
Because of the TCP/IP protocol co-created by Cerf, every Internet-connected device on the planet has an address.
If the ideal of DTN can be realized, then Cerf will have a new reputation: IP on everything, even in space……
This article is from WeChat official account:Silicone (ID: guixingren123), author: Doutzen, edit: Vicky Xiao