Interplanetary Internet

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A simplified physical arrangement of the Interplanetary Internet. Earth will act as the essential link in the network.

The Interplanetary Internet is a network of independent nodes in outer space that will act as the communication infrastructure between planets in our galaxy. It is the next step in the natural evolution of the Internet. As mankind continues to make extraordinary accomplishments in outer space exploration, the communications system which currently resides is becoming less applicable.

Since the distances between planets such as Earth and Mars are of such great magnitude, their needs to be a more efficient way of sending data back and forth without interruption. With this network infrastructure in place, the current communication problems that plague outer space missions will be avoided. This would in turn allow mission designers to create smaller aircraft's since payloads would be used less for communications equipment.

Contents

Background

The idea of the Interplanetary Internet was first created by Vint Cerf when envisioning the future direction of the Internet. His vision was a network of network's linked together by gateway's and run through the use of the Internet Protocol (IP) suite [3]. The network would form a backbone connecting a series of hubs on or around planets, ships, and at other points in space. These hubs would provide high-capacity, high-availability Internet traffic over distances that could stretch up to hundreds of millions of kilometers [6]. The Interplanetary Internet will be used for many different types of applications. Among them will be reliable communication between earth and other planets in our solar system.

The Interplanetary Internet will consist of three types of networks, working in conjunction. These are the backbone, planetary, and external network. The backbone will provide the common infrastructure for communication between earth, planets, satellites, and relay stations. The external network will consist of clusters of satellites flying between planets and other nodes, acting as a medium to forward packets. The planetary network is used to connect satellites orbiting a planet to its ground network [3].

Deep space exploration, until now, has been relying on sending a radio signal to a node when it came into range [1]. Software was being developed for one mission at a time, which decreased production time and the risk of errors. Placing a network in the sky, with each device acting as a node opens up the flexibility to provide readily accessible information quickly. With a network of remote nodes linked together, scientists and engineers could simply access information related to space missions as if checking email.

Applications

The Interplanetary Internet would serve as the primary data link between any residual points in outer space. An immediate application would be reliable data transfer between a Mars rover and Earth. The graphic to the right shows the steps of communication from one end point of the network to the next. There are many steps to consider when transmitting information across the galaxy. Many different networks are used to communicate the data efficiently.

Consider a scientist who is responsible for upgrading the software of a robotic device located on the surface of mars. The software would first be transmitted from the scientist's workstation to an antenna complex in the sky. Then the software module would travel through the galaxy to a system of relay satellites orbiting mars. This information would then be signaled down to the ground network and the software could be successfully uploaded into the robotic device [2]. Applications such as this are among the many that will become possible once the Interplanetary Internet is finished.

Challenges

Networking together the galaxy is no simple feat. The development and maintenance of the Interplanetary Internet faces many unique challenges that need to be over come. An engineering application of this magnitude has never been constructed, and requires expertise from many disciplines. The Interplanetary Internet is currently in its infant stages, and many of the challenges head have not even been thought of. The challenges that are currently known fall into three main categories.

Security Threats

One of the bigger challenges facing the Interplanetary Internet is security. For a network that could potentially be used as a life line between astronauts in space, and the Earth, it is extremely important to make sure there is no corruption of the system. Developers have been looking into a protocol which will be impenetrable by hackers [6]. One of the options to control access, recently being discussed is a variation of the Transport Layer Security (TLS) protocol. The TLS protocol allows client/server applications to communicate across a network in a way designed to prevent eavesdropping, tampering, and message forgery. TLS provides endpoint authentication and communications confidentiality over the Internet using cryptography. [1]

Technical Challenges

The technical challenges involved with the Interplanetary Internet are similar to those of any space oriented mission. Each of the nodes in the Internet will be potentially millions of kilometers from earth. Any damage to equipment will be expensive and timely to fix. This means that the transmission equipment used will have to be designed to be more robust than ever before. This problem is also being looked into by ensuring that multiple disabled nodes in the network does not discontinue the transmission of packets across the network [8].

Physical Challenges

Communication on Earth seems instantaneous compared to that of communicating to Mars because of the great difference in distances

There are certain unavoidable physical limitations when dealing with the Interplanetary Internet. Since message receiving from a rover on Mars, carrying astronauts, is of high importance, it is crucial to transfer all bits of a message. With the extreme distances from one relay station to another, 100% data delivery may be difficult to achieve. The distances involved are in the range of hundreds of millions of kilometers. At these distances, the time interval for a message leaving Earth to arrive at Mars will range anywhere from 5 to 10 minutes. This sort of lag is something the traditional internet is not accustomed to.

When a user makes a request on the Internet, the server responds by performing the request. This is a process that appears to happen instantly. This type of immediacy will dissolve as soon as the Internet expands into space. The Interplanetary Internet will run on a new process that uses a store and forward methodology in order to achieve more reliable rate of communication [4]. This process will be based on an entirely new set of rules called the Parcel Transfer Protocol (PTP).

Parcel Transfer Protocol

One of the major problems faced by the network of communication in outer space today, is the fragile connection strength between points. In order for Earth to relay a message to Mars, there must be a direct line of sight [2]. Any object between the receiver and signal transmitter will obstruct the communication. The Parcel Transfer Protocol will avoid this problem by using the store and forward method for packet transmission. The protocol would process an information request sent to a gateway and forward it to a final destination. The gateway would then check, process and forward information back down the path it came [6].

Disruption Tolerant Networking

Array of satellites used in Deep Space Communication

Disruption Tolerant Networking (DTN) sends information in a way that is unlike that of the traditional Internet's TCP/IP method. Through the direction of Vint Cerf, DTN does not assume an end to end connection, which is the case with the TCP/IP suite [7]. As noted earlier, many problems arise when a spacecraft is not in direct line with the end point receiver. For example, when a spacecraft is behind a planet, it cannot communicate with earth anymore, since the line of sight has been destroyed [8]. Disruption of transmission may occur because of the limits of wireless radio range, sparsity of mobile nodes, energy resources, attack, and noise [7]. The main component of any network is the ability to route packets to its correct destination. Many of the existing protocols fail with Disruption Tolerant Networks because they first try to establish a route, and then forward the packets. With the extreme environment, and instantaneous end points, selecting a route first is next to impossible. Disruption Tolerant Networking first used a method where multiple transmissions of the same message were sent, increasing the probability that one would reach its destination. Disruption Tolerant Networking is the basic idea associated with the far more advanced idea of the Interplanetary Internet.

See also

References

  1. IEEE Spectrum : Joab jackson, 2006. <http://www.spectrum.ieee.org/aug05/1700>
  2. How Interplanetary Internet Will Work : Kevin Bonsor, 2009.<http://computer.howstuffworks.com/interplanetary-internet.htm>
  3. Interplanetary Routing : Min Sheng, Ge Xu, Xia Fang, 2006. <http:://www.china-cic.org.cn/english/digital%20library/200612/9.pdf>
  4. On the Edge : Rich Gray, 2003. <http://www.space.com/businesstechnology/technology/ontheedge_0305.html>
  5. Interplanetary Internet : Wikipedia, 2009. <http://en.wikipedia.org/wiki/Interplanetary_Internet>
  6. Focus On : Interplanetary Internet : Mark Boucher, 1999-2009. <http://www.spaceref.com/focuson/ipn/>
  7. Delay-Tolerant Networking : Wikipedia, 2009. <http://en.wikipedia.org/wiki/Delay-tolerant_networking>
  8. IPN Technical Info : IPN SIG, 2008. <http://www.ipnsig.org/techinfo.htm>

External links

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--ziebac 18:36, 12 April 2009 (EDT)

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