Communications of the ACM

Communications of the ACM

Understanding Meteor Burst Communications Technologies

By B. Craig Cumberland, Joseph S. Valacich, Leonard M. Jessup
Communications of the ACM, January 2004, Vol. 47 No. 1, Pages 89-92
10.1145/962081.962085
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For years, humans have been searching for alternative methods of communicating across distances, including local telephone service, local Internet service, analog/digital cellular service, satellite communications, and wireless local area networks. Here, we describe a communications technology that while not new (it could be accurately described as reemergent), is now much more feasible given the incredible advances in technologies since it was initially developed in the late 1930s. Meteor burst communications technologies (MBC) represent an exciting new opportunity for investigation by both companies and research organizations to identify, develop, and utilize this amazing and essentially freely available communications resource.

Millions of meteors enter the earth's atmosphere, burning up on their fiery entry, 24 hours a day, 7 days a week, 365 days a year.¹ These meteors vary in size from pieces of space debris no bigger than a grain of sand or a kernel of rice to micro-meteors the size of a speck of dust [1]. Since the earliest civilizations, humans have watched in awe, where and when possible, this display of celestial fireworks. Now, people have learned to harness this power and use it to achieve their own objectives.

By utilizing the ionized trail of gases left from the entry and disintegration of the meteors, individual scientists and companies are able to create communication networks between different points by reflecting a signal up off the disintegrating meteor's trail of ionized gases and back down to a receiver station, located up to 1600km away [2].

As the earth orbits the sun, a great number of tiny meteors are swept up into the gravitational pull of the earth. The meteors are actually space debris, leftovers from the formation of the universe or remnants of a passing comet. As they enter the atmosphere, the meteors collide with an increasing number of atmospheric particles [1]. The kinetic energy from these collisions changes into heat, light, and ionization, described as "burning up." As the outer layers of the meteor burn up, they lose velocity vs. the central core and result in the "tail" of ionized particles that forms behind the meteor [3]. The meteors themselves usually end their existence as a stream of hot gases and charged electrons.

It is during the process of disintegration of these meteors and their residual ionized particle trails that the meteor trails are capable of reflecting radio waves, or reradiating (that is, wireless communications) between two or more communications points. Since these trails exist in a useful state 80–120km up in the atmosphere, they can permit communications over the horizon (curvature of the earth) at distances up to 1600km [2].

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Meteors for Communications

Although up to a billion meteors can enter the atmosphere in 24 hours, only a fraction have the proper speed, size, and trajectory (SST) or entry geometry, to be useful as a communications medium [7]. The SST plays a crucial role in the amount of the communicated signal received. The following factors are also critical to the maximum transmission rate possible to achieve during an exchange:

• The tail must form a direct tangent line that coincides with the location of the master and remote stations involved in the exchange [7].
• The maximum ionization of the particulate matter must occur around that point of tangency. This takes an electron density of about 10e+14 electrons per meter, requiring a meteor with a typical mass of 0.001 grams and a diameter of 1mm. Larger meteors are more useful, but rarer [7].

Figure. Master-to-remote communication (Meteor Communications Corp., Kent, WA) [5].

The communications channel's existence is somewhat random but still statistically dependable and determinable, usually occurring about every 10 seconds. In addition to the somewhat random availability of a good reflective trail, the time of existence of these trails is extremely limited. As the meteor enters the atmosphere, ionization begins. The optimal time of usefulness of the ionized trail is at a distance of between 120km and 80km while descending through the atmosphere. As the meteor descends, increasing numbers of particles are ionized and begin to disperse, and as the trail spreads out, this causes a multipath pattern, detracting from the communications capability of a given trail. Eventually the useful signal strength for that trail goes to zero. A good-quality meteor communications trail lasts for less than one second (the average is 0.3 seconds) [2].

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How Does It Work?

A typical MBC network is generally organized as follows: A large base station (master) with approximately 5,000 watts of radio power and a large antenna array is used in conjunction with any number of remote sites, each with a 100-watt radio and a directional antenna [1]. The master station transmits a continuous, coded signal (probe) in a certain direction and angle, at a predetermined power level. When a meteor appears with appropriate SST, it reflects the signal from the master station back down at the earth to the remote station. The remote station, which has been idle until it is "awakened" by the reception of the probe signal, decodes the signal, turns on its own transmitter, and sends a response signal back along the trajectory path to the master station.

Data can then be exchanged as long as the link (trail) is reliable enough for accurate reflection (but is subject to diffusion as mentioned previously). Since the duration of a meteor trail can be extremely short, data transfer between these sites consists of bursts of high-data-rate transmissions (thus the name, meteor burst communications) [6]. If the data that must be transmitted cannot be transmitted all in one burst, then multiple successive bursts can be utilized to move larger sets of information.

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What is the Opportunity?

An increasing number of companies and organizations are investigating and utilizing this technology in production (various governments, departments of defense, and commercial groups). It seems clear, as evidenced by the companies investigating it and the growing body of academic and industry-related literature concerning MBC, that this technology can provide a significant alternative communications paradigm to standard satellite and land-line communications.

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While MBC was not initially designed and developed with the intent of displacing satellite systems, current satellite communications customers should seriously consider whether the costs for satellite air time are warranted given the availability of MBC technologies.

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The disadvantages of satellite systems are significant. Commercial satellite time is extremely expensive and availability of channels is quite limited. Also, high-frequency and satellite communications are easy to disrupt and can be received over a large area; thus they are easily intercepted and are not well suited to military utilization. While MBC was not initially designed and developed with the intent of displacing satellite systems, current satellite communications customers should seriously consider whether the costs for satellite air time are warranted given the availability of MBC technologies.

Table 1. MBC characteristics [4].

Table 2 presents several examples of the potential uses of this technology and some of the ramifications of that use. In general, governments and for-profit organizations are investigating the development of applications that can utilize an MBC network for such things as backup messaging systems (email or paging), data acquisition and remote sensing networks, broadcasting services, and vehicle tracking systems. Over the past few years, several companies and applications have been created, while others are still under development and investigation.

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Governments and for-profit organizations are investigating the development of applications that can utilize an MBC network for such things as backup messaging systems (email or paging), data acquisition and remote sensing networks, broadcasting services, and vehicle tracking systems.

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Conclusion

Although meteor burst communications was originally developed during the 1930s–1940s, it is only recently, with the refinement of higher-quality communications equipment and computational resources and technologies exponentially greater than anything available at the time of its initial development, that we might begin to fully realize the potential of this reemergent communications capability. Imagine a network not controlled or owned by any government or company that can have an enormous range of applications to commercial, governmental, and educational environments around the world. MBC can provide a relatively low-cost, reliable communications system for data transmissions across large distances.

As with any technology, MBC has advantages, disadvantages, and limitations. Our challenge now is to determine the contexts in which MBC can be best utilized. Further, we need to determine how best this technology can be managed so that it is not misused. In any event, when next we see a shooting star on a clear night, we will be in awe not only of its natural beauty but also of its potential as a method for communication.

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The Digital Library is published by the Association for Computing Machinery. Copyright © 2004 ACM, Inc.

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