This is the fourth of four articles to suggest solutions to the problems that would be caused on Earth from the loss of satellite services. I briefly describe the situation in a previous posting at Impending Space Junk Disaster. This article discusses the use of lesser known terrestrial communications systems to provide connectivity to replace that which is currently provided by space based platforms.
Telecommunications is the only service that can be backfilled upon loss of satellite services. Space based imaging, mapping, and other remote sensing (such as detecting lightning and forest fires) would be almost totally lost in the absence of satellites. Military intelligence would be relegated to methods from the 1960s, such as high altitude aircraft flyovers (with all the associated limitations and risks including being shot down). However, it would be possible to provide telecommunications services from solely terrestrially based equipment.
There are three additional types of systems that come to mind (beyond those discussed previously), and those are as follows:
- Meteor burst—using short lived ionized trails from meteors burning up in the atmosphere
- Tropospheric scatter—bouncing high power signals off of an area of the troposphere that can be “seen” by the same two terrestrial stations greater than direct wave distance from each other
- Free-space optical communications (FSO)—basically laser or light beams that are modulated with communications voice and data
Meteor burst communications has come a long way since it was first discovered in the early 20th Century.1 Part of the improvements today are from computer processing and better crafted antennas and radio equipment. The frequencies used are generally in the 30-50 MHz (lower VHF) range. Meteor burst systems utilize the higher altitude ion trails from meteors burning up in the ionosphere—which is different from the ionization caused by the sun’s rays in the upper atmosphere, although both of these phenomena affect the same atmospheric region. Even though ionized meteor trails typically last only fractions of a second, there are enough of them to potentially provide usable data throughput, especially when using a Feedback Adaptive Variable Rate (FAVR) system.2 Terrestrial distances covered by meteor burst systems can exceed several hundred kilometers. That’s not bad considering it’s riding fleetingly transient small ionized clouds.
Tropospheric scatter communications systems have been around about as long a meteor burst systems. While meteor burst systems send signals through the ionospheric region, tropospheric scatter systems send signals through (as the name implies) the troposphere, where we live and breathe.3 Although only a small fraction of the transmitted power arrives at the receiver (much more loss than straight square of the distance reduction), enough makes it through to provide a usable signal—in some cases with impressive data rates for such a marginal transmission medium.4 This is another system that you won’t be watching movies on, but it could help off load some of the traffic to let you watch movies on other higher bandwidth systems when the satellites are no longer functioning.
The third technology mentioned is basically a bright focused flashlight, modulated with the data it carries. The free-space optical communications (FSO) discussed here is different from laser beam communications aimed between tall buildings that are close to each other. Much of the discussion about laser communications pertains to use cases between satellites—those systems would be moot in a Kessler Syndrome disaster. However, FSO communications for terrestrial applications would be quite viable, and without the bandwidth limitations of meteor burst or troposcatter. It may be more feasible (and cheaper) to install a mesh network of chained FSO terminals than it would be to try to lay new fiber optic cable. The main problem with any light wave communications system would be with its significant attenuation in fog and other inclement weather—even there, techniques are being developed to manage that too.5 Having applications in space doesn’t preclude a technology from being also useful for terrestrial applications.
All of the technologies discussed here have had their greatest advocacy, development, and deployment in support of military, space, or maritime purposes. Although the impetus for initial development may have come from those areas, these systems would be serious candidates for augmentation of terrestrial communications in the absence of satellite services.
The point of this series of articles is that even though so much is dependent on satellite communications and space based services, losing satellites doesn’t have to be the end of life as we know it. And the fall would be cushioned if we prepared in advance—it would be prudent to do so.
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