Cellular networks are all the rage these days. A lot of people believe that mobile technologies will eventually replace desktops/laptops entirely. Regardless, they only work with terrestrial communications networks here on Earth. What if a similar network could be built beyond our planet? Considering that all electromagnetic radiation travels at the speed of light, the problem posed by interstellar communication is a pretty big one but may be the best shot we have at communicating with intelligent alien lifeforms (if they do in fact exist out there).
Messaging to Extra-Terrestrial Intelligence (METI) is the process by which astronomers attempt to purposefully communicate with alien life forms. All forms of electromagnetic radiation emitted from Earth, including radio waves from cellular phones, are moving in a shell at a constant rate away from our planet. That being said, this data isn’t particularly useful. It’s going to take a long time for it to reach a destination. If extraterrestrials were listening to any messages previously transmitted from Earth, it would probably be well over 100 years old.
There are plenty of other things that interfere with METI systems. Scattering, the Doppler effect, noise, signal attenuation and dispersion are all major issues. Signal attenuation is perhaps the most difficult to overcome since such great distances are involved. One might propose, then, that a system of interstellar repeaters would be an excellent way to conquer the ether of outer space.
Translator towers are often used to fill in the holes of FM broadcaster coverage maps. Likewise, cell towers overlap one another to provide a seamless web of communication. Many people even complain that humanity is quickly becoming far too connected for their own good. That being said, this sort of network model could just as easily be adapted to interstellar communication.
No one can build a system of interconnected satellites emitting METI messages overnight. It would probably take hundreds of years. That being said, many places in ancient times were settled in the same way. People built a settlement on an island or cliff and lived there for decades. Eventually, some adventurers from that town would move around and settle a new area. Likewise, that new dispersed settlement would produce another generation of adventures.
Some people have proposed constructing satellites in this manner to relay messages in the hope of making contact with an alien race. One could perhaps imagine making machines that use nanotechnology to continue expanding across a wide stretch of space. Of course, that comes with it’s own set of difficult questions. Either way, this is a difficult task (but not insurmountable). We’re actively listening for E.T. Perhaps it’s time for us to begin calling them as well.
Messerschmitt, D., & Morrison, I. (2012). Design of interstellar digital communication links: Some insights from communication engineering Acta Astronautica, 78, 80-89 DOI: 10.1016/j.actaastro.2011.10.005