Working on science fiction

Laser Communications Relay Demonstration (LCRD), artist’s illustration. Credit: NASA

NASA has released a video clip describing its plan to create a laser based communications system for space communication.

The system will be based on photonics chips using photons rather than electrons. Today space communications is based on radio signals (which involves electrons) and given the distances involved and the spreading of a radio signal the effective power that can reach the space craft (and the Earth from the space craft) is so minuscule that the data transmission is pretty slow (the Shannon limits applies to space communications as well...).

Yet, the need to transfer many more data is growing, as space crafts are equipped with more and more sensors. Radio communications is no longer an option.

Lasers can be much more effective but aiming a laser to a craft millions, billions miles away to an antenna is no easy task. The laser beam is good since it basically keeps its "size" and hence its power, but hitting the bull's eye become essential. 

In a radio communication you also try to beam the electromagnetic waves in the right direction but missing by a few degrees leads to lower power signal reception. With laser missing by a millionth of a degree means no communication at all.

Watching laser communications from the Enterprise (and the fake coloured laser beams) seems pretty straightforward. That is science fiction. Making it happen is science and it just seemed impossible. 
Now NASA has set a roadmap to make it happen with first tests already successful over some hundred thousands km (to reach the Moon). In 2018 they will start testing space communications over million of miles and by 2020 they plan to shift from radio comm to photons comm for all space mission. 

Interestingly, this is likely to have significant fall out for communications on planet Earth.

Author - Roberto Saracco

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