Title. Also maybe more extreme, but how is the Mars Rover sending pictures to earth. I cannot grasp how this works over such a long distance.
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Energy cannot be destroyed and there is almost nothing in space that can absorb a radio signal. So a radiosignal can go on pretty much forever in space.
The main thing that makes a radiosignal weaker is that all that energy it had at the moment of transmission spreads out over a larger surface. If you send it omni-directionally (in every direction) that energy forms like a bubble of radio energy. Since radiowaves travel at the speed of light (or close to it) that “bubble” becomes bigger pretty fast so the radio energy gets really spread out (and weak).
There are two ways of making it better at reaching long distances.
The first way is that you can direct the radio energy in a single direction. So instead of forming a big balloon bubble of radio energy it’s more like a very narrow flashlight. The narrower you make the beam the more energy is concentrated at a single point, but concentrating radio energy is pretty tough and you could also miss your target if you don’t point it in the right direction. Long distance communication almost always use Directional antennas (high gain antennas) that send their signal in a narrow cone.
The second way is to build a giant radio-dish on the receiving end (google what a radio telescope looks like). That radar dish will gather up all of the radio energy that hits the dish and bounce it towards a single point. The bigger the radio-dish is the more energy is concentrated and a weaker signal can be detected. The radio-dishes that we use to listen to stuff like the Mars Rover or Voyager, and send back instructions, are pretty big compared to antennas we use to communicate on earth (compare the size of a radio telescope to the satellite dish people use to get Satellite TV. And Satellite TV signals aren’t very concentrated compared to the signal communication satellites at mars send out)
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