How do spacecrafts transmit images back to Earth?
To expand a little on IndianaJohn’s answer, it’s pretty tough to get data from spacecraft that far from Earth. First of all, the spacecraft is operating with a limited amount of power. In the case of the Voyager missions, the power is provided by the heat produced from the radioactive decay of plutonium, and as the fuel gets used up and the generation system gets a little less efficient over time, the available power gets even lower. The strength of a radio signal is going to depend directly on the power it’s generated with, and of course, some of the spacecraft’s power is devoted to its other systems. Second, the spacecraft is sending a radio signal with a finite ability to focus it. That means the signal spreads out as it travels away from the spacecraft. The amount of the original signal that gets collected by a receiver on Earth is therefore pretty small. It’s kind of like a flashlight – if you hold a penny (your receiver) an inch away from a flashlight in a dark room, it’s going t
