How do communication systems in spaceships work over long distances?

Spaceships communicate with Earth using radio waves transmitted through powerful antennae. The onboard communication system includes a high-gain antenna for focused, long-distance communication and a low-gain antenna for short-range or emergency contact. Signals are sent to Deep Space Network (DSN) ground stations, which receive and relay information. Data is often compressed and transmitted digitally to minimize loss. Because radio waves travel at the speed of light, messages can still take minutes or hours to reach Earth, depending on distance—like 20 minutes from Mars. Redundant systems ensure reliability, and modern spacecraft may use laser communication for faster and higher data capacity.