How do astronauts communicate with mission control from space?

Astronauts use radio waves and satellites to talk with mission control on Earth. Their voices travel through communication systems on the International Space Station, which sends signals to satellites orbiting Earth. These satellites pass the signals to ground stations, allowing astronauts to speak with NASA and other space agencies in real time. Video calls and data messages are also used for more complex communication. Because signals travel at the speed of light, there is almost no delay in low Earth orbit. However, for missions farther away, like to Mars, there can be a delay of several minutes.