Question

Astronauts use ________ to communicate with each other in space.

Answer 1

1. In a vacuum, there is no medium is present. So sound waves can not travel. They use radio waves and need some devices to communicate in a vacuum.
2. Radio waves are electromagnetic wave types best known for their uses in communication technologies, such as radio, television, and mobile phones.
3. These devices receive radio waves and convert them into mechanical vibrations in the speaker to create sound waves.

Hence, astronauts use radio waves to communicate with each other in space.