Question

Mechanical (sound) waves to Earth from satellites. How is this possible? aves are unable to travel through a vacuum, such as through space, but radio waves are transmitted

Answer 1

Sound waves are not able to travel in a vacuum, sound requires a medium such as air or a solid for example.  Satellites are indeed in space, but radio waves are not sound waves they are a form of light.  Light can travel in a vacuum so the messages that satellites beam back to Earth are light waves not sound waves, that is why it is possible.