While the Apollo astronauts were on the Moon, 3.844 x 10 8 m away, they communicated using radio - w aves, which travel at the speed of light. The Earth’s atmosphere, which is about 160 - km thick, does not appreciably affect the speed of the signal. About how long will the ground controller have to wait from the end of a question to the start of an answe r, given that an astronaut takes 1s to respond?