Question

While passing between Earth and the Moon, a spacecraft is momentarily located on the line connecting the centers of the two bodies and is at a distance of d = 130 km from a radio antenna on the surface of Earth. The distance from the antenna to the moon is denoted by dm.

1. Recall that the speed of light is 3.0 × 108 m/s. How long, in seconds, does it take for a signal from the spacecraft to arrive at the antenna on Earth?

2. Scientists bounce a laser beam off the Moon and measure the two-way travel time to be 2.42 s. How far away is the Moon in meters?