Question

Why is more fuel required for a spacecraft to travel from the Earth to the Moon than to return from the Moon to the Earth?

Short answer

The net gravitational pull helps the spacecraft in the journey from Moon to the Earth, so the requirement of fuel is less.

Step-by-step solution

Step 1. Understanding the surface gravity

The surface gravity of the Earth is much stronger as correlated to the Moon due to the huge variation in the mass of both of them.

Step 2. Evaluating the amount of fuel required for a spacecraft to travel from the Earth to the Moon than from the Moon to the Earth

When the spacecraft is traveling from Earth to the Moon, the amount of fuel required is more because the point at which the total gravitational pull on the spacecraft is zero is nearer to the Moon. This point is approximately situated at 90 percent of the path from the Earth to the Moon. Hence, the spacecraft consumes more fuel.

On the other hand, the returning of spacecraft from the Moon to the Earth requires less fuel because the point of total gravitational pull is closer. As the spaceship reaches this point, the gravitational pull helps it in the direction of motion.