Why is more fuel required for spacecraft to travel from the earth to the moon than to return from the moon to the earth?
I will be happy to critique your thinking on this.
Wouldn't it be because you are going against gravity and when it comes back to earth it's going with gravity
To understand why more fuel is required for spacecraft to travel from Earth to the Moon than to return from the Moon to Earth, we need to consider the principles of orbital mechanics and the concept of delta-v (change in velocity).
When a spacecraft launches from Earth, it needs to overcome the gravitational pull of our planet and escape Earth's gravity well. This requires a significant amount of energy, known as the delta-v expenditure. The spacecraft must accelerate to a speed of approximately 40,270 km/h (25,020 mph) to break free from Earth's gravity and enter into lunar trajectory.
On the other hand, when the spacecraft is returning from the Moon to Earth, it takes advantage of the Moon's significantly lower gravitational pull. The Moon has only about 1/6th the gravitational force of Earth. This reduced gravity means that the spacecraft doesn't need as much fuel to launch from the Moon's surface and attain lunar orbit.
Additionally, there is another crucial factor called the Oberth effect. The Oberth effect states that the efficiency of using a given amount of fuel increases with higher speeds. When a spacecraft is returning to Earth, it can utilize the Oberth effect by performing a technique called a "gravity assist" or "slingshot maneuver." By taking advantage of the Moon's gravity, the spacecraft can gain extra speed, thereby reducing the overall delta-v required to return to Earth.
In summary, more fuel is required for the spacecraft to travel from Earth to the Moon due to the need to overcome Earth's gravitational pull and achieve lunar trajectory. However, on the return journey, the lower lunar gravity and utilization of the Oberth effect allow the spacecraft to use less fuel to return to Earth.