Why is more fuel required for spacecraft to travel from the earth to the moon than to return from the moon to the earth?

More fuel is required for a spacecraft to travel from earth to the moon because gravity is against the spacecraft as it flies upwards away from earth. when the spacecraft is returning to earth from the moon gravity assists the spacecraft by dragging it downwards which causes the spacecraft to require less fuel because gravity is doing the work. i hope this .

Alinear relationship would look like a straight line on the graph. it could have a positive negative or 0 slope. so it could be a line potentially going in any direction but it must be perfectly straight.