"Prograde" refers to the direction of an object's movement that is aligned with the rotation of a celestial body, such as a planet or moon. In the context of space travel, when a spacecraft moves prograde, it is traveling in the same direction as the body's rotation, which can help increase its speed and efficiency. In contrast, the term "retrograde" describes movement in the opposite direction. For example, when observing the motion of planets like Mars or Jupiter, their prograde motion can be seen as they orbit the Sun. Understanding prograde motion is essential for planning efficient space missions and satellite orbits.