Mars' orbital speed varies throughout its orbit, but its average orbital speed is 24.077 km/s (14.968 mi/s).

Here's why it varies:

* Elliptical Orbit: Mars' orbit around the Sun is not a perfect circle, but an ellipse. This means that Mars is sometimes closer to the Sun (perihelion) and sometimes farther away (aphelion).

* Kepler's Laws: Kepler's laws of planetary motion state that a planet moves faster when it's closer to the Sun and slower when it's farther away.

So, Mars' speed is faster at perihelion and slower at aphelion. The average speed, however, gives us a good overall idea of how quickly it moves.