The drawing of this mars rover, curiosity:
And this one is lunar rover:
As we can easily see, the engine is not planned here.
Let's take a look at the motion system of rover curiosity from wikipedia:
Mobility systems: Curiosity is equipped with six 50 cm (20 in) diameter wheels in a rocker-bogie suspension. The suspension system also served as landing gear for the vehicle, unlike its smaller predecessors.[49][50] Each wheel has cleats and is independently actuated and geared, providing for climbing in soft sand and scrambling over rocks. Each front and rear wheel can be independently steered, allowing the vehicle to turn in place as well as execute arcing turns.[33] Each wheel has a pattern that helps it maintain traction but also leaves patterned tracks in the sandy surface of Mars. That pattern is used by on-board cameras to estimate the distance traveled. The pattern itself is Morse code for "JPL" (·--- ·--· ·-··).[51] The rover is capable of climbing sand dunes with slopes up to 12.5°.[52] Based on the center of mass, the vehicle can withstand a tilt of at least 50° in any direction without overturning, but automatic sensors limit the rover from exceeding 30° tilts.[33] After six years of use, the wheels are visibly worn with punctures and tears.[53]
Curiosity can roll over obstacles approaching 65 cm (26 in) in height,[54] and it has a ground clearance of 60 cm (24 in).[55] Based on variables including power levels, terrain difficulty, slippage and visibility, the maximum terrain-traverse speed is estimated to be 200 m (660 ft) per day by automatic navigation.[54] The rover landed about 10 km (6.2 mi) from the base of Mount Sharp,[56] (officially named Aeolis Mons) and it is expected to traverse a minimum of 19 km (12 mi) during its primary two-year mission.[57] It can travel up to 90 m (300 ft) per hour but average speed is about 30 m (98 ft) per hour.[57] The vehicle is 'driven' by several operators led by Vandi Verma, group leader of Autonomous Systems, Mobility and Robotic Systems at JPL,[58][59] who also cowrote the PLEXIL language used to operate the rover.[60][61][62] Source: https://en.wikipedia.org/wiki/Curiosity_(rover)
As we see in the descriptions and drawings here, there is no reference to the engine.
This is a simple car with an electricity motor:
As we can see, normally electric vehicles have engines. Because, as we know, an engine is required to convert potential energy into motion energy.
While preparing these rovers, Nasa did not need the engine, electrical energy magically transformed into motion energy on the wheels. High magic technology. Or, Which of you forgot to put an engine in the car? No panic! There are magicians around!
