Landing on Mars is not an easy task. When the Earth and Mars are closest, there is also a distance of 56 million kilometers, which is 140 times the distance between the Earth and the moon. It is currently impossible to break through this distance with the power of a rocket. 
the probe needs to be thrown to Mars with the help of the revolution of the earth. However, it needs the right timing, which is the launch window. When the Mars rover reaches the aphelion, which is tangent to the orbit of Mars, and Mars also travels just there, the rover can rendezvous with Mars. Launching a Mars rover during this time window is not only the most energy-efficient, but the rover's payload will also increase accordingly. This particular timing and location only occurs every 26 months.
Emphasize the technical difficulties of the probe landing on Mars