Ingenuity disables its optical height detection system a short distance over ground because kicked up dust could interfere with it. It proceeds downwards until

Ingenuity disables its optical height detection system a short distance over ground because kicked up dust could interfere with it. It proceeds downwards until it makes contact with ground. To reliably detect the acceleration of that, they have to "slam it" into ground at a speed of approximately 1 m/s. Edit: here is my old comment on this and the submitted article from which the information was taken: https://news.ycombinator.com/item?id=27009678 https://news.ycombinator.com/item?id=27009678