Don't forget how little we knew about Mars when this craft was designed
We didn't know how deep down to go to find ice, we didn't know how hard it would be, or how cohesive, we didn't know how it would behave, physically.
Now we've found out quite a few things, but it does take a bit of trial-and-error.
Don't panic, They'll probably get it right before something vital breaks.
If not, we'll send another mission. Patience is a neccesary commodity in robotic space exploration...