Do scientist consider small asteroid/stones/junk in space while sending satellites to orbit or for long range missions like for Mars?
If yes, then how can they identify the trajectory and prepare those satellites/mission from future attacks? If no, then how satellites manage to travel so fast without hitting any obstacle?
Whipple shields or derivatives are used to protect against very small objects, and big sky theory along with knowledge of the relative size distribution (which is heavily weighted toward the small end of the scale) predicts very low chance of collision with larger ones. The largest ones, those that can be mapped from Earth, are relatively few in number and their orbits can be predicted to reasonable accuracy for months and usually decades in advance.
Since there are so many possible causes of failure in spaceflight, the chance of collision with an unseen object that the shielding cannot handle is only one of many risks of mission failure, and not the largest.
