That's why you launch a few of them. Also, the odd's of the probe getting destroyed e.g by an impact are really low. They get lower once you leave earth orbit a

That's why you launch a few of them. Also, the odd's of the probe getting destroyed e.g by an impact are really low. They get lower once you leave earth orbit and really low when you hit interstellar space. And you can probably get to less impact stuff quicker if you go perpendicular to the plain of the ecliptic rather than out. Your bigger issue is component failure. So launch a enough to deal with component failure, wait long enough for them to be out of harms way, and then you have a time lock. Sure it's expensive, but time locks with a known time to unlock or even a decent estimate are not really possible algorithmically.