The first attempt with the Genesis probe ended up with half the contents splattered across the Utah desert.
Of course it was later taken to the "clean room".
The latest Pluto probe (Pluto might not enjoy that) contained 22 pounds of Plutonium which NASA judged had only a 1 in 350 chance of being scattered across the globe in the event of a launch accident.
It seems the philosophpy of NASA is that if we mess up this planet, well no problem we'll just go out and find us another one someplace.
The neo cons reckon that we are in the end times anyway and it is all god swill (Devil made me do that)
Why Wurry?