I wrote it was a perfect shoot down because pieces of the spy balloon could be salvaged. Nothing I have read has changed my mind. The military can not divulge a lot of their information, but have made it clear that this is not an isolated case. We will learn very valuable information from the debris which includes the balloon itself and as much as possible the hardware inside.
When the balloon was first observed, it was over the Aleutian islands in the Bering sea. Mean depth of the Bering sea is about 5,000 ft, but the Aleutian trench, approximately 100 miles long and 50 miles wide, has a maximum depth of 25,000 ft. The shifting sheets of ice and snow are enormous and finding even pieces of the balloon was be extremely difficult.
Biden did the right thing as he gave permission for the military to shoot the balloon down, when they could do so without endangering Americans. It was then a technical decision of when to shoot it down. The Generals would turn to “modelers” for some estimate of the size of the debris field and the potential damage that could be done with falling bits of hardware. I know this field, because I spent a lifetime modeling physical phenomena. If one knows what is falling and has some prior experience with similar incidences, then analysts have something solid to build their models. In this case, there was only very limited information of what was shot down, and certainly no prior analogous experience.
So, prior to the destruction of the balloon, it would be very hard to know where pieces of metal might land and cause harm to residents below. So, when they were deciding the right time to shoot down the balloon, they were dealing with a debris field based on just a bunch of guesses. Intelligent guesses, for sure, but the hard data were missing.
But, now there is a debris field, much of which is yet to be discovered. Currents will distort the field, so the modelers will still have to factor this into their analysis. In the modeling world, the forward solution is to project from 10 miles in the sky down to the impact on the ocean surface. This solution is then can be refined when the debris is found. This can be called the inverse solution, or model validation. Modelers will undoubtedly try to assess the uncertainty in results. This is called sensitivity analysis.
From various sources, the debris field is likely in terms of miles. Pieces of the big white balloon were easy to find as I expected. The modelers will be hard at work, adjusting their models, to help the dive teams and unmanned subs to search of the pieces of debris.