If I own a field, and stuff falls out of the sky onto my field, what do the laws say about ownership? I believe that stuff which washes ashore from shipwrecks is generally "finders keepers", but I don't know if there are special rules for aircraft or spacecraft. That being said, I can't imagine anyone not affiliated with the crew wanting any such item. Of course, I can't really imagine anyone wanting coal from the Titanic but I've seen it advertised for sale.
Good point, and as a respecter of property I agree. I feel my property begins at Earth's center, radiates outwards to the boundaries of my property and extends up to 500 Feet.
But I recall there has always been some kind of law regarding keeping things like weather balloons, etc., and of course, this stuff is forensic evidence, so I would expect that would trump property rights.
PS: I have not tested my property doctrine by firing at low flying aircraft. Yet. :-)