for those who don't understand how a search goes about in the ocean, why can't they just turn it right around, nail it down and send down that bluefin underwater autonomous vehicle, and take pictures of exactly what was sending out that signal? please explain. >> well, the ocean's a very unforgiving place. so this requires. >> reporter: deliberate, very patient operations which is what the experts on the "ocean shield" are doing right now. first as talked about in the previous segment, just the thought of turning that shim around with the pinger deployed with thousands of miles with cable out is taking three hours. it's not like in your car where you turn the wheel and you get around the corner. it takes a long time to get all of that equipment turned around and back on the right bearing. secondly, they need to know what is on the bottom before they send down a bluefin 21 which is a very expensive piece of equipment. they need to do some bottom mapping down there that's going