they've been reluctant to deploy that autonomous underwater vehicle with the side scan sonar that could characterize the bottom. i guess they're trying to keep it quiet down there so the tow can be quiet to detect the pings. >> as we look at this animation again and you see where the tow ping locator is. they were saying the area that can be covered by the tow ping locator in one day, if you out the autonomous underwater vehicle down there it's so much slower, so much of a more difficult task, that would take six to seven days with a tow ping locator can do in one day. kind of helps us understand why they're not yet putting it down there. >> right. they're trying to narrow it down as much as possible. they're trying to get that last last few bits of signal before the battery is completely dead, before they've convinced themselves that the battery is dead, there's no chance left. then they will deploy the underwater vehicle. >> when you take all of this under consideration, the depths,