passive and active sonar. they re really sensitive. this is used to track other submarines, hunt and kill russian subs. sonar systems are super sensitive. it gives more range because it s faster and better capability to find things. absolutely. the listening bit, it s listening for pings. as we pointed out we re down to the last few days of this now. we know from experts, the battery life could last up to 40 days. we re nudging on that final ten days. could be 20 days based on how they re stored. the pinger running out of juice if it has any left. and it was functions right. coming up next, the shooting at ft. hood raises so many questions about mental health, what the
miles away tomorrow. so the most inaccessible spot you can imagine on the face of the earth. if there is anything down there, we will find it. i want to bring in cnn s tom foreman, doing such a great job of virtually showing us the circumstance we are in and how it changes day to day. tom, we were just talking about an underwater crime scene if we ever get to that stage. and what it s going to be like for mariners to have to do this. where we re talking now is incredibly different than the underwater crime scene they mapped out for swiss air 111 off the coast of halifax for flight 800 off the coast of new york. we re in a no man s land. take me there and help me get a handle on whether we can even do this. one of the reasons it s no man s land, we still don t know where we re looking. we still don t know. we talk about the pinger running out on the flight data recorder. we have talked about that a lot. what s also running out here, day by day, all of the intelligence they have on