flow. jon: the blowout preventer is supposed to do just that, it's a big valve on the seafloor, right? >> it's an assembly of valves, 14-foot square, 18-foot tall, weigh six to 800, a thousand pounds, and there will be three devices in it capable of closing off. jon: why didn't those work to prevent whatever led to the actual explosion and fire? >> there's no indication at this time of what happened, but obviously, some control -- something in the control circuit, operational circuit did not happen. jon: so if the subs can get down there and just turn some valves, this thing could be essentially over for now? >> depending upon how this was set up, it may be as sinkel -- simple as turning one valve, there may be a hydraulic line and pressuring to make it happen or it may be required to remove a hose and attach a hose connection to the field