our science correspondent jonathan amos has more now on what the investigators will be looking at. we have some idea now of the debris and what was seen on the ocean floor close to the titanic, about 500m get of that old ship. this is the titans sub, about 7m long. it has a pointy end, they found a part of that. they found their slanting structure which enables it to sit on a flat surface when any workshop like this, and they also found the titanium endcap that has the porthole, there are two of these. in the middle is where the focus of the investigation will probably be, because the cylinder is made of carbon fibre, not the usual material that they construct such