Titan sub remnants found

The disappearance of the Titan submersible, en-route to view the wreck of the Titanic, 4 kilometres down and about 400 miles offshore has dominated the news this week. Contact with the OceanGate sub - and its crew of five - was lost on Sunday as it made a descent to Titanic in the Atlantic Ocean. The tail section of the Titan has reportedly been spotted since, suggesting that the sub may have imploded under the intense 400 atmosphere pressure down close to the sunken ship. Chris Smith spoke to Frank Owen, retired navy commander and former director of the Australian Submarine Escape and Rescue Project…

Frank - This was an expedition mounted where they sought paying guests to go down to see the Titanic. We know that the conditions and the planning had meant that there was only going to be one expedition possible this year. There were two planned for 2024 and we knew that the weather had been unsuitable for proceeding with the mission until a window opened up on the Sunday at which time they dived. They lost contact an hour and 45 minutes into the dive.

Chris - And do we know the nature of that contact when we say they lost contact, you can't talk on the phone when you are underwater. So what was the nature of that contact?

Frank - They have a through water information link. It's similar to a modulated wave that passes on a carrier wave which includes some communication elements, so they're able then to pass text messages between some support vessel and the submersible. There are similar systems like that in the military actually.

Chris - So if contact was lost at that time point, how deep would that put them at the point at which contact was lost?

Frank - The whole trip is supposed to take eight hours and you'd imagine they would take perhaps two hours to get to the bottom, four or five hours circling looking at the wreck and then the rest of the time to return to the surface and be recovered. It would probably take longer to be recovered than it would be to be launched, so I would think that they were quite close to their intended depth when communications were lost.

Chris - Obviously communications could be lost just because something has malfunctioned, it doesn't mean that they were in jeopardy at that point, but the fact they haven't returned argues something has gone wrong. When you are nearly four kilometres underwater, what is that like for a craft to have to tolerate and take and what are the currents like? Tell us about the environment at that sort of depth.

Frank - Most of the current is going to be up towards the surface. You've got things like the Gulf Stream going past. It's not immediately in the Gulf Stream where they are, otherwise you wouldn't have a lot of icebergs that were there when Titanic hit it, of course. But it is in an area where you do have surface currents that are moving around. The current down near the seabed would be much less the temperature and in that sort of water column would tend to be perhaps 10 or so degrees at the surface and it'll stay about that temperature until it gets to what they call the layer, which will be around 200 metres. At that point, the temperature takes a sharp drop and within about a thousand metres or so, it'll drop from that 10 degrees down to the two or three and then it'll stay isothermal or the same temperature all the way to the bottom. What that barrier does that break is that it really affects the passage of sound through the water. So sound that comes down to that depth will then be refracted downwards and it creates a barrier underneath this layer where it's very difficult to hear things.

Chris - And I guess that means it will be very difficult to penetrate that layer with the sort of sonar that can explore the sea floor even if you had one powerful enough to get over this sort of distance. Which at the moment most boats aren't endowed with that, are they?

Frank - No, they're not. And really at 4,000 metres you might get an echo sounder telling you what the depth is, but that's a sort of brute force. You won't get an imaging sonar getting anywhere near through that.

Chris - Has anyone ever recovered anybody or anything from these sorts of depths before in your career as a rescue operator? Would this just be totally unfeasible?

Frank - No, it's not unfeasible. The US Navy has recovered vehicles and aircraft from that sort of depth. They've recovered an F 35 from even deeper than this. Once that sort of vehicle is down at that depth, as long as it's within the pressure rating, it can actually then work as if it's doing its main job. The biggest challenge that an ROV faces is the drag because it's trying to drag the umbilical against the current for all of that 8,000 metres. Once the umbilical itself is bent by the force of the current…

Chris - This is the cable and the tether that these remote vehicles that you would seek to rescue with are on back to the the ship on the surface, isn't it?

Frank - Yeah. So the tethers are going to be in the order of a diameter of about 50 millimetres, perhaps more. If you look at the surface area of 50 millimetres by 5,000 metres, you end up with the frontal characteristics of several big trucks. So it's trying to pull all of that weight through the water.

Chris - And these poor people who've been trapped inside this submersible. If one finds oneself in that sort of situation, is there anything you can do to maximise your chances of survival?

Frank - Yes, you can rest. The best thing you can do is lower all parts of your metabolism. So the best thing to do is sleep. If their body temperature really drops down in a way that's a good thing because what will happen is everything will slow down, their heart rate will drop, they won't breathe as much, they therefore won't consume as much oxygen and they won't generate as much carbon dioxide to eke out all of the benefits of the air purification system that they have.

Chris - This sort of mission in this sort of vehicle. What's your reaction when you saw the news and what was going on and who was doing what would you go to sea in that?

Frank - Especially with what I know now, I don't think I would go to see in that craft. It doesn't have the redundant systems and emergency systems that I'm very familiar with, with other vehicles, including the vehicle that we developed in Australia for the submarine rescue system that we had, which had on its roof on the top of the vehicle radar reflector, it had strobe lights, it had radio transmitters, and they would've been used to be able to communicate with searching forces. It also had transponders, or beacons, that could make a ping to alert people to where it's lost when it was diving. So those sorts of systems aren't needed in the day-to-day running of the vehicle, but they're very important when things go wrong and I don't see evidence of them in the titan.