For those out of the loop, the Titan was an experimental vessel meant to dive to depths of around 13,000 feet, specifically to visit the final resting place of the Titanic. Tragically, it imploded on the way down on its last voyage, taking all of its crew with it. The Titan was made of carbon fiber and titanium, designed to be steered with a plug-and-play controller, and used an electric engine. You may be wondering why everyone is questioning their navigation system, and lack of backup comms.
Firstly, The Pinnacles Of Submersible Technology
To say the Titan was unusual in the field of submersibles is a vast understatement. So to truly get the basics, it’s better to look at everyone else’s submarines and submersibles first, alongside the physics of water. Water, especially salt water, is actually really good at absorbing radiation! It’s how life was able to survive in the water even when the Earth lacked an ozone layer. The ocean soaks up electromagnetic radiation and disperses it far before it can reach the depths submarines get to.
This holds true even though most subs aren’t made to reach the deepest parts of an ocean. Strategically, 800 to 1,000 feet is plenty deep enough to hide from surface vessels, so most military subs don’t bother going any deeper. In exploration terms, unmanned vessels equipped with cameras are generally better for observing wildlife or underwater structures, although there are a variety of submarines and submersibles designed to hold people and reach further depths. James Cameron has famously reached the Challenger Deep, the deepest point of the Marianas Trench, as well as multiple dives to the Titanic in his submarine The Deepsea Challenger.
How do those boats communicate? There are a variety of methods, but one of the easiest methods for communicating with others on the surface is to simply come up and put up an antenna. Air communicates radio waves much easier. Some crafts use tethers, tied to buoys with antennas attached, so they don’t have to come all the way up to the surface themselves. That allows them to stay further down, and further out of sight of surface vessels if so desired. At depth, options are limited. One such option was ELF communications: ELF, or Extremely Low Frequency radio waves, were used to summon certain submarines to the surface so they could receive longer instructions up until 2004, when the project was shut down in the US. ELF communications were a highly specific tool used for a highly specific task during the Cold War – they ate up an enormous amount of energy and took a gigantic antenna to broadcast (56 miles of cable total) – and as a result they didn’t see much use, with the original project site shut down in 2004 in the US.
How Did the Titan Get Instructions?
Using a buoy with an antenna attached or a tether is simply not feasible at the depths intended for the Titan. Neither is GPS, or WiFi, or ‘true’ text messaging. Instead, the Titan used acoustic pulses (otherwise known as sonar), where packets of data are sent down as sound waves, and a hydrophone on the receiving party’s vessel is able to catch and decipher the packet for the people inside. All of the messages the Titan team sent or received were meant to be short, coded messages with no room for confusion. A laminated sheet inside the vessel provided translation, according to a photo from David Pogue.
However, such a system with few navigations tools on the craft itself made it easy for the submersible to get lost. While the craft had sonar, it wasn’t the sort they could use to bounce off of obstacles to navigate, so they were entirely reliant on the surface vessel for eyes. Additionally, the boats could only talk when the surface vessel was directly over the sub. Think the difference between planning a route using a paper map of the highways to travel on and using a GPS – the CEO even compared it to a game of Battleship, where the top ship gave directional instructions using a grid system. Taking an unmarked exit on a highway using a paper map means re-orienting yourself on a landmark to get back on track, but underwater, there just isn’t much to orient with. The Titan was reliant on the topside vessel knowing where it was on their battleship grid to steer it, and with no real landmarks outside of the sunken ship itself, getting ‘lost’ in the water at those depths happened surprisingly infrequently for how low-information that system was.
Unfortunately, even in the event the craft was recoverable, there just aren’t great ways to send signals back and forth and guarantee someone will receive them. Acoustics powerful enough to communicate with anything anywhere on the surface (not just directly overhead) eat up a lot of electricity, and so wouldn’t be a reliable backup if the sub had lost power. Radio waves are out until the craft ascends. ELF only works one way. Once any craft is deep enough in the water, it’s alone!