Scientists in India, preparing to undertake a dive similar to the one with the Titan submersible in an indigenous vehicle late 2024, say that multiple back-up safety measures for the crew are already in place, though there may be reviews of the safety systems employed.
The Titan, which has previously ferried tourists to view the wreck of the Titanic buried 3,800 metres in the North Atlantic, lost contact with its mothership, Polar Prince, on June 17. Unlike submarines that can stay underwater for months and independently travel between ports, submersibles are relatively low-powered and must be ferried to a specific point in the sea by the mothership from where they are lowered into the sea with the crew bolted inside. After the dive, the submersible resurfaces and the crew is brought back to the ship.
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The Titan consists of a carbon-fibre sphere with titanium casing on the front and back. There have been concerns on the use of carbon fibre and the vessel not being certified to the highest safety standards and OceanGate, the company that manages Titan, has reportedly faced litigation in the past for these aspects. “When we were in the planning stage, there was a proposal to use carbon fibre for our submersible but we eventually firmly ruled it out and have insisted on a titanium enclosure,” said G. Ramadass, Director, National Institute of Ocean Technology (NIOT), Chennai which is in the process of designing the submersible, Matsya-6000, that will take three Indians to a depth of about 6,000 metres into the Indian Ocean, at a point about 1,500 km away from Kanyakumari. “Carbon fibre is strong but is not fracture-resistant. At these depths, any thing other than titanium is not recommended, “ he added. Matsya-6000 also has syntactic foam, a flotation device that would rise to the top and help determine the physical location of the submersible, even if it was unable to resurface. All research missions globally relied on titanium, said Mr. Ramadass.
Ahead of the main dives, likely in December 2024 or early 2025, the NIOT divers will undertake several test dives up to 500 metres inside another submersible made of steel. Titanium is stronger than steel but many times lighter – a key criteria to ensure that the submersible can resurface with relative ease from the depths of the open ocean. While the choice of material – steel, carbon fibre or titanium –is made depending on the depth and the cost involved, it’s also crucial that the submersible’s hull be made perfectly spherical, so that extreme pressure at the ocean depth is evenly balanced. “Even the slightest imperfection, say even a millimetre off, can immediately crush the vehicle. It will go off like a bomb,” M. Ravichandran, Secretary, Ministry of Earth Sciences (MoES), told The Hindu. The MoES is the parent body of the NIOT.
The communication system that will be used in Matsya-6000 is the ultra short baseline acoustic positioning system (USBL). This allows the mothership, which has a transponder attached beneath, to send pulses and the travelling submersible to send pulses back. This will then allow the ship to determine the depth and orientation of the submersible. An acoustic sonar system was present on the Titan, though information on the specific kind couldn’t be ascertained.
D. Sathianarayanan, a senior scientist at the NIOT and closely involved with the operations told The Hindu in an earlier interview that it would be possible for those inside the submersible to sporadically communicate verbally via an “acoustic telephone”. As the depth increases, however, voice messages would be increasingly garbled.
“This accident will certainly have us review and re-check all the safety measures that we will be incorporating in our mission. The big mystery in the case of Titan is why it is impossible to locate the submersible, despite several communication systems on board. So it is possible that future submersibles will have the equivalent of the black box on aircrafts that will help learn the cause of such an incident,” Dr. Ravichandran added.
A key lesson that emerged is the necessity for repeated testing. “We have multiple tests in place before the main dive just so we know what all can go wrong,” said Mr. Ramadass.