As deep as it gets, unmanned
How Russia sent an unmanned submarine to the Mariana Trench

Last year, Russia sent its Vityaz unmanned submarine to the deepest depths in the ocean.

The Vityaz is an autonomous, unmanned underwater vehicle that Russia’s Rubin Design Bureau was commissioned to develop as a concept by the Russian Foundation of Advanced Research Projects for Defence Industry. And on May 09, 2020, the Vityaz surveyed the Mariana Trench, at a depth of more than 11 kilometres.

Now, this is not the first submersible to have explored the Mariana Trench, but it was the first autonomous vessel to complete the mission, which, in itself became a test of the emerging standards of, not only, hull design and communication but also Artificial Intelligence (AI), according to Dmitry Semenov, Chief Designer at Russia’s Rubin Design Bureau.

Speaking at the International Maritime and Defence Show (IMDS) 2021 held at St. Petersburg last month, Semenov explained the feat required them to solve these three fundamental problems. First, they had to design a hull that could withstand the pressure under 12 kilometres of ocean. The second was embedding Artificial Intelligence (AI) into the control of the Vityaz so it could carry out its mission, depending on emergent conditions. And the third was to be able to maintain constant communication with the vessel, persistent enough for an operator onboard a mother ship to be able to take over control at a moment’s notice.

“It’s fantastically high pressure. Just try to imagine how high is the hydrostatic pressure that is exerted upon the hull structures, considering that the depth is 12 kilometres,” he said.

Why 12 kilometres?

“Officially the Mariana Trench depth is around 11 kilometres. So we made provisions for a safety margin. And when undergoing hydrostatic pressure trials for this vehicle, we exerted them to pressure equal to that at a depth of 13 kilometres, explained Semenov.

[stextbox id=’stratpost’ color=’ffffff’ bcolor=’000000′ bgcolor=’000000′ bgcolorto=’000000′]12 kilometres is roughly four leagues, if we’re taking the Jules Verne classic as a reference.[/stextbox]

The Vityaz is heavy.

“This titanium structure weighs around 4 tons, so if we try to imagine how it’ll dive — it’ll just drop to the bottom of the ocean like a stone,” he said.

Rubin’s designers had to ensure that the 4-ton titanium structure would float. And because of the relatively smaller structure of the Vityaz, compared to manned submarines, it was ‘physically impossible to arrange and allocate all the systems related to tanks, pipelines and so forth,’ that would be typical in a manned submarine.

And besides ‘special work on the sealing arrangements of the hull structures’, Semenov explained, “What’s most significant is the coating material you see here, which is of red colour. This is a spheroplastic coating material that functions as a life jacket.”

“It’s a very lightweight spheroplastic material all around the 4-ton titanium structure that brings it to such a level of buoyancy that makes it possible to keep it afloat and achieve zero buoyancy,” he added.

The next clever bit is enabling a level of autonomy for the Vityaz to carry out its mission without operator input or guidance.

This was the first time an underwater vessel was to carry out a mission over a period of 24 hours, completely autonomously, using Artificial Intelligence at a depth of 12 kilometres, not counting the time for diving and surfacing.

“This vehicle is capable of being absolutely autonomous and absolutely unmanned, without any intervention of an operator,” said Semenov.

‘The trajectory of its route is pre-loaded in the algorithm of the Vityaz’ and it is ‘pre-tasked in advance with the sequence of actions involving the activation of the instruments’ he explained.

“The Vityaz autonomously decides when to, for example, descend to the ocean floor, when to change over to the next stage of the mission, when to switch on or enable radar electronics or antenna or the sonar or do this or that part of the mission task,” said Semenov.

Now, the Vityaz doesn’t have any physical link to the mother ship. But Semenov explained that ‘the crew onboard the mother ship are continually updated on what is going on onboard Vityaz and can intervene at any given moment to carry out the mission, in case of an emergency or if it’s planned for the requirements of the mission’.

“The communication with the operator is through hydroacoustics — through sonar. There are a number of hydroacoustic antennas installed on the hull and each of these antennas have their own purpose as per the requirements. Each antenna maintains this or that kind of communication with the mother ship,” explained Semenov.

“Before the 9th of May of 2020, we did not have any reliable data on how these hydroacoustic signals might behave through the thickness of that water at such an extreme depth of 12 kilometres,” he said.

Rubin’s designers had an idea of how ‘the principles of dissipation of such signals work at the depth of six kilometres, for example’. “What happened deeper was a mystery to us. We did not know. And, actually deep in our heart we were prepared that we might lose communications with the Vityaz,” said Semenov.

So how did it turn out?

“For all 24 hours of that day, we were at any given moment aware and updated on the exact location of the Vityaz and the current stage of its mission. The hydroacoustic signal was always present throughout these 24 hours,” explained Semenov.

And now?

“With the success of this project, the Russian Foundation of Advanced Research Projects for the Defence Industry extended this contract with us and now the vehicle’s undergoing a deep upgradation program. It’s being equipped with even more modern and efficient equipment. Each piece of equipment for this vehicle needs to be designed from scratch because there are no equivalents to the equipment required to retain its capability at such depths,” said Semenov.

Right now, there are two models of the Vityaz. The upgrades are intended to not only install more capable equipment onboard the Vityaz, but also add new equipment to gather additional quantities and types of data when it is dived.