By James McLean, director of Zenocean
PREVIOUS articles considered the potential for autonomous vehicles being resident offshore, laying up subsea between ops or for recharging, uploading/downloading data or being controlled from a shore base with control routing through an offshore buoy, a platform, a USV or even airborne drones.
Subscribe to our daily newsletter
Why? Free to subscribe, no paywall, daily business news digest.
Recent advances have recently seenSaipem winning an award for its new Hydrone-R underwater intervention system. They suggest the vehicle has the ability to remain submerged for up to 12-months, hosted on a subsea docking station for battery recharging or data up or downloading. It can be operated remotely from onshore, or in fully autonomous mode has a working radius of some 10km.
Kongsberg Maritime are now offering their HUGIN Endurance Autonomous Underwater Vehicle intended for remote subsea survey projects. At 1.2 metres diameter, 10 metres long and weighing in at 6000kgs it’s a sizeable machine. It can be operated from shore-to-shore, and is capable of 15-day missions with a range of some 1200km, driven by lithium ion batteries. Future versions may be delivered with new battery technologies and offer even greater mission endurance capability. HUGIN is available in different configurations but will operate to 3000, 4500, or down to as much as 6000 metres and is designed to be able to travel from 1 to 8 knots which is hugely impressive.
It can be used for a vast range of tasks, including, for example; high-speed seabed mapping to pipeline and subsea structure inspection, oceanographic, environmental and marine, seabed minerals and geological surveys, to mine countermeasures, intelligence, surveillance and reconnaissance works. It has three operational modes – autonomous, semi-autonomous or supervised.
Autonomous requires no operator input and follows a pre-planned route meeting objectives along the way. Long endurance autonomous missions have now become a reality with the introduction of a new level of inertial navigation system performance. A semi-autonomous mission follows a pre-planned route, but allows the operator to monitor mission status and update the mission plan and set new objectives. A supervised mission provides the operator with real time payload data for quality management and also ensures best position accuracy by updating Hugin using Kongsberg’s HiPAP USBL positioning and communication system.
To put the vehicles 1200km range into perspective, it could travel from Egypt to Venice, or Sydney Australia to Auckland New Zealand without the need for expensive surface vessel support. It is the case that greater depths and distances for controlling underwater vehicles is, and will continue to become the norm, but how about a billion miles, with journey times of seven years?
NASA have declared they are considering sending a submarine to planet Titan, a huge moon of Saturn. It could be ready to launch as early as the 2030’s. Unlike the North Sea, rather than exploring ‘for’ hydrocarbons, they would be plumbing the depths ‘in’ vast frigid quantities of hydrocarbons – methane and ethane, as well as liquid water. It is thought that control could be effected via an orbiter or even routed through some kind of vessel dropped on to the sea surface.
Titan is 3,200 miles wide and is the second-largest moon in the solar system and is the only world beyond Earth known to host stable bodies of liquid on its surface — the lakes of liquid methane and ethane are larger than the Great Lakes of America.
Titan is huge for a moon, but way smaller than Earth with 14% of our gravitational pull, thus exerting much less pressure on a subs hull than at the equivalent depth on Earth. To accommodate the necessary communications equipment, a standalone sub would need to be around 6 metres in length, weighing in at around 1,500 kilos, whereas one with a partner orbiter, the instrumentation could fit a much smaller sub at around a third of the length and a third of the weight.
The two most likely exploration targets are Kraken Mare and Ligeia Mare. Both of these bodies are enormous. Kraken Mare covers about 154,000 square miles (400,000 square km) and is at least 115 feet (35 m) deep. Ligeia Mare has an area of 50,000 square miles (130,000 square km) and a maximum depth of 560 feet (170 m).
Titan has seasons that last around seven Earth years apiece. Any mission would be best placed in the summer when a spacecraft could image shorelines in visible light and communicate directly with mission control on Earth. It is thought a 2040-2045 arrival would be a good choice if the mission included an orbiter for communications. As the journey would take around seven years it dictates a launch in the 2030’s, otherwise NASA would need to wait another three decades for the seasons to shift!
It would be easier and arguably cheaper if the researchers were content to stay on the surface with some kind of craft and probe the depths intermittently with small, instrument-laden devices called dropsondes. Such devices are regularly used for atmospheric research where they are dropped from aircraft at altitude over water to measure storm conditions as the device drops through the air column. The rewards would be less utilising this method, so the submarine idea offers the best, albeit much more expensive solution.
It seems to me however that Kongsberg already have a platform in Hugin upon which to base a submarine mission. The power plant would need to be nuclear rather than lithium ion batteries, but other than that it’s a case of ‘Its space Jim, but not as we know it’
