Deep sea Vehicles

This is one of the only vessels on the planet capable of reaching the oceans' deepest locations, and it can do so while sending back high-fidelity data that could vastly broaden our understanding of what goes on below. Yet, despite the promise of Nereus and the other vehicles in the WHOI fleet, as well as those created by other institutions, there's little doubt that deep-ocean research has, until recently, barely registered on the national consciousness.

After all, just before the recent celebration of the 50th anniversary of the first--and only--manned mission to the bottom of the Mariana Trench (at 35,800 feet the deepest spot on Earth), Don Walsh, one of the two men who had taken that trip, told CNET News, "We were happy to be the first, but we didn't expect to be the last."
Nereus
To talk about Nereus, I've come to meet with Andy Bowen, the director of WHOI's national deep submergence facility.
Until now, Bowen said, most of the world's deep ocean exploration energies have gone into probing at no more than 6,000 meters below the surface. That's because, he said, 98 percent of the world's seafloor is above that level. The remaining 2 percent has largely been inaccessible. "We tend to look in the easy places first and the hard places last," he said.
The history of deep-sea submersibles has been about two kinds of vessels: Autonomous underwater vehicles (AUVs), which are designed to explore wide areas of the deep, mapping as they go and providing scientists with broad looks at the ocean floor; and remotely operated vehicles (ROVs), which are tethered to a surface ship and which transmit data--photos, video, and more--back over some kind of cable.
But Bowen explained that as scientists probe deeper and deeper, the costs of the exploration has traditionally grown, given the need for more sophisticated and rugged equipment.
With Nereus, though, that changed. When the vehicle initially launched, in 2007, it represented the first of a new generation of hybrid ROVs that can trail a fiber-thin tether up to 25 miles and can roam much wider areas of the sea. One major innovation of Nereus is that, for the first time on a very deep-sea submersible, the major power source for the vehicle is stored on-board.
And traditionally, Bowen said, surface ships have dangled their tethered cables to ROVs below the surface, largely confining the exploration area to one the mother ship can navigate above. With Nereus, and its ultrathin cable, it's possible to let the vehicle roam far away from the surface vessel, giving it a far, far greater zone to explore.
At the same time, because Nereus is much lighter than its traditional deep-sea cousins, Bowen explained, it requires much less surface infrastructure--meaning smaller motherships--and therefore, a great deal less financial investment for a mission.
Why go deep?
By freeing up Nereus to roam far afield from its surface ship, its developers have made possible entirely new kinds of research, Bowen said. For example, by allowing the vehicle to go wherever it wants, scientists can now conceivably send Nereus on survey missions under the Polar Ice Cap--something that was never before possible.
In the past, because of the movement of polar ice, it would have been near impossible to get a dangling ROV to stay still long enough to learn much at a specific point. But now scientists can allow their icebreakers to flow with the ice and simply let Nereus get further and further away, essentially standing still in one location while the surface ship moves with the flow.
"Vehicles like Nereus can maybe change the game," Bowen said, "as to how science under the sea can be performed."
The major remaining limiting factor? As always, it's funding. And until significant money comes in--from government, industrial, academic, or private sources--Nereus will sit on blocks at Woods Hole.
Still, Bowen thinks what Nereus has proved is that this new kind of sea exploration is possible, but that it doesn't have to be aimed at the deepest spots in the ocean. Perhaps, he argued, those interested in investing in such science can focus on areas no more than 4,000 or 5,000 meters deep, research that could require vehicles that cost just fractions of what Nereus cost. So for the investment of another Nereus, it might be possible to pay for several vehicles, each of which could still accomplish a tremendous amount of research.
It might not be as sexy as being able to enable surveys of the Mariana Trench, but it's still great science.
 

Wireless communications underwater
Until now, all the communications between the mother ship and the underwater vehicle had to be done through some kind of cable, be it copper or the new-style ultrathin fiber.
But Bowen said pioneering research is being done into new LED-based high-band wireless communications that could, for the first time, enable an ROV to be free of even the fiber-thin tether. That's still in the future, but the goal is clear, he said: autonomy for the robotic underwater vehicle.
He explained that even this potential LED technology would have limited communication abilities, but that could be offset by integrating much greater autonomous technologies on board the ROVs, meaning the vehicles could make more decisions on their own and yet still send back meaningful data.
 

Cost of a Space Shuttle mission
To another WHOI researcher, Hanumant Singh, an associate scientist in the institution's deep submergence laboratory, the question to answer is how can the value of the underwater vehicles be best made available to the public when the entire world's annual spending on ocean research is about the same--roughly $500 million--as a Space Shuttle launch.
That means, of course, that there simply aren't many research opportunities to go around. And one of the limiting factors has been that most of the existing resources have very specific capabilities--something that's great if you're trying to solve a single problem, but not very helpful if you want to do general research.
What makes WHOI different than other institutions around the world, Singh said, is that it may be the only one that works on both the sensors that gather data, and the platforms on which the sensors are built.
That means, for example, he said, that no one else could do what WHOI researchers did: Not only a full survey of the Titanic, but one with very high-resolution imaging.
And since WHOI is all about doing good science, one of its goals, Singh argued, is to develop the technologies--the hardware and the software, as it were--and then put them in the hands of researchers at other institutions all over the world. So, he recalled, he once told scientists at the National Oceanic and Atmospheric Administration (NOAA)--scientists he was giving one of his vehicles to--that he hoped to make himself obsolete: By extending NOAA's capabilities, Singh hoped to not have to be required on their exploration missions in the future.
"We say, 'We will give you all the software and the design,'" Singh said, "so you're empowered to fix anything" that goes wrong. In other words, WHOI will not only provide competing organizations with its technology, it will also show them how to use and maintain it.