The race to the bottom of the sea is on. Oceans cover slightly more than 70 percent of Earth’s surface and comprise some 97 percent of its water. The oceans also have currents that move through and over them in ways that directly impact our weather, and therefore, our lives.
We know there are deep-sea mineral deposits worth exploring, too. We just don’t fully understand which minerals those might be, the quantities available, where exactly they are, nor how to get to them. But we are trying to find out. In April, President Trump issued an executive order recognizing security and economic upsides in deep-sea science and technologies. He ordered expedited licenses and commercial recovery permits for deep-sea exploration.
Despite the national security implications and the minerals’ ubiquity and potential value, humans have only been able to explore about 20 percent of the world’s oceans. The reason is simple: The ocean floor is almost an exact replica of Dante’s Ninth Circle of Hell. It’s cold, dark and crushing.
Still, as one of Earth’s only remaining untouched horizons for exploration, the siren song is strong and pulling some intrepid innovators in – some for the sake of exploration and some for the lure and potential of untold riches. To go further, the first step in either of those processes is gathering information about the environment. Deep-sea mining companies around the world are chomping at the bit (chomping at the boat for the shark equivalent of that metaphor) to learn as much as they can.
Deep Sea Sight
One of the barriers to subsea exploration is the physics of how energy travels in water. Light gets backscattered and attenuated, making it hard to see objects and distinguish colors. This is a problem for our human eyes and even most cameras. A group out of the Massachusetts Institute of Technology has previously tried to color-correct images taken underwater using an algorithm called “Sea-Thru,” but it is very computer intensive. The group has now released a newer algorithm called “SeaSplat,” which appears promising. It goes through the image pixel by pixel, determining the effect backscatter and attenuation had on the image and computes what the true color of that pixel must be.
This new pixel by pixel algorithm has been combined with a 3-D Gaussian splatting method to paint a 3-D image of the subsea environment from a series of 2-D images. The 3-D method has been previously vetted using image sets from above the ocean, but its undersea use was limited due to the aforementioned issues with color and sharpness. The pixel correction introduced for SeaSplat helped bring the method below the waves with good results across multiple bodies of water.
Underwater Real Estate
Sending remote-operated vehicles to take deepwater images is one thing, but it’s hard to replace the value of placing humans directly on the seafloor. We do this for activities including upkeep and maintenance of our subsea infrastructure (think subsea cables) to exploration.
That said, we perform subsea dives sparsely and at limited depths for many obvious reasons. The lack of light is one, and others revolve around the crushing pressure and the difficulty of crafting a wet suit that won’t give way under it. There’s also the risk associated with decompression cycles. To get humans down there, we pressurize their dive suits, but such an action impacts the way our bodies absorb nitrogen. Depressurizing from those suits as the diver comes up can be a risky process, and the risk increases with each cycle a diver goes through, making a decrease in the number of depressurization cycles a key aspect of increasing the safety of subsea exploration.
One company, DEEP, seeks to tackle this issue by giving people underwater habitats to live in, allowing them to stay in the subsea for longer periods of time. They have created several innovations to stabilize their habitats in deepwater conditions, including Wire Arc Additive Manufacturing, which efficiently creates the necessary structures that will support the constant pressures. DEEP also uses modular components that allow fit-for-purpose designs spanning a number of timelines. The company is currently testing some pods in the waters near the Scottish Highlands.
Bubbling Batteries
A scientist seeking to study the ocean’s oxygen gradient stumbled upon another seafloor mystery when he noticed the oxygen content of the water increasing when it should have been decreasing due to a lack of light to drive photosynthesis. Andrew Sweetman, deep-sea ecologist with the Scottish Association for Marine Science, sought a reason for the seemingly antithetical measurements and discovered subsea “batteries” emitting small but measurable amounts of electricity – roughly .095 volts. He suspects they might be the source of the extra oxygen.
The “batteries” are polymetallic nodules that the mining community has long been eyeballing, but the potential that they might be emitting oxygen adds a new layer of complexity, because removing them could have unpredictable and cascading effects. The measurements aren’t without their doubters, however. Olivier Rouxel, a geochemistry researcher at the French Research Institute for Exploitation of the Sea, said there was “absolutely no consensus on these results,” and has given the possibility that the oxygen measurements were conflated with trapped air bubbles rather than something significant.
With the surface of subsurface exploration just being scratched, we geoscientists might have an exciting set of decades ahead of us.