'Nereus' deep sea research station
With the Aquarius program winding down, the world will soon be without any undersea research platform whatsoever. As oceanic conditions are intimately related to the changing climate, lacking any outpost of observation and study within the sea is scientifically unacceptable. It was also in some sense untenable that we should have an orbiting research station the size of a football field, but an undersea laboratory no larger than a single module of the ISS, and just 60 feet underwater.
In order for the value proposition of a bigger, better undersea research station to be great enough to warrant the considerable taxpayer investment it would require, it would need to offer more than just the saturation diving function of the Aquarius. The 'Nereus' undersea base concept would be located at a depth of a thousand feet, on the very edge of the continental shelf. This is to allow daily excursions by submersible from Nereus to the abyssal plain, to study hydrothermal vents.
A submerged home base for deep diving submersibles would be of tremendous value, as the single greatest difficulty in the use of manned submersibles is unpredictable surface conditions. Even slightly choppy waves make deploying or recovering manned submersibles dangerous and usually cause delays or outright cancellation. A station capable of deploying and recovering submersibles far below the reach of storms would eliminate those considerations and permit the recharging, resupply of oxygen and CO2 absorbant and basic maintenance of submersibles without requiring a fully crewed A-frame equipped surface vessel.
The base would be kept at ambient pressure, with a Hydrox atmosphere. Comex hyperbaric diving experiments in the 1990s demonstrated a physiological limit of 2,300 feet equivalent pressure when breathing this gas, the greatest pressure a human being has ever demonstrated the ability to tolerate. Less than half of that maximum should be perfectly comfortable, the primary difficulty is in replenishing the Hydrox. This can be accomplished by the use of the same compact nuclear reactor found in our Navy's submarines. It would also supply heat, light, dehumidification, and fresh drinking water. Instead of throwing away the hydrogen produced during electrolysis, as on SSGNs, here it would save it and use it to generate Hydrox. This could potentially eliminate the ongoing expense of CO2 absorbant, as the rate of Hydrox generation could be scaled up to the point that it exceeds our rate of CO2 production. Stagnant breathing gas would, as in a shallow water ambient pressure base, simply bubble out the moon pool. Alternatively if that's not desirable the atmosphere could be recirculated, conserving the hydrogen, removing the CO2 in the same manner as a nuclear submarine, and replenishing the oxygen. This is a more sophisticated method not strictly required but certainly possible.
This design would be fully independent of the surface. Because it is ambient pressure rather than 1 atmosphere it does not resist any pressure differential, and so does not need to be reinforced as a pressure vessel. This permits it to be very large at a lower cost, although a diving bell will be needed to transport the crew to and from the surface, along with a deck mounted decompression chamber. This is the same equipment already in widespread use today for oil rig maintenance divers.
Because the crew breathes gas pressurized to depth, any submersible or atmospheric diving exoskeleton deployed from this base would benefit from an extended maximum depth, by 1,000 feet. Thus, a Newt Suit which normally maxes out at 2,000 feet would instead have a crush depth of 3,000 feet, which incidentally is the shallowest depth at which hydrothermal vents are found. This would, for the first time, permit humans in suits (rather than subs) to travel to and study firsthand hydrothermal vent ecosystems, the single most scientifically valuable target for research in the oceans.
These extraordinary capabilities, in my view, warrant the likely pricetag of 50-75 million dollars associated with this undertaking. As we cut military spending, it will free up tremendous money for other, more peaceful and productive endeavors. This should be one of them, so that we do not abandon but rather expand humanity's ambitions to live, work, and study in the deep sea.