January 23 – Fathoms below

Today’s Factismal: Jacques Piccard and Don Walsh reached the deepest part of the ocean in the bathyscaphe Trieste in 1960.

Quick – which has had more visitors: the bottom of the ocean or the surface of the Moon? Though there have been twelve people who walked on the surface of the Moon, there have only been three who have visited the deepest part of the ocean: Jacques Piccard, Don Walsh, and James Cameron. And where the Moon has been visited by over one hundred spacecraft, the deepest part of the ocean has only had two probes. Though both places are incredibly interesting and deserve more exploration, it turns out that the ocean bottom poses a much larger challenge. Indeed, its deepest part is called the Challenger Deep (after the first ship to try to measure how deep it was).

The bathyscape ("deep capsule") Trieste at the ocean floor (Image courtesy the US Navy)

The bathyscaphe (“deep vessel”) Trieste at the ocean floor (Image courtesy the US Navy)

The reason that the ocean is more difficult to explore than space is because the ocean is full of water where space is full of nothing. In space, once you point your spacecraft in the right direction and give it a little push, the craft continues serenely on. In the ocean, you must constantly push against the friction of the water and the drag of the tides and the currents and the exigencies of plankton, nekton, and benthos. In space, the only poisons and corrosives are the ones that you bring with you. In the ocean, the very water you move through will rust away your vessel. And in space, you must worry about keeping one atmosphere of air in. In the ocean, you must worry about keeping 1,100 atmosphere of water out.

The ocean is a much more dangerous place than outer space.

The ocean is a much more dangerous place than outer space.

That last reason is the main reason that so few have visited the bottom of the Challenger Deep and have only stayed a short time. Under 1,100 atmospheres of pressure, things get crushed. A lot. The head of a styrofoam mannequin shrinks down to the size of a fist. All of the air in a room would fit into a breadbox. And even water itself, one of the least compressible substances known, shrinks so that there is an extra 1.4 tablespoons of water in a two liter bottle. The problem is that not everything shrinks the same amount or at the same time. As a result, an electrical connection that was snug at the surface becomes loose at depth, and a window that was sealed tightly on the deck of the support ship sprouts tiny, fire-hose like leaks on the ocean’s floor.

Spheres resist pressure because all parts are squeezed equally

Spheres resist pressure because all parts are squeezed equally

Despite this, we will continue to explore the ocean’s floor. Using pressure capsules that are shaped like spheres in order to resist the pressure and foam filled with spherical plastic beads for floatation, aquanauts will dive to the bottom of the ocean again and again. Though some may do it for fame or notoriety, most of the explorers will do it so that we can learn what is down there. Without pure research such as this, we would never have learned about black smokers or chemotrophs that live off of chemicals instead of sunshine.

If you’d like to help scientists learn more about critters that live in the deep, consider helping the folks at Digital Fishers classify fish in a reef:
http://digitalfishers.net/

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