January 9, 2011
After two journeys to the bottom of the sea and back, a grim marine weather forecast–60-knot winds and 12- to 16-foot seas–for target deepwater drop sites forces the Medusa back to shore.
The Medusa, back on deck after its second and final descent of the expedition.
By EDIE WIDDER
We’ve been WOW: Waiting On Weather. So much of what we do at sea is dependent on the weather, or more specifically the sea state. We have three- to four-foot seas at the moment, which is smooth sailing by some standards, but too bumpy for submersible operations.
A submersible is fine strapped to the deck or tooling around beneath the waves. It’s just that transition through the air-water interface that’s the problem. That’s when things get dicey. A 6,000-pound sub dangling on the end of a cable on a rolling ship makes for a heck of a pendulum.
The same goes for big nets or Remotely-Operated Vehicles (ROVs), which together with subs are the primary tools available for studying life in the deep ocean.
I have often dreamed of a deep sea lab like the one in the movie The Abyss, where you can enter and exit through pressurized hatches the way they do in space. But in space, the pressure difference is only one atmosphere, about 44 pounds per square inch. That’s the weight of a five-gallon bucket filled with water. Imagine holding that on top of your head–not comfortable, but you could do it. The hatch on a spaceship must be able to withstand that force from the pressurized interior pressing outward toward space.
But now imagine you’re down in the ocean at 5,000 feet, the approximate depth of the Gulf oil spill. At that depth, we’re talking about the weight of more than 50 buckets of water–more than 2,200 pounds–per square inch pressing inward. That hatch would have to be a pretty amazing piece of engineering. The submersibles and ROVs we send to that depth must be carefully designed to withstand such enormous pressures without imploding.
The deep sea’s inaccessibility and its inhospitableness to humans aren’t the only challenges faced by those trying to study life there. There’s also the puzzle of how to study that life without disturbing it, or worse, scaring it away.
Edie Widder retrieves the Medusa’s camera bottle as Bryce Groark films.
Submersibles and ROVs have noisy thrusters and bright lights that can be highly disruptive. Camera systems left on the bottom are much quieter, but most still use bright lights that can literally blind deep sea dwellers that have sensitive eyes adapted for seeing the very dimmest of downwelling light or bioluminescence. These are the challenges that ORCA’s Medusa were designed to meet.
The Medusa is an unobtrusive camera system that uses far red light, which is invisible to most deep sea animals. It is a lander platform,which allows it to be deployed in much worse sea states than those required for submersible ops. Ultimately, the Medusa is a new tool for observing life in the deep sea,capable of being deployed to depths of 6,000 feet and recording unobtrusively for up to 60 hours–a perfect complement to the submersible operations planned for this mission.
The Medusa was supposed to make a series of deployments along a transect approaching the Deepwater Horizon spill site, while the submersible operated at shallower depths collecting video and sediment samples. But as today has worn on the weather forecasts have grown increasingly dire, with predictions of 60-knot winds and 12- to 16-foot seas. So we are no longer WOW–we are running for shelter! With only two surface-to-bottom-and-back deployments of the Medusa, we must abort the lander’s portion of the mission.
Edie Widder takes the Medusa’s camera bottle back to her makeshift shipboard lab, where she’ll download video shot while it was on the seafloor.
All of us on this expedition have spent a lot of time at sea, forcing us to become philosophical about such occurrences. A mission scrubbed because of bad weather is not a first for any of us, but it is still a tremendous disappointment.
These challenges of working on and in the ocean have made assessing the extent of the damage done by the Deepwater Horizon oil spill extremely difficult and have contributed to conflicting reports in the media. Our understanding of the complex web of life in the ocean is still limited by our all-too brief visits, which can be cut short at Neptune’s whim. We must continue to seek new and better ways to explore, monitor, and protect life on our ocean planet.
Support for the Mission Blue Gulf of Mexico expedition is provided by the National Geographic Society, Google Inc., the Waitt Institute, and Hope Spots LLC. Follow along in context by clicking on the ship icon near Pensacola, Florida using Google Earth.
Read all Mission Blue expedition coverage here.
Photos by Ford Cochran