Two Bigelow researchers descend into the depths of the Pacific

Posted:  Thursday, January 8, 2015 - 4:00pm
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On Dec. 4, Dr. Beth Orcutt and Dr. Graham Shimmield left Costa Rica for a 14-hour journey into the Pacific Ocean to study the Dorado Outcrop, located near where two tectonic plates, the Cocos and the Caribbean, intersect.

After arriving, they went down over two miles in the manned submersible ship Alvin, accompanied by pilot Phil Forte. While Orcutt is a veteran, this was Shimmield's first trip to the ocean floor.

“I've been studying the ocean floor for 35 years, but this was my first chance to actually see it as a landscape,” Shimmield said.

The pressure at that depth is staggering, at 2.2 tons per square inch. The sphere containing passengers in Alvin is made of 3-inch thick titanium so it can withstand the force.

According to Orcutt, the Dorado Outcrop is very unusual. It is a thermal vent that is cooler in temperature than most other ones discovered, though still much warmer than the water around it. It is also unusual because they know where the water exiting is coming from; it is entering through an area close by known as Tangosed, which means “thirsty.”

This means that the water is traveling a small distance very quickly before emerging at much warmer temperatures. According to Shimmield, the temperature measured equaled 11.2 C, while the surrounding water measured only 1.8 C.

“It is very unusual to know where the water is both entering and exiting,” Orcutt said.

The dive's objective was to collect samples that were as pure as possible from the warm water exiting the outcrop, so scientists could study how the water had changed.

“It helps us learn how to mine heat out of the earth, how the chemicals in the rocks affect the water, how the life is using them; it goes on,” Orcutt said.

Going down in Alvin is a unique experience, one very few scientists have experienced.

Currently, only five countries currently are doing manned seafloor expeditions: the United States, Japan, China, France and Russia. The majority of expeditions, mostly due to the danger, are done by unmanned robots.

“The descent takes about two hours,” Shimmield said. “Within the first 10 minutes all light filtering down from the sun vanishes. But there is a lot of bioluminescence on the way down, so we could still observe on the way down. It was slow and serene.”

“It also gets colder the deeper you go,” Orcutt said. “Leaving Costa Rica it's really warm, you carry a pillowcase on board with warm gear and the deeper you go the more you're wearing.” Since Alvin runs on battery power that needs to be conserved, there is no heating system on board for passengers.

Alvin spent five hours on the seafloor, which Shimmield said passed “way too fast.” The group saw many creatures including crabs, tiny shrimp and fish. The highlight of the living creatures were what Shimmield referred to as the “octopus spa.”

There were colonies of octopi clutching the rocks near the thermal vents, enjoying the warmer water they were ejecting. They also seemed highly interested in the scientific equipment the scientists were trying to use.

“The pilot was taking a sample, and suddenly this tentacle appears and nudges the syringe aside and pokes into the aperture were were using. It's like it was saying 'mine,'” Shimmield said.

When it was time to reascend, Alvin dropped the steel plates that gave it weight to sink and started back up.

“People often think there is a tether that connects us to the boat at the surface,” Orcutt said. “Nope — we're on our own down there.”

After appearing on the surface, they are retrieved by the boat. Until they are, they deal with what Orcutt called the “washing machine” effect as they bob around and roll back and forth.

Despite the cold, the wet (in the cold air the breath of the passengers condenses and drips on everything) and the cramped conditions, and it was still “the experience of a lifetime,” according to Shimmield. Orcutt agrees it is a wonderful experience and enjoys every descent.

Their adventure ending with the traditional initiation of an Alvin newbie being performed on Shimmield — a drenching on deck with six buckets of icy sea water.