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MISSION DISPATCH 6 August 25, 2005 | Brian Cousin - @SEA Correspondent Today's venture into the sea did not start well. During the final pre-launch check of submersible systems, an inverter in the main power distribution can stopped functioning. The dive team, already sealed in, disembarked and the sub crew began tracking down the source of the problem. Ironically, it was traced to a switch in the emergency power panel inside the sphere. When the switch is in its secured position, power is supplied to all the submersible's exterior systems - lights and the manipulator arm, for example. In the event of a real emergency, manually throwing the switch prevents power being distributed to those types of systems and accessories, reserving it all for essential life support systems inside the sphere and aft observation chamber. 
Manipulating the switch restored its proper function. Submersible Ops Coordinator Craig Caddigan deemed the system safe for diving and the pilot, technician and science crew loaded up again. Normal launch procedures began, and the ship's massive A-frame lifted the JOHNSON-SEA-LINK I (JSL) off the deck and boomed it out over the stern. Every safety-related issue regarding operation of the R/V Seward Johnson and submersible at sea is taken very seriously. The safety of the crew takes precedence over any other operation, including the recovery of scientific packages deployed on the bottom. Everyone is encouraged and trusted to raise concerns that could affect their safety and the safety of others on board. So it was without hesitation that the submersible was boomed back in from the launch position when sub tech Jimmy Nelson reported unusual sounds around the sub as it was being boomed out. 
During the process, the winch that tows the sub up behind the ship during an actual recovery lost hydraulic power - not too bad a problem with the sub on deck, but had the sub been in the water a simple recovery would become a challenging proposition. Under normal conditions, the winch maintains tension on the towline, wrapping it around the drum to take up the slack as the sub is boomed aboard. This morning, the towline lay in a pile on the deck, and half a dozen crewmembers pushed on the sub to accomplish what the winch could not. The ship's crew is looking for a way to fix the winch, but if parts are needed and not on board, we could be face a trip to shore to get them. Dr. Tammy Frank and Dr. Edie Widder may face a longer than anticipated delay in the recovery of their benthic traps and Eye-in-the-Sea (EITS) camera system . 
The scuba divers made their third blue-water dive of the mission. Dr.
Mike Matz took an underwater spectrometer to make light readings at
various depths. It's a neat little unit that Dr.
Justin Marshall had a
hand in modifying for underwater use. A custom housing was designed to
accommodate the compact package including spectrometer, battery and
Personal Digital Assistant (PDA) to control it. Mike says it's difficult to
model how light appears in the ocean. "We want to understand how the
environment is perceived by its inhabitants. There are dramatically
different optical qualities that require measurements and even
imagination perhaps, to make sense of them. For example particular colors,
UV, or the bioluminescence that Edie studies. The best way to measure is to
go there." Mike has made measurements on sargassum animals collected on
this mission. "Sargassum shrimp fluoresce. Sargassum fish don't. How are
these animals' eyes adapted to their environment? To find out you must
understand their environment - the background color, the color of the
substrate, sargassum in this instance." Tammy Frank's post doc, Dr. Jon
Cohen, has made measurements of the sargassum shrimp's visual sensitivity
to help understand how they perceive their world.
For the dive, Dr. Justin Marshall traded his video camera with ultra violet filter for a digital still camera that accepts the same UV filter in front of the lens. One of Justin's areas of study is the possibility that UV sensitivity in the eyes of some animals may make other animals more conspicuous in the water. Under polarized light, some animals that normally appear perfectly transparent are betrayed by structures in their physiology, such as muscle bands. UV sensitivity could behave in a similar way. He returns with photographic data for his studies as well as some wonderful photographs of little microcosms of fish busily congregating around larger jellies, all adrift in the vastness of the ocean. A rainstorm reaches our location, and from our working depth at about 40 feet we can look up to see raindrops splashing the surface. The shower passes as the divers continue to work. After the dive, the sun is shining again. We radio the R/V Seward Johnson to report that divers and equipment are safely aboard the small boat and discover that repairs are still being made to the submersible's tow winch. Since there's no hurry to return to the ship, we take the opportunity to snorkel around the small boat, collecting a few more samples and enjoying the opportunity to be in the water. 
Back onboard the R/V Seward Johnson, repair work continues on the tow winch until a thunderstorm sends everyone looking for shelter inside the vessel. Mechanics of the problem have been identified and the crew are persistent in their efforts to locate and correct it. All of us onboard are following reports on Tropical Storm Katrina, expected to hit Florida's southeast coast later today or early tomorrow. Many of us have homes and families in the risk area and we are thinking of them. Katrina could become a Category 1 hurricane before hitting the coastline with winds above 74 miles per hour and flooding rain. Next, the storm is expected to head into the Gulf, possibly towards our position. Chief scientist Tammy Frank provides an update on our situation. We are transiting to Port Fourchon, Louisiana to await parts to repair the winch. We may move to Gulfport, Mississippi if Katrina's storm track allows, because it puts us closer to Vioska Knoll where we must return to pick up the Eye-in-the-Sea and the traps. It's a favorable location and we will likely stay for several days. In any event, we must wait until Tropical Storm Katrina's effects are gone, and it's safe to go back in the water. 
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