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MISSION DISPATCH 10 September 01, 2005 | Brian Cousin - @SEA Correspondent 
We're back in business. After about 36 hours transit, the ship is back
on station at Vioska Knoll. A test launch of the
JOHNSON-SEA-LINK I (JSL)
to verify operation of the tow winch went without a hitch, and the sub was boomed
back in to collect its payload of scientists and their equipment.
There are multiple objectives for this dive. Engineer Lee Frey is in the sphere with pilot Tim Askew, Jr. He'll use the LoLAR 2 (Low Light Autocalibrating Radiometer) to generate a down-welling light profile at five depths during the descent. Dr. Edie Widder is in the aft compartment with her spectrometer. Submersible technician Jimmy Nelson is also squeezed into the small compartment. Dr. Tammy Frank placed two of her benthic traps in the sub's front collection basket to be deployed when the sub reaches bottom. Two pieces of unfinished business fill out the agenda - find and collect Tammy's benthic traps and Edie's Eye-in-the-Sea (EITS) camera that were left on the bottom seven days ago. The double trouble of hurricane Katrina and the ship's defective tow winch caused us to leave the area without them. 
The sub is making slow progress along the bottom. Visibility is limited to only about 12 feet due to the bottom being churned up by the hurricane and the sub's lights can't help. To make Edie and Lee's light measurements on the way down, all the submersibles lights had to be turned off. Once in the chill of the deep water, the penetrating arc light will not fire. To recover Tammy's traps without blinding any captured animals, the two powerful HMI lights are covered with filters, correcting their normal bright white to dim red and orange. In these conditions, spotting the Eye-in-the-Sea won't be easy. In time, Tim Jr. reports to the surface that the camera has been found. Maybe just by pure luck, the bait bag containing the sonar Tammy deployed with her traps had moved about 50 feet, closer to the EITS. The EITS was found tipped over on its side - there is speculation about the cause. The most likely scenario is believed to be that some large predator knocked it over wrestling with the bait strapped onto the frame. The blue-water scuba team took to the water after the sub came up, to make collections of zooplankton and video recordings of polarized light. Though the water appeared a little greener from the surface, none of us predicted the low visibility we found below the waves. Particulate in the upper ten feet cut visibility to about ten feet. Below ten feet, visibility improved to about twenty feet, so for safety we shortened our tethers to remain in sight of the safety diver. Dr. Sonke Johnson and his post-doc Dan Speiser managed to catch some good samples of gelatinous zooplankton, but Dr. Justin Marshall was unable to shoot polarizing light due to the poor conditions. Seven days earlier at this location, visibility in the clear blue water was over of 100 feet. Dr. Mike Matz, the fifth blue-water diver was scheduled to be in the submersible for its second dive of the day, and therefore prohibited from scuba diving as a safety precaution. 
Erika Raymond is in the midst of downloading EITS' cache of data, watching as each 1-minute segment plays on her laptop computer. Suddenly she cries out, as a number of sharks swim through the frame and go for the bait attached to the Eye. Soon the entire science crew is gathered around to watch the scene, and hangs on in anticipation of what the Eye might reveal next. The sub goes down again this evening with Mike Matz in the sphere with Tim Askew, Jr. Edie was uncertain about deploying the Eye-in-the-Sea again because we are not receiving the detailed weather data we use to determine sea states days in advance. These data came to the ship from a location in New Orleans that is no longer transmitting. Finally, Erika and Lee get her to capitulate, and the Eye is readied for this evening's JSL dive. In addition to deploying the EITS, the sub will deploy two more of Dr. Tammy Frank's benthic traps and pick up the two that were left on the bottom this morning. The Plan C iteration of traps will be refined. Under Plan D, the ends of the traps will be fastened just inside instead of on the outside, to allow the Bio Boxes to close fully when the traps are deposited. Tolerances are exacting, and modifications proceed on a trial and error basis. SECOND GENERATION LoLAR Harbor Branch Engineer Lee Frey describes the LoLAR (Low Light Autocalibrating Radiometer) Generation 2 as a very sensitive light measurement instrument. "There isn't another sensor anywhere with the dynamic range of LoLAR 2. It is able to measure anything from direct sunlight to the slightest bioluminescent flash of a deep-sea animal." A number of Harbor Branch engineers, electronics experts and machinists had a hand in developing LoLAR 2 with Dr. Edie Widder, who uses the sensor. "Larry Taylor, Brian Ramos and Dan Boggess were the key hardware and software people - it's their instrument", says Lee. It's completely different from the first LoLAR, developed by Edie and Harbor Branch engineers in the early nineties. Edie says, "The old LoLAR needed a lot of updating. It was old technology and the software was hard for other people to use. I wrote a proposal to NSF for a redesign and it was funded on the first try. Lots of publications came out of LoLAR 1, so it was a very useful instrument." 
LoLAR 2 is still a sensor for recording the irradiance of light, but features a number of improvements. It has more dynamic range to measure brighter and dimmer light, as well as more wavelengths, thanks to a special spectral filter wheel. A tilt sensor indicates true gravity referenced top-to-bottom orientation. LoLAR 2 has a CTD sensor for measuring conductivity (salinity), temperature and depth of the seawater and a PAR (Photosynthetic Available Radiation) sensor - another less sensitive type of radiometer, all mounted on a pan-and-tilt head. The electronics and software were redesigned for simple Ethernet communication. Lee designed the user- friendly interface for the system that can be run on any Windows computer equipped with a small software package. Intentions are to include it with other scientific equipment packages that can be monitored from a number of sites in a Local Area Network. One of the unusual developments for LoLAR 2 is a triggered mode that can observe the deep-sea bioluminescent phenomenon known as 'flashback'. Flashback occurs when the sub sits in total darkness for a short period and then very briefly flashes its lights on and off again. A startling return flash of bioluminescence sometimes appears in the water outside the sub. One sub pilot tells of creating a pattern through the sphere with a flashlight that was 'mimicked' outside the sub. In triggered mode, LoLAR 2 will wait at its most sensitive setting with its shutter closed. The PAR sensor attached to the LoLAR acts as the trigger, sensing when the subs lights are flashed on and off. When the light reaches the low threshold, it will trigger the LoLAR's shutter to open and record any returned bioluminescent 'flashback'. Lee says he's impressed with LoLAR 2. "The first time it got wet was on the first dive of this Deep Scope mission and we got useable data - that doesn't happen all the time". 
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