April 30th, 2003; Leg 5, Day #10

Last night, ROV Tiburon's manipulator arm failed the in-water checks, and the decision was made to switch to an older, spare manipulator. In part because the spare arm is more difficult to use with its old-style control, or "master," the pilots resisted making the change until there was no other option. They worked on Tiburon until nearly midnight when unfortunately another problem occurred—this time with the main computer system. This kept them busy through lunch, and it wasn't clear whether we would dive at all today. Their incredible skill and hard work resulted in success by mid-afternoon, and Tiburon was put in the water for the final dive of the week. The goal was for the laser Raman spectrometer (LRS) to measure a sample of natural gas hydrate collected from the seafloor. 

ROV Tiburon gets ready to dive.
Is that Pinkie looking on to wish
us luck?

“’Pinkie’s” silhouette guided us to the gas vent. Once there, the LRS system was turned on and readied for measurements. The pilots first tried to use a push core to collect a hydrate sample, but the mud was so sticky, they couldn't empty the tube. The scientists noted the irony in this, as it is not uncommon for a push core sample to fall out of the tube when it is transferred to the drawer. Next the pilots tried a hoe-like tool to scrape the seafloor. Chunks of hydrate were liberated from the sediment and began floating upward. Several attempts were made to catch this rising material with a funnel. In the end, the funnel itself was scraped along the bottom and some hydrate was trapped. The manipulator arm brought the sample over to the LRS stand and the measurements began. 

Unfortunately, it appeared that something was wrong with the LRS. Sheri White and Bill Kirkwood saw that the spectral sensitivity had greatly diminished. They also noticed that the focus motor was not working properly, which was necessary for these measurements. The LRS system was powered off, and this part of the dive was finished. The science team soon decided that Tiburon should be recovered, as was nearly time for the dive to end anyway so that the R/V Western Flyer could begin its transit back to La Paz. 

The ship is underway now and should reach La Paz by mid-afternoon tomorrow. 

– Debbie Meyer

Bill Ussler analyzes a sample under the microscope.