April 29

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April 29th, 2003; Leg 5, Day #9

It is 7:30 p.m. local time, and the pilots are finishing repairs on ROV Tiburon's manipulator arm in preparation for another dive. It has been a day of mechanical challenges with the manipulator. Two dives were already attempted today but had to be aborted when the arm wasn't working properly. The pilots worked all afternoon and through dinner to fix it. Tiburon has just been dunked in the moonpool as part of the checkout before the dive. If it passes these tests, the dive will begin. The dive will be short: an hour descent to the seafloor, an hour of measurements with the laser Raman spectrometer (LRS), and an hour to return.

Sheri White and Bill Kirkwood (at left with Peter Brewer) reconfigured the LRS system for today. Yesterday the sampling lens, or optic, in the system was an immersion probe, a metal tube with a lens behind a sapphire window that penetrated through the pressure housing. Today's configuration uses a non-contact optic that sits behind a dome window and can be focused on the sample. The LRS has been put into a stand that was attached to the "front porch" area in front of Tiburon's cameras (see below). Once at the gas vent, the stand will be placed on the seafloor. Tiburon will dig out pieces of the solid hydrate that form in the sediment. The funnel will hold the hydrate sample in place beneath the probe head, and the spectra will be measured.

If all goes well tonight, we'll do a full day of diving tomorrow. The pilots are making heroic efforts to keep Tiburon going until we return to La Paz on Thursday where a delivery of critical parts is waiting for them for the next leg.

� Debbie Meyer

The LRS system and stand attached
to ROV Tiburon's "front porch."

Unfortunately, the manipulator arm failed the in-water tests this evening. The pilots have determined that it can't be fixed for this leg and have decided to install an older, different arm. They have a long evening ahead of them to get everything working by tomorrow.

These small bivalves were collected immediately surrounding the vent. The rock, collected not far away, contains fossils of what appear to be the same species. These samples illustrate the processes going on around the seep and are being interpreted by the science team.

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