August 10 - August 17, 2006
August 12, 2006
Second ROV Dive: First Use of PUP
Today, the Brewer Lab Group’s main objective was to use PUP (Precision Underwater Positioner) to focus the standoff optic laser of DORISS on exposed methane hydrates along the ridge. This was not a particularly easy task, as yellow-tinged, bacteria-generated oils covered a large percentage of the hydrates, causing florescence and washing out the much weaker Raman signal. In addition, the highly variable topography of the canyon outcrops made finding stable positions for the ROV to land time-consuming and difficult.We did have considerable success today, however, as we were able to detect the hydrate gas (i.e. methane) signal with repeated exposures in quick succession. This marks the first time methane hydrates were chemically analyzed in situ in their natural formations on the sea floor.
The rest of the day was spent on multiple attempts with various techniques to obtain coring samples, including the use of heating probes and a serrated knife. While the coring tool was ultimately successful in removing the hydrate from the mound into the coring tube, extracting the sample from the coring tube itself proved incredibly difficult given the equipment setup at the time. Tomorrow’s experiment will use a hydraulic ram to push out the core, despite its inherent decreases in drilling efficiency.