Keck Expedition 2004
August 2, 2004 Day 4
Update for Monday, August 2, 2004 (by Debra Stakes)
Sunday night, August 1, there was activity in the science labs and on the back deck of the Western Flyer until late into the night. Andrew had the job of backing up the data from the first seismometer but his new big external drive began to act erratically so we could not entrust our precious data to it. On to plan B, using borrowed drives and backing up all the data to DVD. Andrew was still at it at 7:00 the next morning, looking bleary-eyed but very happy. His efforts paid off with the confirmation of a full 12 months of data including this seismogram of a small earthquake right on the Endeavour spreading axis. We paused briefly to celebrate our first success, but preparations for the next day’s work were paramount on our minds. Since Monday’s dive will be to the Endeavour Broadband site (KEBB), both the elevator and the Broadband loggers had to be readied during the night. The elevator has two types of acoustic beacons so that it can be tracked both in the water column and on the bottom. These beacons had to be connected and checked during the night before the dive by Ben and Mike. The RIN (remote instrument node) that goes into the elevator contains four glass spheres inside yellow “top hats”. Three of the spheres contain batteries—enough to power the logger and seismometer for a year. The fourth sphere contains the datalogger. There are two underwater mateable connectors, one to connect the broadband sensor to the datalogger and the second to allow the ROV to communicate with the system on the seafloor. The ROV uses this connection to initiate the system and set the GPS clock in situ. The elevator with the broadband RIN was deployed by 7 am (while Andrew was finishing up the data from the night before) and landed on the bottom 30 minutes later to await our arrival (elevator on bottom.jpg). The ROV was put into the water soon after the elevator deployment, to take on the task of changing out the existing broadband station. This trip will be the first time that the ROV Tiburon has been used to deal with the broadband systems and we hope that the lack of practice will not be a big problem.
The broadband recovery/installation is a tedious process requiring pilot skill and concentration. Our pilots make it look easy, but we understand the challenge we had given them. The ROV first went to the elevator, removed the replacement RIN and carried it 200 m to the instrument site. The replacement RIN was placed beside the used RIN to begin to move the sensor to the new logger system. First the ROV had to connect to the old logger and go through a shutdown routine that included verifying that the sensor was alive and collecting data after 12 months in the cold and dark. The sensor package was suspended so that its connector could be moved from the old to the new RIN. Finally the ROV connects to the new logger and spends the next hour for the re-initialization. During this time we were all amazed to watch an earthquake arrive in real time, with the waveforms snaking across the screen on Tony’s lap computer. Confident that the system was working properly, we carried the used RIN back to the elevator and began to reverse the process.
The RIN was placed into the elevator where the pilots deftly hooked it into place. A tag line with football-shaped floats was released at the top to make it easier to snag the elevator when it surfaces. As we watched, an acoustic signal was sent to the bottom, releasing the elevator from its anchor to carry the RIN with our broadband data back to the surface. The ROV rose to the surface more quickly, and was back on board before it was time to launch the small boat that would actually recover the elevator.
The elevator with our data was taking its time to appear in the graying afternoon. The decks were filled with anxious people searching the horizon. Suddenly, the sun broke through, the sky turned blue, the wind died down, the seas calmed and the elevator popped to the surface only a few 10’s of meters from the side of the ship. (Ben wants you to know that HE saw it first, but several others challenge that claim….) The small boat towed the elevator back to the stern of the Western Flyer to be lifted back on board by the A-Frame with Chief Mate Darrell Palmer cautioning the crew to move slowly so as not to spill the elevator contents back into the ocean. The successful recovery means more data to download and new loggers to rebuild to prepare for the next day.
The data logger sits for an hour in the lab while we wait impatiently for the glass sphere to warm up to prevent condensation in the hard drives. Three months of broadband data have been downloaded so far. Such a good day, but the weather is improving, and we don’t want to waste a minute of it. The ROV is immediately sent back down to the seafloor to change out another short period corehole seismometer. This one was near the most vigorously venting hydrothermal field on Endeavour, the site called KEMF (for Endeavour Main Field). The system successfully collected data for a year and we installed another system that we hope will do the same. Certainly not yet a routine operation but our confidence builds with every success. The image on the left is the old corehole seismometer that collected data at the KEMF site for 12 months while the image on the right is the new system being installed.
Captain of the Western Flyer Ian Young advised us that the next day or
so would have extraordinarily good weather. He suggested that we consider
another elevator operation. A
planning session with differing opinions on priorities followed with votes
cast with dots on a map. These two images show our planning session,
with Will, Doug and Andrew arguing over the priorities. The dots
on the map shows our targets with the yellow dot at the new broadband
site to be installed tomorrow.
So at 8 pm we are steaming to the east, to take advantage of the good weather and install a new broadband system in the Nootka Transform Zone. This will be the most complex ROV operation for the Tiburon group. The science team will be up half the night getting the hardware ready and the rest of us will be up early to help with the dive.