4 November, 1995

November 4, 1995

Location: Latitude = 60 39í south Longitude = 54 11í west

Update: It has been a busy day on the ship today. After midnight, the OSU team made test number 8 of the zaps sled looking for hydrothermal vents. This morning Jay deployed a bottom ocean pressure gage which is used to measure changes in ocean currents and tides and a variety of other measurements. This device stays permanently on the ocean floor and has a battery life of about three years.

The remainder of the day has been spent deploying the new multi channel seismic streamer. The stream is a device which the scientists use to look at the construction of the layers of the upper crust of the earth below the ocean. The streamer is a series of special microphones called hydrophones. The hydrophones can detect sound waves which are reflected from the rocks making up the earthís crust. To produce the sound waves for the hydrophones to detect, the ship towes six air cannons which fire every twelve seconds. This sound pulse bounces off the different layers of the earth's crust at different times and the hydrophones detect the reflected sound. A computer collects the data and averages the data recorded by the hydrophones and this data is then printed as two dimensional map of the earthís crust.

For the streamer to work properly it must be towed behind the ship at a depth of 40 feet. This is not an easy task, because the total length of the streamer is 1200 meters. The University of Texas science team and the shipís marine technicians spent a little over 5 hours adding small pieces of lead to the entire 1200 meter length of the streamer. A total of 200 pounds of lead were added to the length of the streamer. This additional lead makes the streamer sink just slightly below the surface of the water. To get the streamer to tow at a depth of 40 feet below the surface they have to attach special devices called ìbirdsî. These attachments are like small gliders which fly the streamer in the water. The birds are pressure sensitive and have two wings like an airplane. The wings adjust up and down due to the pressure of the water leveling the position of the streamer to a near constant depth of 40 feet even in high seas.

What made this exciting is that while we were deploying the streamer the waves grew to about 12 feet, the winds picked up to 20 miles per hour and it started to snow. It is cold wet work, but it is essential if the streamer is going to work properly. Everything is checked and double checked for safety and to make sure everything is in proper working order. We should start test firing the guns sometime after midnight tonight. The final attachments will be made to the streamer around 11:00 pm. Everyone has their fingers crossed. This is the first time that this streamer has ever been used, and it is the first time that a streamer of this type has been used in Antarctic waters. A lot of people have a lot of concerns. The proof will come tomorrow when the computer is started, the air guns start firing and data begins coming in to the ship.

For the OSU science team it has been a day to review data, plan for future drops and to make corrections and repairs as needed to their equipment. They have been getting positive data from their initial lowering of the sled, and will be making many future lowering to pinpoint potential areas of hydrothermal vents.

Daily life on the ship is pretty constant. Meals continue to be a focal point of the day for people to get together. Everyone looks forward to getting email. The ship connects twice daily with satellite to send and receive email, once morning and once evening.

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