Transcript for Oceanfloor Legacy, segment 06 of 14


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The sea floor mapping begins after launching an imaging instrument called a side-scan sonar towfish. The towfish sends out a sound pulse over a wide swath of the sea floor. These sound waves bounce off the bottom and are received back by the instrument. That sound energy is then relayed to a shipboard computer where the data are processed and printed out as strips representing the sea floor.

We've started up the program over the last year or year and a half dealing with the side-scan data, and being able to go to sea, collect it, and actually present it in this form at sea, which is a fairly new thing - before it used to be that people would take the records back to the lab, look at them on big sheets of paper that they were recorded on, and make their interpretations, but that was about the extent of it. To have a big picture like this is really something new and exciting.

In the mapping the reason we're running these, what would appear to be very monotonous tracks back and forth is the same thing you would do every day if you mow your lawn, and that's basically it. It's just to cover the sea floor. We have to make sure that there's overlap with at least one of the look directions so that we can within - we actually can build our picture of the sea floor. The trick is, is one of the things that we've been developing here is that we can take and process this data in somewhat real time. We call it pseudo-real time. It doesn't happen immediately, but we can take the image and take the geometric distortions, merge it with navigation, and create what would be a true picture or a true sonograph of the sea floor aAnd then actually start building the mosaic at sea, and this also allows us to do what we're doing on this cruise - build a picture, turn right around, and sample on it.

Over the two week survey leg the geologists gather data for four separate mosaics, including one of the main research area and three high-resolution mosaics of existing dump sites.

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