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Meridian Passages, Volume XIII, Number 15

Central Pacific Edition

Thanks to hard work and good performance by REMUS OPS, we are being treated to some amazing imagery from the bottom of the ocean. A particularly dramatic example of what is probably an undersea landslide is shown here. Several sonar passes were made over this area with each swath overlapping. After the REMUS collected the data, Jeff merged it together with navigation to make a mosaic, yielding the composite image shown here.

undersea-landslideTo get an idea of the scale of this feature, the spacing between the light stripes running across the scene is 1,100 meters (0.6 nm). That makes the pile of rubble at the top of the screen about a half mile across. The stripes represent the nadir of the sonar (line directly below) where imagery is poor. We overlap swaths to be sure to cover everything.

As interesting as this terrain is, we are hoping to avoid a lot of rough bottom, as crevices and craters can hide our target. Also, steep ridges can be a hazard for the AUV as we try to skim the sonar just off the bottom. However, we must take what the sea will give us, and these topographic features are not only interesting, but provide some geographic “tie points” to help us assess our navigation accuracy and to ensure we line up with older data. Fortunately, the vast majority of the seafloor in this region is quite flat and featureless, and the Electra should stand out clearly when we image it.

Operations Summary

Mission 007 concluded yesterday morning and Mission 008 started after a swift turnaround. Two notable improvements were achieved. The battery pack service life was extended to permit more lane coverage per mission, meaning more survey time available. And the on deck service interval was reduced by a significant amount, meaning more survey time available. All of this speaks well for the teamwork that is evident out here. Well done everyone!

S/V Sauvage Arrival Imminent:

The meeting at sea of the sailing vessel Sauvage and Mermaid Vigilance is planned for Sunday. A personnel transfer by small boat will occur in which explorer Alan Eustace will join the team and participate in the mission for a number of days. Alan has come all the way from California to be with us. Be sure to welcome him aboard.

We’ll also host a visitor, Nino Wattrelot, crewmember of Sauvage and licensed engineer in the megayacht industry. He asked for a tour of the Mermaid and to have a look at the technology we use. A lifelong sailor, Nino was raised on sailing yachts. He has traveled extensively around the Pacific. You are encouraged to chat with Nino – just remember security at all times, “You are not free to discuss details of the operation.”

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