FeMO2 Dive Cruise 2007
Report Day 10 -- Saturday 20 October 2007 -- Moon Mats and Tripods

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Ula Nui is 4 km deeper and 25 km from Pisces Peak. Jason had been recovered shortly after midnight from Pisces Peak and the ship transits to Ula Nui for our last dive there. Jason is ready to dive again at noon and is put into the water to begin its 5,000 meter descent to the bottom. This is dive 313.

Brian Glazer's precision tripod for detailed in situ

The precision tripod for the electrochemistry probe is on this dive. It's never been used successfully in water this deep and when deployed it is found that the tripod will not lower the probe. The probe is lowered on a threaded rod geared to a small motor. The gears seem to be locked. Later when pulling it apart Brian speculates that the extreme pressure at Ula Nui has distorted the gear housing slightly. There is very little clearance between the gear teeth and the housing so very little distortion would be required to jam it. The tripod is returned to Jason's basket and while attempting to secure it, a fitting is broken by one of Jason's manipulators. I'm reminded of Bob's comment that using a manipulator is like trying to write your name in the mirror with an arm full of Novocain.

After sampling at Ula Nui, Jason is directed to explore to the east. After crossing pillow basalts for several hundred meters a huge mat is discovered. It is covered by a black crust that appears to be mostly manganese oxide. The crusty mat has mounds 2 or 3 meters tall, and is pock marked with small craters. It reminds somebody of the surface of the moon and it is immediately named the "Moon Mat". It's possible the craters are vents, but no shimmering water is seen and no temperature anomaly can be found with the temperature probes. The Moon Mat appears to be hydrothermally dead.

The strange mat engenders a lot of speculation and armchair hypothesizing. Someone speculates that the Moon Mat may be a less developed version of the mats at Ula Nui. Perhaps the mounds form around vents like mud volcanoes. Later they coalesce to form a mat, and not until they die do they crust over. Another speculation is that the material under the crust is not biologic, but soft clay-like minerals. A further question is whether or not the craters are vents, collapse structures or even incurrent openings.

The location of the Moon Mat is recorded and left to future expeditions. Jason will not return here again this year. By 4 AM Jason is being brought back aboard and the ship begins a sonar survey of the area.

Shawn Doan onboard the R/V Kilo Moana
20 October, 2007

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