Saturday, May 31, 2014

Research Cruise UPDATE: Another successful day...

A successful core from NT800.
After completing our work at NT800, we move about 6 km to NT1000. This is a site at a depth of 1000m on a somewhat steeper portion of the slope. There was some concern about sampling this site because on the previous research cruise at this site in September 2013, the team made lowering after lowering with the multicore here, but failed to collect any samples. There was concern that this site was unlucky, but perhaps because of the reduced weight on the core, all three lowering succeeded perfectly. The cores were short because the bottom is pretty hard here, but the mud team pronounced themselves contented and we continued our work with a MILET survey. 

The MILET is an instrument platform operated from the surface over a fiber optic cable. Mounted to the platform are video and still cameras, a subbottom profiler, and navigation pingers that report its position while data is transmitted to the surface in real-time. We use the MILET to survey the mobile fauna and record subbottom features for the geologic record. A typical MILET survey lasts about four hours on the bottom and records data on long transects that criss-cross the sampling location. Two and one half hours into the survey at NT1000, we lost fiber optic communications with MILET due to a faulty connector. 

Weatherbird II then proceeded to the S42 sampling site. Seas were choppy with heavy local rain squalls. Completed a CTD profile before beginning with the multicore We had a failed multicore on the first lowering. The VTLC showed another pre-trip in the water column, so the winch operator and helmsman adjusted the speed of lowering and put the ship in the trough to reduce pitch. All three subsequent lowerings were successful. Repairs of the MILET are still underway, so WB2 got underway toward S35 in the early hours of 1 June. 
Ben LaBelle, Nikki Morgan, and Curtis Okolovitch sieving cores late at night
Multicore frame showing two additions—cylinder on left is a
USBL navigation pinger that provides bottom fixes for all cores,
cylinder on right is the video time-lapse camera that
records core collection and bottom type.

 Posted by:

Ian MacDonald
Florida State University

No comments:

Post a Comment