The final NAB08 cruise on the R/V Bjarni Saemundsson departed Reykjavik the morning of 25 June with Mary Jane Perry as Chief Scientist and Keith Van Thiel as the glider ‘guy’, Kristinn Gundmundsson for primary productivity measurements, Katja Fennel (now a sea-going modeler) and Lindsay Dinsmore for water sampling. Very unlike the deployment cruise in early April, this trip sailed on relatively smooth seas.

SG141 received a final calibration CTD cast before its recovery on 27 June, confirmed aboard the R/V Saemundsson at 14:51 UTC. SG140 received its final calibration CTD cast and was recovered on 28 June, by 14:45 UTC. SG142 is presumed lost.

The science team on the Saemundsson will do more CTDs during their cruise, and are additionally acting as a vessel of opportunity, launching a few floats in the area for a French research project.

Around 25 June @ 22:30 PDT, the field team called in to say that they had finished the NE arm of the search grid and had reached the center of the bowtie, with nary a peep from SG142. They called again on 26 June @ 12:00 PDT to report that they had proceeded through the NW arm and continued to the southern half of the search grid -- and still no sign of the glider. They will finish up the search grid by nightfall, and then (assuming there's no reply from SG142) they will abandon the search.

Seaglider 142 made its last call home on 24 June 01:34 (UTC). So far, there is nothing in the logs to suggest that something was going wrong. It is a mystery that will hopefully be solved by finding the glider via accoustic tracking.

The shore-side crew have identified the 4 possible scenarios that are most likely:

1) It's stuck on the bottom. It could be snagged on something, or it might have suffered a VBD failure. (The VBD, or "Variable Buoyancy Device" is the rubber balloon outside the pressure hull that can be filled with oil to change the glider's buoyancy.)

While SG143 was recovered on 3 June 2008, shortly after Float 48, the remaining three Seagliders began a new survey pattern on the eastern flank of the Reykjanes ridge:

SG140 is executing a large bowtie pattern, and SGs 141 and 142 are repeating a 20-km bowtie: sg141 performing north-south transects on the sides of the bowtie, sg142 performing east-west transects and drawing an hourglass.

Over two months into the experiment, and three gliders continue operating out of the initial 6 platforms. The Bjarni Saemundsson rescued one float and one glider. The remaining gliders will continue executing a fixed repeat pattern through June.

It was a very smooth recovery -- we were getting good RDF fixes for about 20 minutes when Mary Jane spotted it. We took pictures of the various sensors and the float itself before washing it down. There was some biological growth, primarily brown slime, but it came off very quickly and easily. The Licor's bracket was extremely fragile and broke once on board, as with float 47.

We're set to go on the rescue cruise on the R/V Bjarni Saemundsoon, leaving this evening from Reykjavik at 20:30 (or so). Mary Jane Perry is the Chief Scientist, Mike Ohmart is the Float guy, and I'm the Glider 'guy'.

Magnus (an assistant from the Icleandic Marine Research Institute) put Mary Jane's optics instruments on the CTD this morning, while Mike and I prepared float 47 for shipping. The float is much like the glider, in that it's designed so you only need two people to move it around and take it apart.

I now believe that Float 48 is now in a stable state on the surface, sending ARGOS fixes and awaiting recovery. We should be able to recover it using the RDF, just like we did 47.

The float started showing file system errors earlier today. These progressed and after 10 write errors, it aborted the mission, blew the bolt (we think) and tried to start the recovery mode program. However, the program load didn't succeed probably because the file system is crashed leaving only the backup ARGOS location system.

The lessons are the usual ones:

After 50 days operating, the second float and one glider have malfunctioned, leaving three operating gliders. The Knorr finished a successful cruise this week and discharged the science crew in Iceland.

A rescue cruise on the Bjarni Saemundsson is being organized for the errant platforms. For approximately the next month, we will operate the gliders alone in a coordinated pattern. They will be recovered in July on a final Saemundsson cruise.