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.

Emboldened by the smoothness of glider calibration casts on the 5th and 6th of May and hurried by weather reports of a looming storm, we took advantage of the close proximity of the gliders to perform the remaining two glider calibrations back-to-back on the morning of 7 May. SG143's CTD calibration cast took place first, at a distance of ~200m from the glider and with SG143 spending a total of 18 minutes on the surface. It was a little tricky because 143 has been diving faster than the other gliders, and popped up after its medium-length set-up dive half an hour early -- during breakfast.

All four gliders are working well. We have just completed two calibration CTD casts on the R/V Knorr, one each between 9-10am local time (UTC) on the mornings of May 5th and 6th. We lucked out and got a bonus on the calibration cast for SG142: there's a tantalizing feature down at 300m that illustrates nicely the physical processes that contribute to the carbon pump.

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The floats parted ways during a storm on 17 Apr (UTC), and the gliders followed suit. SG141 and 143 have caught back up to Float 48, and if things go well tonight, we'll put them on some shallow dives to see if that helps them stay with the float better. Meanwhile, SG140 and 142 were being pushed south, away from both the floats and the other gliders. I sent them east in the hopes they would come across a current headed north, and luckily they found such a thing just past 22 W.

The gliders have had a rough time of it, sometimes seeing currents with velocities up to 56 cm/s trying to carry them away from the two floats. I've had them training up their Kalman filters for the past couple of days, which should help them correct for currents dynamically. SG143 is testing it out now.

On the plus side, the gliders have been covering as much as 15 km on a single dive! To put this in perspective, 4 km per dive is respectable and 12 km is "really putting the pedal to the metal."