Sunday 27th November
A very busy first day; in lieu of carefully crafted prose, here are some of the entries from our Science Log (although times shown here are ship's time, GMT plus 4 hours):
04:47 Arrived Dragon Vent field, 37 deg 47.027' S, 49 deg 39.000' W, water depth 2777 m.
05:00 CTD probe launched (25 seconds behind schedule!), measuring the speed of sound through the water between the ship and the seabed, to calibrate the acoustic navigation system for our underwater vehicles.
05:50 CTD data show the "plume" of smoky water rising from the vents on the seafloor below us.
Data from the CTD probe
06:00 Beautiful sunrise outside, with clear skies and calm seas. Great weather for ROV diving.
07:16 CTD back on deck; officer of the watch on the bridge manoeuvring ship into position to launch the ROV.
07:31 Ship in position for ROV launch. ROV team on aft deck prepping vehicle for dive.
07:45 Leighton has programmed data from the CTD probe into the acoustic navigation system that the ROV will use.
08:00 Final inspection of ROV setup for the dive by Jon and Leigh with the ROV team. All data recording systems in the ship's main lab, receiving feeds from the ROV, are up and running.
08:28 Deck crew report to aft deck to begin ROV launch.
08:44 ROV launched.
08:52 All surface checks completed; ROV begins descent.
Dragon Vent Field: 120 m behind us, but 2740 m below us
10:03 ROV arrives at seabed, depth 2840 m. Beginning transect NE into vent field after completing trim and tether checks. Sector-scanning sonar shows possible chimney targets ahead.
10:21 We have arrived at a huge sulfide pinnacle, >20 m high. Surveying the marine life on its sides. Some signs of "shimmering water" diffuse hydrothermal flow here, but this chimney appears to be "extinct", with no "black smoker" activity.
11:03 Pushing further into the vent field, heading to Waypoint 3 in our dive plan, checking out targets as they appear on our scanning sonar.
11:25 Arrived at another large vent chimney with a wide "caldron-like" structure at its top. Can see wispy black smoke venting from "beehive diffuser" structures on its side. Teeming with life.
11:52 Setting down ROV on ledge to collect specimens of marine life here, using manipulator arm, suction sampler, and nets.
In the ROV control centre
12:22 Suction sampler losing hydraulic pressure; need to conserve it for further sampling.
13:20 Starting close-up high-definition video mapping of one side of the vent structure, to measure the distributions of species at these vents.
14:05 Completed video mapping. Now investigating and sampling new patches of marine life revealed during that survey task, to ensure we have representative samples of the species here.
14:57 Continuing a sweep back to the west, to join up with our initial dive track surveying the vent field.
15:30 One hour of bottom time remaining.
15:50 At large sulfide structure; platform at top is "extinct", but actively-venting flange on its side. Recognising the structure as one visited earlier at the start of our dive, so our survey line is now closed off.
16:32 Leaving seafloor.
16:36 Encountering thick "smoke" in water column from active vents somewhere below, but cannot return to seabed on this dive. Target noted for HyBIS dive tonight.
17:45 ROV back on deck.
18:00 Science team transferring samples from the ROV into the Controlled Temperature Laboratory, for triage. Processing samples takes until 23:15h
18:35 HyBIS vehicle launched for further exploration of the vent field overnight.
19:28 HyBIS recovered to correct camera malfunction.
20:02 onwards: Veit and James continue to survey the vent field through the night with the HyBIS vehicle, in search of the source of the "big smoke" seen during the initial ascent of the ROV from the seafloor.