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Yesterday, we completed CTD operations and then proceeded south in open water until we encountered pack ice at approximately latitude 65S. We pushed into the pack ice and made good progress in the late afternoon, pausing only to do Trace Metal CTD trials.
The RMT (Rectangular Midwater Trawl) was assembled on the trawl deck during the evening as we passed through the pack. A light dusting of snow fell as we completed this task about 10pm ships time.
Overnight the ship encountered heavier ice conditions causing a slight deviation to the west but we eventually reached the open water (or Polynya) this morning just to the east of Drygalski Island. We had intended to conduct targeted trawls on any acoustic signatures (a.k.a. “blobs on the echo-sounder”) observed during the transit but nothing suitable was seen.
At 10am, it was decided to conduct a trial RMT shot to test the equipment and at 0430UTC, a historic moment in the Australian Antarctic Science program took place when, for the first time on the Aurora Australis, we were able to receive live high definition video footage from 2 cameras mounted on the trawl net at a depth of 200m. The images were transmitted back to the ship along a tow cable consisting of optical fibres and power conductors encased in a steel sheaf and which is capable of towing payloads up to several tonnes. This tow cable, which is 5000m in length was purchased about 3 years ago and it has taken a really major effort by AAD Science Technical Support staff to turn this purchase into a working system that can be successfully deployed in Antarctic waters.
A large crowd gathered in the instrument room to watch the first deployment and the system instantly showed its value by revealing that the net release mechanism was stuck, meaning that the net had not actually opened when commanded to do so.
Upon observing this problem on the screen, our Senior Krill Hunter, Rob, was able to make an innovative suggestion to the winch operator which resulted in the net opening correctly. It was an immediate illustration of the value in having live video feed to surface during operations. Without the cameras, we would have completed the trawl with the net closed and wasted valuable ship and science time.
We even caught some krill which are now swimming around in the krill tank on board.
It’s been a big morning. We are now returning northwards with the intention of conducting more CTDs this afternoon.
Lloyd and Brett
Map
A map showing Australia and Antarctica. The map shows the journey of one voyage that has occured in the season, with each route highlighted in a distinct colour.