The first SWAIS2C field season at the KIS-3 drill site on the Ross Ice Shelf is over, and our on-ice team is heading home with some cool new data and invaluable on-site experience as we continue our efforts to recover long sediment cores at our two study locations.
Twelve scientists, 10 drillers, and 4 camp staff deployed to the KIS-3 site in late November through early December 2023 and set up an efficient camp comprising many sleeping tents, a mess tent, three science facilities (tents and container), and a large drilling tent.
Hot water drilling through ~580 m of ice went exceptionally well, and we broke through the base of the ice shelf into the ocean cavity just before Christmas. Our first science activities through the open hole began immediately. Over a twelve-hour period we were able to collect several sediment cores using a gravity corer, acquire oceanographic data during several CTD casts, and collect video camera footage from the seafloor and the bottom of the ice shelf.
Gavin Dunbar holding the longest core ever sourced from the Siple Coast
On December 23rd, the Antarctic Intermediate Depth Drill (AIDD) was moved into place. Our drillers had deployed ~80 m of drill string, including the heavy steel bottom hole assembly and many lengths of sea riser made of glass reinforced epoxy, when we had to halt operations due to technical challenges. After careful consideration of all options and risks involved, our leadership team decided to end drilling operations for the season. Our drillers were able to safely retrieve all drill string, and we have very clear options to modify our operations to mitigate the technical challenges we experienced this year.
Once the ice shelf hole was clear of drill pipe, we started another phase of open hole science activity. These included additional gravity coring and a series of continuous CTD casts over a 24-hour period.
On December 28th, we deployed a hammer corer and recovered a 1.92-m long core, a record for the Siple Coast. This success was due to several innovative modifications to the core catcher and our deployment technique that were suggested and implemented by members of our drilling team.
We finished our borehole science operations with a successful deployment of an oceanographic mooring that will collect important data from the ice shelf cavity over years to come. These new data add to a sparse but growing body of measurements that are key to understand if warming of the Southern Ocean will cause the Ross Ice Shelf to melt.
Several of our team members also took time to uncover GPS equipment and ice penetrating radar (ApRES) that had been buried by several years’ worth of snow at two sites close to KIS-3, which were occupied by New Zealand colleagues at previous science campaigns in preparation for SWAIS2C. Data have been downloaded, and we are looking to redeploy the equipment at KIS-3 prior to final camp pull-out. We also moved some consumables that will be used for seismic experiments at Crary Ice Rise, the second drill site of SWAIS2C, now targeted for drilling in the 2025/2026 season.
Ollie Twigge and Martin "Paddy" Laughney deploying the mooring
We have achieved much this season and have learned a large amount about our challenging drilling process and environment. This new knowledge can only be gained through a field-based ‘shakedown’ and will ultimately help us achieve our goal to drill deep below the seafloor in this poorly understood region of Antarctica. We were thrilled when the almost two-meter-long sediment core arrived ‘on-deck’. In all, we return from the Ross Ice Shelf with 8 gravity cores and 3 hammer cores and a total 7.6 m of sediment.
Obviously, we want more, but the cores we did recover provide a new record of recent ice sheet and ice shelf retreat, a climate and environmental record that will be studied in detail over the coming months. We also have lots of sediment samples that will be studied for their microbiological content so that we can reveal more about the communities living in the extreme environment below the cold and dark ice shelf cavity.
And finally, we now know that the sediments below the seafloor at KIS-3 are relatively soft and that we can use our hydraulic piston corer with confidence – a big step forward as we sort important details for our drilling campaign. As the calendar crosses from 2023 to 2024, our team is already preparing to return to KIS-3 in November to complete our sediment drilling objectives. We can address the technical issue encountered with the AIDD system this season. Our drillers, engineers, and scientists have gained significant hands-on field-experience with both the hot water drill and the AIDD system, and how they ‘connect’. We can’t wait to return for the 2024/25 season!
