May 25, 2023

Reaching 2500 m depth and speeding up drilling

Five nationalities in science and drill trenches celebrating 2500 m logged core: Grant, Josie, Nico, Yannick, Ashish and Kenji.

Today the ice core production was increased by 100% compared to yesterday, but not only that, the quality of the cores is also the best we have seen for a week. No broken sections and no core catcher scratches along the core whatsoever. Now, if this change in core quality is related to the new drill head configuration with three core catchers mounted, or whether it is related to a change of ice properties, we do not know. The change in physical properties of the ice is associated with a climatic cooling transition (onset of GS-22) that we see as a change from cold to mild, because we are drilling backwards in time. The ice from the cold climatic period has high impurity content and small ice crystals, whereas the ice from the mild climatic period has lower impurity content and larger ice crystals. The ice with the smaller crystals is known to be ‘softer’ and easier to deform, which may be the reason for the long core catcher tracks occurring in this ice only. For now, we pragmatically decide it is a combination of the two changes that caused the improved core quality. We may get wiser some 15.000 years further back in time, when we will hit the next abrupt climate transition (onset of GI-23).

The trenches celebrated the last 500 m depth mark to be reached and Tim spent another day removing drift snow and ski tracks from the skiway.

What we did today:

1. Started drilling in teams. Four long ice cores drilled today.
2. Logging depth: 2506.59 m. Processing depth: 2503.60 m.
3. Repair of hammer position sensor in motor section.
4. Continued beam grooming skiway after Skier mission and drift.
5. Giving weather to our Greendrill friends that are stuck at a windy site.
6. More physical exercises in main Dome directed by Hans. The camp is as fit as ever.

Weather today: Blue sky most of the day. Temperatures -21°C to -32°C. Westerly wind up to 14 kt at noon dropping to 6 kt in the evening.

FL, Anders Svensson

Palle is busy repairing the hammer position sensor in the motor section of the drill. 3D printer is busy in the background producing holders for the ‘Pinger’ microphone and speaker.