22 May 2009

A long ice core

The new water vapour sampling site.

The new water vapour sampling site.

It has been a blusterous day. Snow began to move after Noon. For Henry it was quite annoying. He is currently excavating a 6 m deep trench with the snow blower, and when snow is on the move, it will find the first depression to fill up, which was Henry’s. In the end he decided to abandon this “Sisyfos”-work and, as soon as he did, the wind abated. Sarah has got a new mixer, a biggy weighing 100 kg. She was so happy; she immediately showed what it could by making homemade pizza. In the drilling trench, they have drilled 10 m ice core with the EPICA drill today. Cores of more than 2 m length were drilled. Trevor exclaimed: “We haven’t drilled a two meter core since 2000”. Come to think about it, it is in fact true. 2000 was the last year we used our long drill at NGRIP. In 2001, 2003 and 2004 we used the HT drill, because of warm ice at the base at NGRIP. At Flade Isblink in 2007 we used the HT drill, and this year at NEEM – until now.

What we have done today:

  1. Drilling.
  2. Installing tables in CFA room.
  3. Excavating inclined trench to drill trench.
  4. Work on electrical installations.
  5. Moving snow in camp (removed snow drifts).
  6. Water vapour sampling site ready.
  7. Cutting away section of side wall in science trench.
  8. Organizing mattresses, pillows etc. for bed in new weatherports. Made bed count in camp.
  9. Repairing no. 3 winch controller.

Ad.1: This is how the drillers report looks today:

“We had a good and wet day in the drill trench. Wet drilling began today with the EPICA drill in the new drill liquid. For the first four runs we used the same 134 mm cutter configuration with a pitch of 4.5 mm as we had with the dry drilling. In this mode the 4 meter long chip chamber was full after a maximum core length of about 2.4 meters due to the excess chips produced with these wide cutters. The drill produced nice course chips and the drilling liquid performed beautifully transporting chips efficiently leaving a clean borehole after each run. In an effort to stabilize drilling motor current and to drill with a negative cutter load, we reduced the cutting pitch to 3 mm for a final run. This run produced a 2.2 meter core and a full chip chamber, but had a long drill time and still required slight positive cutter load (4-8 kg). A more aggressive cutter pitch seems a better mode so far. With each run the drilling software was optimized and the new display and control is well liked by the drillers. All drilling today was done with the backup winch control giving us two perfectly functioning winch controls. The core extraction table and logging tables were completed in the drill trench. Driller’s Depth 120.0 meters (~131 meters from 2008 surface)”

Weather: Clear all day, fog in the evening, - 19 °C to -12 °C, 12-23 knots mainly from SSW.
Visibility: 1-3 km. Fog and blowing snow. Windy day.

FL, J.P. Steffensen


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