11 July 2017
Tuesday 11th of July 2017

Marius having a look at the ice core piece he just managed to drill sideways.

Drilling cores sideways

As the drillers are steadily decreasing the inclination in the bore hole a challenge encountered previously in the field season has returned: Floating pieces of ice core in the bore hole. When an ice core is drilled, it has to be broken off the underlying ice in order to be pulled to the surface. If the core breaks at more than one location, the bottom section can sometimes dislodge itself from the drill on its way to the surface. Then we have a core section floating in the liquid filled bore hole. Normally such pieces are extremely difficult to retrieve in a fair condition, but today Marius and Steffen managed to bring a floating piece almost intact to the surface by re-drilling it sideways! Something I have only seen done once before – also here at EGRIP.

Otherwise ice core production was good, but extraction of the ice core from the core barrel was hampered by a slight imperfection that had appeared in the core barrel, which turned out to be detrimental to the increasingly brittle ice. This issue was, however, solved as soon as it was identified. Logging proceeds as normal.

On the surface, the AWI drill setup was again tested in production mode yielding almost 35 m of firn and ice core. At a depth of approx. 45 m the drill head was changed to one with smaller diameter (kindly provided by Steffen), as the diameter of the original head seemed to be too large for drilling in the more dense layers below. With the new drill head, drilling again proceeded nicely.

The normal surface program continued as planned and a 2 meter pit was sampled at the A2-17 core site. Physical properties measurements also proceeded as planned.

In order to make sure we have a good skiway for the flight period starting 9 days from now, Chris begun the grooming using a Pistenbully most of the day.

What we did today:

  1. Grooming of skiway.
  2. Deep drilling core length at 19.00: 15.66 m.
  3. Logging depth at 19.00: 638.49 m.
  4. Water vapour, methane, aerosols, snow and boundary layer measurements
  5. Physical properties measurements.
  6. Sampling auger core A2-17 pit to 2 meters depth.
  7. Continued drill test for AWI system, drilled from 28.15 m to 62.62 m.
  8. Driving autonomous vehicle north of camp.

Weather: Sunny day until late in the evening then foggy. Wind turned from SW to W during the day, up to 5 m/s. Temperature between -20°C and -9°C.

FL, Bo Vinther

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