North GReenland Icecore Project - Diary for week 30

Daily reports from the NGRIP-camp - week 30 year 2001

Monday, July 23rd
Daily life
The nice weather is over for now. Today has been quite windy, and snow was blowing around in camp again.
Science
Three bailing runs have been performed, and 40 kg of glycol, slush and cuttings have been brought to the surface. The bailing runs have advanced down to 2m above the bottom of the hole. At the same time the freezer used for freezing glycol has been repaired. This freezer has to go down to -55 °C for glycol to freeze. Before putting glycol into the drill hole the glycol is frozen in small tablets. In this ways the glycol will fall all the way to the bottom of the hole before melting and reacting with the ice. In order to get at better understanding of what exactly happens at the high temperatures in the hole experiments on freezing glycol are conducted.
Logistics

Tuesday, July 24th
Daily life
Still windy with some snow fall.
Science
Another bailing run has been performed, this time resulting in 6 kg of slush. There have been some problems with shortcuts during the bailing runs, but apparently they have been solved. The experiments with freezing glycol continue.
Logistics
The skiway was groomed again after yesterdays blowing snow.

Wednesday, July 25th
Daily life
The weather has improved again: sunny, no wind and -10 °C.
Science
The drilling started again! One 10 cm core has been drilled sofar. The top of the core was somewhat damaged after the problems following the 8th of July, but that had to be expected. Before the first drill run the hole was logged again. The temperatures found were -5.2 °C 2m above the bottom and -4.6°C at the bottom. The temperatures at the bottom of the hole are still mysterious, and calculations are being done on whether the high temperatures could result from heat released from either the glycol or the drilling.
Logistics
The grooming of the skiway is finished for now.

Thursday, July 26th
Daily life
An overcast day with some wind. Working outside is not very exciting in this weather, instead the kitchen was cleaned thoroughly.
Science
A bit more than 3m's have been drilled since yesterday, so this is good news. Moreover there haven't been problems with the ice cores freezing onto the core barrel. This probably means that there is not much glycol left in the borehole. The very high temperatures at the bottom of the borehole are probably caused by heat from the drilling. As a consequence drilling procedures have been changed somewhat in order to minimize the heating. The drill now only starts rotation shortly above the bottom, and cooler drill liquid is brought down from above. In Copenhagen the oxygen stable isotope concentration has been measured on the first samples sent down from the camp. No indication of the Eemian yet, we're still waiting!
Logistics
Minor repairs have been performed in camp. There were new problems with the power supply, this time probably caused by the stove in the kitchen.

Friday, July 27th
Daily life

Science
The drilling has reached a depth of 2999,72m. Hopefully the 3000m will be reached tomorrow in time for a saturday evening celebration. The drilling was slow today. The inner and outer core barrels were frozen together after the first runs, and despite several modifications only short cores were drilled today. The experiments with freezing ice and glycol have been finished.The purpose was to get a better understanding of what exactly happens in the borehole when then glycol melts in the drill liquid and reacts with the surrounding ice. At what temperature does the glycol-water mixture freeze, at what speed and how much heat is drown from/released to the surroundings? Experiments with mixtures of water and glycol have been conducted at temperatures between -5C and -10C. The mixtures freeze at about these temperatures, and during freezing the temperature stays at the melting point of the mixture for a long time. It had been speculated whether the freezing process could actually release heat warming the borehole, but this has not been confirmed by the experiments.
Logistics
Snow has been moved from the main dome, and "Skiway 21" has been groomed. This is an alternative skiway, orthogonal to the main skiway.

Saturday, July 28th
Daily life
The weather has been changing between sunny and overcast during the last days. Temperatures are around -10C.
Science
The drill got stuck again! Friday evening the drill got stuck for the fourth time this season. Frozen glycol was dropped into the borehole several times, while pulling at the cable with 1.8 tons. Today the drill got finally free at 17.50, and it reached the surface 90 minutes later. At the surface it was noted, that two of the three core dogs had clear ice on them, as if they had been in contact with liquid water. Now several small repairs have to be performed on the drill and the borehole has to be cleaned from glycol again, before the drilling can resume. Maybe it is simply not possible to drill through the last warm part of the ice with a mechanical drill ...
Logistics
There have been problems with the Herman Nelson heaters used in the drill trench for cleaning the drill from water and glycol.

Sunday, July 29th
Daily life
A minor blizzard today with wind speeds about 25 kn. All entrances to the trenches are filled with blowing snow again ...
Science
The 3000 m were reached today. While bailing the borehole short cores are also being drilled. Unfortunately the glycol makes the cores freeze onto the core barrel, which has to be heated somewhat for the cores to get out.
Logistics

Continue to Week 31