21 January 2025
Weather at 6pm: Temp –23°C; Wind 16 kn
This morning we completed recovery of chips left by the first reamer. Then we switched to the 209 mm reamer. The target depth for this second of the three main reaming steps is 125 metres. As of writing we down to 70 metres.
The reaming system, built by our drill engineer Etienne, is working very well. As with the small reamer, the chip loss (i.e. chips that are not captured in the reamer barrel and instead lost to the bottom of the borehole) is manageable. We are dropping about 1 metre per 20 metres reamed. Less loss would be possible if we take a smaller cut and tighter tolerance of the reamer barrel in the borehole, but at increased risk of getting the reamer stuck. Fishing for chips is better than stuck reamers, so we play it conservative.
The sketch shows what we are trying to achieve with this reaming process. In a series of steps we increase the dimeter of the borehole from the 130 mm diameter made by the drill, out to 260 mm. This larger diameter is to install our 255 mm borehole casing. The casing will provide a sealed column past the porous firn and into the glacial ice (firn is ice of a consistency between snow and glacial ice, usually in the top 90 metres).
In a final step, not shown in the figure, we will ream a short section from 120 metres depth out to 222 mm, to fit a specially machined piece of casing with o-rings and tapered profile that is intended to seal with the glacial ice at that depth. This will allow the deep drill to access the glacial ice next season.
To finish all the reaming steps, the combined total to drill and ream is 525 metres. We’re at 350 metres, so we are two thirds the way there!
22 January 2025
Weather at 6pm: Temp –25°C; Wind 10 to 20 kn
A cold and windy day at DCN and successful completion of the second reaming step to 125m.
Today we reamed a further 55 metres, completing the second reaming step to the target depth of 125 metres.
Ten metres of chips were dropped to the bottom of the borehole by the second reamer. The late shift is currently swapped back to the drill and fishing these out. Tomorrow we will change to the ‘big bertha’ 260 mm reamer for the final of the main reaming steps.
To finish all the reaming steps, the combined total to drill and ream is 525 metres and we’re now at 405 metres - see the sketch below for where we are, and what we have to go.
Outside the drill shelter we moved our super-insulated TerraVac box out of the firn trench, where it was being cold soaked. The TerraVac box has vacuum panel walls and embedded phase change material. It’s a passive (unpowered) solution to transport ice cores on the traverse to Casey and then by C17 back to Australia. This season 192 metres of ice core will be taken back inside the box.
The traverse crew continue with cargo operations, vehicle work and the preparation and staging of equipment for next season.
We had a visit from two parties from Concordia station, including the Concordia Station Leader, Riccardo Scipinotti. The cooperation and spirit of community shown to us by Concordia has been remarkable and it was nice to return some of the warm hospitality they have shown us.
23 January 2025
Weather at 6pm: Temp −24.5°C; Wind 6kn
With the second reaming step completed, and all chips diligently drilled out yesterday by the night shift, this morning we changed to the largest reamer. This one is too big to tilt on the tower, so we changed the drill to tall boom configuration and dropped the chips out vertically into a sled. Changing the drill to this configuration takes about two hours.
The reaming itself went well, and shortly after lunch we were at 47 metres, but then some difficulties started. Using our rope measure, we found about 11 metres of chips at the bottom of the borehole. This is too much for comfort. Any more than 15 metres of chips and it will be difficult to get them out, because the anti-torque on the drill will be sitting up in the reamed part of the borehole above 130 metres. So we changed back to the drill again. After recovering four metres of chips the drill motor lost power and we noticed a worsening transmission fluid leak.
Etienne and Tim opened the motor to find an ugly sight (see pic), the motor is toast. But not to panic! We have a spare. As I write, this is being swapped in and a seal in the transmission replaced to fix the oil leak. We’ll also make some adjustments to reduce the chip loss.
Meanwhile, outside the drill shelter, Daniel completed the remaining ApRES stations, with combination of strain rate measurements to monitor ice thinning, polarimetric measurements for ice fabric, and further trialling of the prototype Dual DDS ApRES, designed for increased sensitivity in deep ice (lent to us by British Antarctic Survey).
To finish all the reaming steps, the combined total to drill and ream is 525 metres. We’re now at 453 metres and we have only a few days left on site. We are very motivated to finish the reaming this season, but it is something that must not be rushed.
24 January 2025
Weather at 6pm: Temp −25°C; Wind 3 kn
A terrific day. We finished the final reaming step to 120 metres. Everyone came in to the drill tent to see the final run. Champagne was served and deserved and we celebrated the successful season.
Since the science and traverse teams joined up at Dome C North on 1 Jan we have completed the construction of the drill shelter, dug the deep drill trench, completed a test core to 50 metres, completed pilot drilling the main MYIC core to 150 metres, and completed the three reaming steps to expand the borehole to 260 mm, ready for installation of the bore casing next season. Thanks to the efforts of this remarkable team, the MYIC project is set up well for the seasons of deep drilling ahead.
We have managed to finish the main reaming just in time, as most of the science team fly tomorrow (if the weather agrees) from Concordia back to Casey. Etienne and I will remain on site for a few more days and are scheduled to fly from Concordia on 31 January. We're staying to complete a final short 222 mm ream at 120 metres, where the casing will seat into the glacial ice, and to pack up the drill.
As well as completing the main reaming today, there was a massive effort this morning to dig out all the ice core boxes from the firn trench. Triple helpings of nachos and cake for smoko sustained the diggers. 192 metres of ice core were then loaded into the TerraVac box. The box wall temperature (which contains frozen phase change material) is reading −27°C. The phase change material and vacuum panel walls will keep the ice cores cold for the approximately 15-day return traverse journey to Casey, even as temperatures warm closer to the coast.
The camp is now in pack down mode with equipment being prepared to winter here or readied for the return traverse.
25 January 2025
Weather at 5pm: Temp −23°C; Wind 4 kn
The borehole trapdoor is now shut until 2025–26 and the science at MYIC Dome C North has wrapped up for the year.
Chelsea, Chris, Daniel, Derryn and Chippy Dave flew from Concordia back to Casey this morning. All have made super contributions to the project. Chelsea and Chris expertly led the core logging and completed all the Kovacs coring. Daniel drilled and reamed a lot of metres and completed all our ApRES stations. Derryn led the late shift drilling and fixed a bunch of electrical problems that could have stalled our drilling. Chippy Dave led a very precise and efficient drill shelter build, true to his motto ‘aim small, miss small’.
The last drilling and reaming tasks for today were to drill out the chips left by the larger reamer and then make the short but important 222 mm ream at 120 metres depth, where the bore casing will seat into the glacial ice when it is installed next year. Etienne and I stayed on to complete this job. Reaming is a tense business. A miscalculation on depth of run or cutter size can stick a reamer in the borehole and end drilling. It was such a relief to see the reamer come back to the surface for the last time this season and with the full reaming profile complete and without incident. Congratulations to Etienne who built the set of reamers for this project, which have performed so well.
Tomorrow we will pack down the Eclipse drill, prepare the drill shelter for its winter vigil, and have an Australia Day BBQ on the ice.
The traverse team aim to depart on 28 January. Safe travels, thanks and respect for the hard work and commitment that has allowed MYIC to get so much done here in only four weeks. Before traverse leaves they will drop Etienne and I at Concordia Station, where we will wait for a flight back to Casey when weather allows it.
Until next season!
Joel Pedro
MYIC Science Lead
