TRIPLE-IceCraft Expedition to Antarctica – Drilling through the ice shelf - part 5
All of us on the team have been working towards this moment for the last few years: we will finally be able to operate our TRIPLE-IceCraft probe on the ice shelf and drill a deep hole there! The probe will now have to prove itself, and we are all very excited. After the successful four-metre-deep test drilling at Neumayer Station III a few days ago, we are optimistic and highly motivated. The transport of the melting probe to the drilling site with an 80-metre-thick ice shelf can start: at around 7:00 (local time), a colleague from the technical team prepares the snow crawler. The container containing the TRIPLE-IceCraft is released from the snow drift and driven forward. Meanwhile, we pack up the last things. In addition to our working container, we also have a living container and a transport sledge to be transported to the drilling site.##markend##
It takes the snow crawler almost two hours to drive to the drilling site, which is located about 18 kilometres away. Our team of operators leaves shortly after with snowmobiles and an Arctic Truck to arrive at the drilling site almost at the same time as the snow crawler. Around 10:00 (local time), we are on site. The containers are uncoupled, and ramps are pushed to the sides with the help of the snow crawler. The living container is parked a little away from the drilling site, so we can use it as an additional, large, comfortable living area without generator noise in the middle of the seemingly endless expanse of the ice shelf.
We prepare everything and again clear out everything necessary to operate the probe. The generator is started, and TRIPLE-IceCraft is pulled up by the crane. Just one more system check, and then the drilling can finally begin. In the meantime, it is early afternoon.
As expected, the next few hours are a little calmer. We monitor the drilling process of the probe, which is melting in at about three metres per hour, via our control software. This shows us status information and readings from all systems. Photos from the three cameras and measurements from the Forefield Reconnaissance System (FRS) are also displayed live. The images from the cameras are particularly exciting; we keep seeing different layers and structures in the ice channel.
At a depth of just over 11 metres, a subsystem suddenly stops sending status information. The power supply module for the systems is responsible for communication between the surface and the melting probe. The system also does not respond to manually sent commands. The communication between the surfaces and the melting probe is working, so we know the supply voltages are still being delivered. Nevertheless, it is not immediately obvious what is causing the error.
We prepare a complete restart of the probe, switch off the heating systems and let the melting probe cool down. Even after the restart, the module does not respond. We have to investigate and repair this on the surface. Therefore, we start the return journey of TRIPLE-IceCraft. After 'only' 11 metres, the disappointment is big but is quickly overcome by the urge to explore, get to the bottom of the cause, and fix the error.
After just under two hours, TRIPLE-IceCraft has returned to the facility. It is now after midnight, so we stow the essentials and drive the snowmobiles back to Neumayer Station III.
The next day is spent fixing the error and testing the system. To our amazement, the module starts again and communicates as usual. Even in the next few hours and through several restarts, we are unable to reproduce the error pattern. We use the time to further observe the system and improve our Fault Detection, Isolation, and Recovery (FDIR). Even into the evening, no faults occur. We decided to continue the drilling the next day. Unfortunately, we will not have enough time to break through the ice shelf as we had planned. Our return flight is scheduled in a few days, as a bad weather front has been announced. And before the flight, everything must be dismantled, safely stowed away and transported back to the vicinity of the station. We need two days for this. Therefore, we only have one day left for drilling, and we want to use it to drill as deep as possible so that we can gain further experience in operating the TRIPLE-IceCraft and record more measurement data.
We start early in the morning again, drive to the drilling site and use the existing hole for drilling. TRIPLE-IceCraft is set in place and drives into the melt channel at a speed of seven metres per hour. Once at the bottom, the probe sits up, and the winch system brakes automatically. Now we start the melting process again. It's back to waiting and monitoring. TRIPLE-IceCraft melts steadily deeper into the ice, this time without any unexpected events. In the camera images, we can see different layers of ice. From time to time, holes become visible where presumably the meltwater has run off. We take turns to monitor as we plan to drill deep into the night today.
It is getting darker and also noticeably colder. Around 22:00 (local time), we have to stop drilling and start retrieving the probe. In the meantime, we have melted more than 25 metres deep into the ice shelf. This corresponds to about one-third of the thickness of the ice shelf at the drilling site. The return journey with the rewinding of the cable into the interior of the probe also takes several hours. Shortly before 14:00 (local time), TRIPLE-IceCraft is completely back on the surface. We stow the essentials and arrive back at Neumayer Station III shortly before 16:00.
We will need the next one-and-a-half days to prepare the return transport of the probe and the associated material. The return transport to Germany will only take place when the next cargo ship arrives in December 2023/January 2024. Therefore, our material will remain close to Neumayer Station III during the Antarctic winter. We dismantle the crane and stow the TRIPLE-IceCraft and the rest of the equipment in the container. While waiting to be picked up, we are informed by radio that our return flight will be delayed by a few days. Unfortunately, the extra days are still not enough to unpack everything, continue drilling and pack it up again. Shortly afterwards, the snow crawler also arrives to pick up the two containers and the sledge. The TRIPLE IceCraft container is parked directly where it will stay for the next months in the Antarctic winter. The living container and the sledge will be unloaded near the station.
We use the next few days for documentation and to organise the return cargo. During the last nights at Neumayer Station III, we are lucky enough to observe a few more southern polar lights before heading north again.
First, we fly with Polar 5 to the Norwegian Antarctic station Troll. After a short stay with an overnight stay at Troll research station, we fly on to Cape Town. In Cape Town, we have a few hours at the airport before we take a scheduled flight to Amsterdam. A few more hours by car and we have made the return journey of over 50 hours.
Despite the unexpected challenges, we managed to successfully deploy our TRIPLE-IceCraft melt probe in the harsh conditions of Antarctica! We drilled two boreholes, one of them 25 metres deep. The fault that occurred could not yet be clearly identified, but it could be narrowed down considerably. Through troubleshooting, other possible fault cases could also already be identified. We have adapted our FDIR accordingly to catch these error cases in the future. We learned a lot about the system during the test, recorded a lot of measurement data and are now looking forward to analysing the data.
Back in Aachen, we will continue to run our engineering model of the probe. This will allow us to investigate the identified errors further in order to rule out their recurrence in future missions. We will do our utmost to test TRIPLE-IceCraft in the ice again as soon as possible and deploy it even deeper to eventually reach the ocean beneath the ice shelf.