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The Stuck Ice Drill Saga; the team completes drilling

Monday, February 1st, 2010

The LARISSA ice core team has successfully drilled an ice core to bedrock (extending from the surface of the snow/ice to the Antarctic rock surface), reaching 445.65 meters. The team took less than a month at a campsite (Site Beta) in Antarctica to finish the job. During this time, the team experienced trouble with two drills used to recover ice cores. Being in the middle of a vast field of ice in Antarctica, the team had to use ingenious engineering tactics to work around problems. The story is included below:

Saga of the “stuck” Electrical-Thermal (ET) drill

“The LARISSA Bruce Plateau Science Team has the goal of drilling an ice core to bedrock (estimated to be 425 meters) on the Bruce Plateau in the Antarctic Peninsula. At approximately 2:00 PM on Thursday January 21 we experienced a seizure of the ET drill and it could not be extracted from the drill hole. The heating element (see photo) on the head of the drill that melts through to recover the ice core stopped heating because the heating element burned out due to water leaking into the coil. Immediately upon the “burnout” event the fresh meltwater at the head of the heater (at the very bottom the hole) froze in roughly 10 seconds and locked the drill in place at the bottom of the hole, which was 384 meters below the surface.

The initial approach was to pour several gallons of glycol-anti-freeze along the drill cable so that most of it would be delivered to the top of the drill. This was not successful and we determined later it is not a good practice as the glycol-anti-freeze dispersed on the top of the 130-meter thick column of ethanol-water solution. Thus it had virtually no impact. Quickly it was determined that the only chance of success would be to deliver the glycol-anti-freeze directly on top of the drill as was done by our team when the ET drill became trapped at about 380 meters during the 2002 drilling of a core to bedrock on the Bona-Churchill expedition. The different between these 2 situations is that on Bona-Churchill, there was no cable connected to the drill, but on Bruce Plateau the cable was still connected to the top of the drill. Thus, all of our efforts to reach the top of the drill had to also take into account the cable in the 130 mm diameter borehole. Several devices were designed and tested to pass through the 138 meter thick column of ethanol-water solution to deliver the glycol-anti-freeze directly on the top of the drill. At the same time there was concern that the borehole might begin to close due to ice flow or the diameter might be reduced by the formation of “slush” somewhere between the top of the ethanol-water solution column and the drill. In this case, even if we were to free the drill at the bottom we might not be able to bring it to the surface through a constricted borehole. We lowered and raised our bailer system multiple times to check the borehole diameter. We found that the diameter of the borehole was slightly constricted at about 288 meters depth. The reason for the constriction is not precisely known but was likely associated with a buildup of slush. Basically, we had two problems to overcome: (1) free the drill from the bottom of the borehole and (2) enlarge the diameter at the constriction so the drill could return to the surface.

Modifying a pump used to filter the ethanol-water solution and placing it into the bailer allowed ethanol to be squirted at the top of the constriction and then again at several other depths below the constriction. Next our bailer was modified to work not as a bailer which takes in water, but as a glycol-anti-freeze delivery system. The bottom of the bailer was redesigned to include a valve with a small activation rod that opened the valve when the rod touched the top of the drill. The bailer was then filled with the glycol-anti-freeze and delivered to the top of the drill. About 9 liters of glycol-anti-freeze was delivered to the top of the drill in two different runs. Subsequently, the drill cable was placed under tension and after waiting about 36 hours, the ice around the bottom of the drill had melted enough that the drill separated from the bottom of the borehole and could be raised to the surface (see photo). Interestingly, the drill barrel contained 66 cm of ice (see photo) that had been drilled before the drill became trapped. Our best estimate is that only 1 to 2 cm of ice was dissolved by the glycol-anti-freeze that settled at the bottom of the borehole (end of the drill).

This entire process, from when the drill became stuck to retrieving the drill safely to the surface, required almost exactly 5 days. During this time we received glycol-anti-freeze from Rothera and the Nathaniel B Palmer (ice breaker ship) that was working nearby in Berilairi Bay. In addition, the OSU team made numerous modifications to the equipment they had on hand with limited machining capacity. For example, the bailer that is normally used to take liquids from the borehole was modified to deliver glycol-anti-freeze to the top of the drill, to check the diameter of the borehole and to deliver a specific quantity of ethanol to multiple specific locations along the borehole wall. As just one example of the ingenuity required – we had no hose of the proper length and diameter to deliver the ethanol using the pump that was available. Thus the wires on the inside of a spare piece of drill cable were removed and the sheath on the drill cable was connected to the pump and placed in the bailer for ethanol delivery.

The drill was recovered at approximately 11:00 AM on January 26, it was repaired by 2:00 PM the same day and the team recovered 10-meters of new core before the end of the day. The photo shows the nearly 2-meter long piece of ice core that was drilled on the first run after the drill was extracted.

EPILOG: In the afternoon on January 31, 2010 the LARISSA ice core team’s electrical-thermal drill reached bedrock at a borehole depth of 445.65 m. The three photos, all taken on January 31, 2010, show (1) a nearly 2-meter long section of core recovered just above the bottom of the hole, (2) the last piece of core recovered from the borehole and the LARISSA drill team upon completion of drilling to bedrock on the Bruce Plateau, Antarctic Peninsula.”

Some new photos from the field, January 29th

Friday, January 29th, 2010

Updates for January 21st

Thursday, January 21st, 2010

From Ellen Mosley-Thompson on the ice core drilling progress: “Today we reached 350 meters in the long hole that is expected to be 425 m (± 5 m) deep.”

Here is a photo of one of the 2 meter ice cores that have been recovered:

Updates and photos from the field for Monday January 11

Monday, January 11th, 2010

From Ellen Mosley-Thompson: “We are doing well here. Thursday, we sent 21 more ice core boxes to Rothera for storage in the freezers. We have now drilled slightly more than 50% of the ice that we expected to drill.  We are changing to the thermal drill today.  It should take us roughly 12 days of drilling to reach bedrock if things go well.  Of course there are always challenges and surprises – plans are only made with the realization that they are likely to change. We are very optimistic that we will recover the Em drill that is [stuck] at about 140 meters in the Core A hole.  We do not plan to attempt to extract it until all the other projects are completed.

To date, we have sent 54 boxes of ice cores back to Rothera for storage in a freezer until the Nathaniel B Palmer (the NSF ice breaker) comes to pick them up and transport them to Port Hueneme, California. From there, the ice will be shipped in a freezer truck to The Ohio State University.”

Some more photos from the field camp are listed below (click to enlarge and view a description).

Photo credits: The aerial shots of the field camp are by Mike Clark (BAS).

Field Camp Photos

Thursday, January 7th, 2010

The Ice Core Team has sent back some photos (via satellite!) of their campsite at Site Beta:

Ice Core Team now in the field

Monday, January 4th, 2010

An update from the field:
“The group moved by Twin Otter from the English base of Rothera to the remote camp of LARISSA Site B on the glacier. Working in the polar night they installed the camp. They recovered, by using a ski-doo, some equipment that was left from a previous flight 15 km from the camp.

They started to drill the ice field and they quickly reached 140 m of depth. Unfortunately, the drill was lost shortly after because the cable got broken. Now they are trying to get the spare drill from the Rothera base and they hope to start to drill soon.”

Updates from Punta Arenas

Friday, December 18th, 2009

This morning, Friday December 18th, our scheduled flight to Rothera was cancelled due to bad weather in the vicinity of the Rothera Research Station, a major British Antarctic Survey base in the Antarctic Peninsula Region. Our team will spend roughly three days at Rothera (once we get there) assembling all the field and drilling equipment and prioritizing the cargo for the flights that will take us and all our equipment and supplies to the drill site. Of course, the exact date on which we will be flown to our drill site, called Site Beta or the LARISSA ice camp, will be determined by the weather.

The IPR (ice penetrating radar) team led by Ted Scambos of the National Snow and Ice Data Center at the University of Colorado returned to Punta Arenas from Rothera on Thursday, December 17. Our team met with them to exchange information as the IPR team spent roughly 8 days at Site Beta. During this time they mapped the ice thickness along multiple transects totally over 30 km distance. They identified an optimal drill site within the initial 8 km by 8 km grid selected earlier based on Satellite images and airborne radar surveys in 2002 and 2008 (see our Where are We Going? page). The ice thickness there is about 430 meters and the underlying surface (below the ice) is relatively flat. During their 8 days at Site Beta the IPR team experienced two storms with high winds that created significant drifting and buried some of their equipment. We will dig this out and use it at our camp. The second storm brought winds up to 60 knots and whiteout conditions. A challenge for our team will be to get our 24 foot diameter drilling dome up so that we will be able to work regardless of the weather. We will establish lines linking each structure to another to eliminate the possibility that someone will become lost as they move from tent to tent.

Ice Core Team currently in Punta Arenas, Chile

Thursday, December 17th, 2009

The team is currently in Punta Arenas, Chile as of Wednesday, December, 16th.

OHIO in Tierra del Fuego

The Ice Core Team doing the OHIO (with an extra O, Ellen Mosley-Thompson on right) in front of the Tierra del Fuego monument in the Plaza de Armes in Punta Arenas. Click to Enlarge.