The season has come to an end. We departed South Pole on January 30th after a very productive and successful 3-month season. The 2014-2015 season goal of the SPICE Core was to reach a depth of 700 meters, which we accomplished and then some. Our final depth was 736 meters. Of that, about 600 meters is making its way onto the vessel currently docked at McMurdo Station for its transport back to the United States. In June (or somewhere around there), the ice core processing line will take place at the National Ice Core Laboratory in Denver, CO. This is where all the samples of ice will be cut and shipped to funded labs across the U.S. Hopefully by August, I'll be doing my experiments on the ice that we brought up this season!
It is the last week of drilling here at the Pole. As of today (Jan. 21st), we’ve reached a depth of 690 meters! Only 10 more meters to go until we reach the season goal of 700 meters. At the current depth, the ice is around 10,000 years old!
In the picture above, you’ll see that the ice core is in a green netting. Any guesses as to why we’d put the ice core in netting? Well, it is because we have reached what ice core scientists call “brittle ice”. Brittle ice occurs with depth in an ice sheet where the tiny air bubbles that are trapped inside the ice are under high amounts of pressure. When we bring the ice up to atmospheric pressure very quickly, the tiny bubbles want to burst because they no longer have as much pressure pushing on them. By handling the ice core and moving it around, we can actually induce breaks and fractures in the ice because the bubbles are very pressurized. We want to reduce the amount of breaking because our goal is to preserve the trapped ancient air to study it! In order to prevent excessive breaking, we immediately put the brittle ice cores inside netting to help reduce damage to the core and ensure that if breaks or popping occurs, the pieces stay in the right spots. These cores are then kept in our ice storage trench over the winter to provide more time to relax the internal stresses and next year we will processes them and get them ready to be shipped back to the National Ice Core Lab (NICL) in Denver, CO. .
The core also has drilling fluid on its exterior and we don’t want to ship drilling fluid back to NICL for several reasons. The first is that the drill fluid is not cheap and we want to recycle and reuse as much as possible. Recycling the fluid keeps us from having to ship more all the way to the South Pole. Also, the drill fluid we are using does have a slight smell that we don’t want to get stuck in a freezer for many years. Therefore, to remove the drill fluid from the netted ice cores, my job is to vacuum the core! This procedure removes quite a bit of the drill fluid. It is also very relaxing for me – makes me feel like I’m at home cleaning my house :)
On average, we drill about 24 meters per day between two 10-hour shifts. Each run of the drill is taking slightly longer because the drill has move distance to travel each time it goes up and down the borehole. A typical run from surface, down to drill and collect a 2-meter long core, and back up to the surface takes close to an hour. It is amazing to think that the drill goes nearly half of a mile down into the ice sheet and back up with more ice core in just an hour! AH, ice core science and engineering are so amazing.
Hope you all are staying warm in you respective homes. It’s currently -48 deg Celsius here (-47 deg F)!
Until next time,
The photo above is a picture of our first visible volcanic ash layer in the SPICE core. We noticed this layer at around 306.5 meters and we're quite excited to finally see something in the ice! After some researching, we discovered that this volcanic event occurred around 3,200 - 3,500 years ago and was from a volcano in the Southern Sandwich Islands. Scientists can trace back volcanic events by analyzing the chemical species and rock types found in the ash layers in ice cores and using it like DNA for the volcano. They then travel to different volcanoes around the world and analyze the chemical species of the rocks of many volcanoes and then try to match which volcano is repsonsible for a given ash layer in an ice core by
Welcome 2015! I hope the New Year has met you all well. Here at the South Pole, each January 1st the geographic South Pole marker is replaced and moved 33.06 feet. The reason for the move is because the ice sheet is flowing and the marker moves synchronously with the ice! Therefore, at the start of each year, surveyors map out 33.06 feet and place the new geographic marker back at the true geographic South Pole. The design of the new marker is voted upon during the previous winter (March-Oct) and the winter-over machinist creates it! Thus, 2015’s marker was designed during the winter months of 2014. It is a great tradition and this year’s marker is quite beautiful! During the unveiling ceremony, everyone at the station formed a half-circle around the old marker and the new marker and passed the American flag around to its new location 33.06 feet away next to the new geographic South Pole maker. Having the opportunity to participate in this event was quite moving and makes me extremely thankful for the chance to be doing science at the South Pole!
Until next time,
The last few weeks here at the South Pole have been very busy and festive! We started wet drilling on December 26th. We use a drill fluid (thus the term “wet) to help lubricate the drill and ice and make it easier to extract the ice. The drill fluid also helps to keep the borehole open because at deep depths in the ice sheet, the pressure is incredibly high and will ultimately squeeze the hole we cored shut. The drill fluid has a similar or slightly higher density than the ice and will keep the hole open. As of today, we have reached a depth of 260 meters, about one-third of our season goal of 700 meters! We are also working shifts now. I’m on the 7am – 5pm shift.
Christmas at the South Pole was a blast! On Christmas Day morning, the majority of the station takes part in the “Race Around the World”, a 1.75 mile race outside around the station and surrounding science buildings. Most people dressed up in crazy costumes and the firefighters on station “raced” with all of their bunker gear on! It was definitely an awesome experience. Our Christmas dinner was delicious and a dance party followed.
My birthday also occurred this past week (December 28th). Although I had to work, it was still a fantastic day. My morning started with me walking into the break room at the drill site with birthday decorations and a card signed by many of my station friends! At dinner, I was surprised with a mini-cookie cake made by the baker. All in all, it was a great birthday at the South Pole.
I hope you all had a great holiday week!
Until next time,
Mindy Nicewonger is a PhD candidate in the Department of Earth System Science at the University of California, Irvine.
Banner photo: Mindy standing in front of the C-130 Hercules in McMurdo, Antarctica (Nov. 2014).