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Under the Glacier!

Photo credit: Britney Schmidt

We have made it, folks. Yesterday Icefin was driven under Erebus Glacier Tongue towards the grounding line! In the image below you can see the glacier tongue, which is the jagged piece of thick ice extending into the sea ice. For scale, our camp is the cluster of dark blobs near the center-left of the photo, in the corner between the glacier and land ice. This has been a major goal of the season, for several reasons.

Photo credit: Spencer Niebuhr

Firstly, and most importantly, the grounding line is a very difficult place to image. It’s the spot where a glacier, which is land-based ice that flows under its own weight, loses contact with the ground and begins floating in a body of water. While we can learn about this area using radar, a person or ship can’t actually swim or drive down to it. That’s where AUV’s and ROV’s come in, to image the grounding line using high definition video, sonar, and oceanographic sensors. So it’s a big deal to get to the grounding line at all.

But secondly, it marks an important step towards a larger goal of the RISEUP project: to explore the grounding line of the Ross Ice Shelf. Next year Icefin will be deployed through a hot water drill hole that goes through over 800 m of ice to reach the ocean. The water here is more than 1000 km from the edge of the ice shelf and receives no incoming sunlight. It’s these reasons that make it an excellent analog for an icy moon, which may have little interaction between the ocean and atmosphere on either side of the ice shell. Knowing that we can operate Icefin in an “easier” (hah!) grounding line environment gives us confidence that next year we will be able to collect a one-of-a-kind dataset from a much more challenging location.

And it’s not just the robot performing well. The team is operating as a cohesive unit, which translates to efficiency in deployment, diving, communication.. and even getting back to base in time for burrito bar. We also find some little moments in the field to enjoy the stunning location. And how better to enjoy ice than by curling on it?

On a no-dive day we also took the opportunity for a reconnaissance mission. Britney, Justin, and I went to tag up with our New Zealand colleagues at their camp in the middle of McMurdo Sound to learn about their oceanographic instrumentation and methods in preparation for our work together next year (https://www.instagram.com/the_ross_ice_shelf_programme/?hl=en), and discuss operations for our next project with them. And by the way — congrats to PI Inga Smith on her newly selected Marsden proposal (read more here: https://www.otago.ac.nz/news/news/otago698925.html)! They’ve been there for several weeks taking measurements of ocean properties in one of the deepest parts of the sound. It was great to see what they’re working on first hand, and talk about the deep drill site for next year.

Photo credit: Britney Schmidt

After that, we headed north to check out our other sites: Barne Glacier and Evan’s Ice Wall. We scoped out a place to setup camp near Barne Glacier, an awe-inspiring mass of ice calving off into McMurdo Sound. A sea ice crack running toward Barne made a perfect place for us to take a CTD cast before we headed off.

Photo credit: Justin Lawrence

And just as we were headed home: the best part of the day. A group of 6 emperor penguins were standing at the side of the road, presumably waiting for the penguin shuttle bus that takes them to the fish store? We steered clear of them, and parked our snow mobiles about 50 m away. They decided to come check us out, however, giving us an up close view of these beautiful animals. And also the rare opportunity for a penguin selfie.

Photo credit: Britney Schmidt

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Out to Erebus Glacier Tongue

In the time since the last post we’ve been busy alternating diving days and days for analyzing data, adjusting, and planning missions. We’ve been able to improve our navigation strategies and better estimate the location uncertainty when we operate in different travel modes (ex: driving the robot manually or letting the vehicle drive itself between waypoints).

All of this work at the Scott Base Shelf Site allows us to start to image the transition between sea ice, where our fish hut sits, and the ice shelf. The thickness between these two units is roughly 3m for the sea ice versus about 25m for the edge of the shelf here. There’s also a big change in the ice provenance – which just means “where it comes from”. Shelf ice is glacial ice, from the continental ice sheet, that has flowed off the continent and over the ocean. It floats, but is still attached to and sourced from land. As we have covered in previous entries, sea ice forms in the water column and floats up.

Photo credit: Andy Mullen

After several dives near Scott Base we have switched operations to Erebus Glacier Tongue, which has some important logistical challenges. It’s a 2-3 hour drive each way in the PistenBully, or a little over an hour by snowmobile. There’s limited communications over radio, so we have to keep in touch with McMurdo by satellite phone. The sea ice is significantly more cracked and exposed than it is near town, because of the glacier tongue interacting with the sea ice. And the tongue itself is quite unstable, making it impossible for us to go anywhere within about 100m of the glacier. Perhaps most importantly, we deploy here using a large metal A-frame that sits over the hole and adjacent to an operations tent with room for about half the team. Setting these structures up is not trivial, and you’re fully exposed to the weather while doing so.

Photo credit: Britney Schmidt

We certainly felt the weight of those challenges trying to get our camp setup. Attempt 1: we packed up with all of the necessary gear (so much stuff!) to create a base out of nothing, but halfway there had a problem with our PistenBully wheel and had to turn around. Attempt 2: we got up bright and early, but still ended up getting turned around by bad weather after only a handful of hours on site. Attempt 3: we finally got the A-frame installed and the hole excavated. After 3 tries, we were ready to dive the following day. #Antarctica, right?

Photo credit: Dan Dichek

When we did make it out we had the pleasure of spending the day with the crew from NOVA (https://www.pbs.org/wgbh/nova/), as they’re filming a series of videos about science and life in Antarctica. Luckily the weather cooperated with clear sunny skies and mild temperatures, which is preferable when operating camera equipment.

Photo credit: Andy Mullen

We’ve also gotten lucky with the local macrofauna: our drive to the glacier tongue takes us near a couple packs of Weddell Seals.

Photo credit: Frances Bryson

In the interim, McMurdo continues to be an awesome place to work out of. Folks are certainly enthusiastic about Halloween, and only a couple weeks left until Thanksgiving! Smaller events mark the community calendar, too, like a craft fair, salsa classes, and group meditation. Now who said there are no polar bears in Antarctica?