Unlike the Arctic, which is mostly water surrounded by land, Antarctica is land surrounded by water. 50 million years ago, it was filled with green and life, but then over time, massive ice sheets formed, covering the continent and turning it into what we know today. These sheets, the east one south of the Americas and the west one south of Oceania, form the bulk of the ice on the continent. These sheets are so massive, two or three kilometers thick, that they actually push ice outwards towards the coasts, forming rivers of ice that are known as glaciers. The glaciers flow outwards towards the coasts, spilling over the edge of the continent and forming ice shelves, which are near-permanent literal ice overhangs that float above the ocean; the Ross Ice Shelf is one of the most famous of these, which is right near where we are (and where we’ll be later in the season). The shelves are up to a kilometer closest to the glacier, thinning as they get farther out, with the edge calving occasionally to form icebergs. In the winter, things get so cold that the oceans themselves also freeze; this is what’s known as sea ice, and is the most dynamic of the four. For sea ice training, this is what we went out to learn how to survive on.
Survival on the sea ice is most critically about situational awareness, also known as paying close attention to the conditions and your surroundings, staying on the lookout for cracks. Cracks in the sea ice are the biggest hazard when travelling around out there; they can shift and widen in a matter of hours, appear and disappear within days, and be covered in multiple feet of snow that can give out at any time. These form for a variety of reasons, most notably because it’s floating on the ocean, which is a dynamic environment already. The tides, for instance, cause the ice to seem to “breathe”, rising up and down over the course of a day, and the pressure from the glacial inflow can be immense. Cracks are often found jutting off islands in the ice or other discontinuities, such as glacial tongues or peninsulas, where the pressure builds as the ice flows outwards. Some are temporary and ethereal, appearing for short times and the closing quickly. Others are seasonal, showing up in similar locations year after year. These are often named for things that have fallen into them; the Big John Crack is named for a vehicle that was named John falling in, for instance, and is found in nearly the same place every year just off the station a bit. Some are very small, hairline cracks that are relatively frequent, while some are quite a bit larger, measuring seven meters wide or longer! Keeping a sharp lookout can help to mitigate the risks, but even the most seasoned of drivers can be fooled, even in good weather, so it’s critical to maintain focus lest you get stuck.
We spent the day traversing the ice with Pete, a mountaineering guide who spends his “summers” here working as a route flagger and resident sea ice expert. It’s the first time out on the sea ice for Dan, Josh, Chad, and I, and we excitedly pile into the back of the hagglund for the trip. This “science caterpillar,” as they are affectionately called, is similar to a two-cabin pisten bully; it’s a tracked vehicle with a top speed of about 15 miles an hour and a very weak door hinge, but great for moving around out there. After an hour of learning, “MacOps, MacOps, this is hagglund 321, on MacOps,” Pete radios as we get to the transition, where the land of Ross Island meets the sea ice of the Ross Sea. He informs the operations center of McMurdo that nine “souls” are heading off to the ice, with an estimated return of 1700 hours. MacOps confirms, and we head out.
The first crack we stop at is a seasonal one called Backhoe crack, named for (appropriately) a backhoe that got stuck in it at some point. As the biweekly sea ice report states, it hasn’t moved in six weeks, but as newbies to this, we stop and all get out to take our first, um, crack at measuring the crack. Backhoe is a straight-edge crack, meaning that there is a single step from the top of the ice to the bottom, and there are guidelines about how wide and deep a crack can be for various vehicles to drive over them. The first step is to determine the width, which is done using a very high-tech device called a shovel; find the near edge and dig down and out until the far edge is reached. Measuring is also high tech; a strip of measuring tape, starting at 76.30 meters, on a reel with a steel cable. We dig it out, measure, determine it still hasn’t moved and is within the specs for the hagglund, and continue on.
The second crack is the aforementioned Big John Crack. This one also hasn’t been moving in a while, and after a quick dig-and-measure, we move on to the north, around Hut Point toward our destination for the day: the southern edge of the Erebus Glacier Tongue (EGT), which we’re hoping to scout for a potential hole site for Icefin. It’s a forty-five minute drive to our first stop after Big John – a very large crack that was discovered a few weeks prior near one of the seal team huts. The seals are fat and adorably lazy; they give us only a passing glance as we check out the seventeen-meter-wide crack without a name that is mostly covered in snow. Pete points out that this is the kind of danger we face on the ice; big cracks that are covered in snow are hard to spot but easy to fall into. The seals are a giveaway since the ice is thinner in the crack, making it much easier for them to dig their holes and maintain them; their lives are often limited by their teeth, since they need sharp teeth to eat out and maintain these holes, allowing them to get under the ice to feed. We continue on.
After the seals, the flags end, and we’re on our own over the rafted ice. This type of surface looks like the ocean has literally frozen in place, with waves of ice spreading in all directions. It’s a really amazing sight, otherworldly and eerie. We stop at a hairline crack to learn how to use the Echo drill, a two inch diameter drill that uses meter-long “flights” to drill deep into the ice. The flights are essentially meter-long screws that extend the cutting bit down deeper; Chad has the honor of drilling. The first flight yields only ice, as does the second. At the end of the third he finally breaks through, bringing up water and platelet ice. Platelet ice is an exotic type of ice that forms underneath the sea ice and ice shelf due to lower salinity water coming off the glacier and re-freezing quickly in the -1.9 degree Celsius water; it’s reminiscent of sheets of glass and just as strong. Soon after, Pete spots two cracks, one on either side of the hagglund, so we jump out and split into two teams, shoveling, measuring, and drilling out both of them to characterize them. We all get a turn with the drill (surprisingly fun) and the shovel (decidedly less so), and determine that while they are both quite wide (over a meter each), the ice under them at the thinnest point is over two meters, so we push forward.
Reaching the EGT is a relatively painless affair, other than all the bumping around we do – the Hagglunds, like many tracked vehicles here, have no suspension, so every bump in the ice is felt in your spine. We get out the Echo drill again and discover the ice is over three meters – the fourth flight didn’t fit – which is thicker than expected and plenty for our location. Out of curiosity, we drive further into the crook of the glacier tongue; we want to be as close as possible in order to go look at the grounding line under the ice, where the glacier flows off the land. Pete warns us to stay a few hundred feet off the glacier itself, or risk calving ice falling on our camp or near it. We find a suitable spot and drill holes for a set of flags; Pete marks the spot, and will later use the GPS marker and the flags to flag a route out here for us. In the meantime, we spend a few minutes before getting back in for what Pete describes as a “nature hike”.
I’ve been on many hikes across the world, and many of those were quite stunning and beautiful. But nothing quite compares to the half hour we spent on the foothills of Erebus. There’s a scene in Interstellar in which the expedition lands on the icy planet Mann and walks around for the first time; this is the closest analogue I can come up with for the sensation of this trek. (This is perhaps misleading, since the scene was actually shot in Iceland.) The ice is stunning, forming amazing structures of all shapes and sizes, with cracks and crevasses lurking under a half-meter of snow; pictures cannot do it justice. Pete leads us, coming into his own as he slips into mountaineering-guide-mode. This is his terrain, and he expertly leads us around ice spires and caves, and through a small ravine before reaching an outcropping from which we can go no further. The blue color of the ice is mesmerizing, like the color of a perfect sky, incredibly pure. Britney describes how the pressure from the glacier is so great that it literally squeezes all the bubbles out, making the ice incredibly clear – the blue is created that way. Pete discovers a small crevasse and pulls out this crazy looking ice that looks like salt crystals but so much clearer, which Britney tells us are called crevasse hoarfrost. They’re an unusual type of frost that grow in crevasses and are used to predict avalanches due to their fast growth and very weak structure. It’s an incredible landscape, and as turn around and make our way back across the snow and ice to the hagglund and back to the Rock, I can’t help but stare out the window in awe of the Ice.