Flying to the Larsen Ice Shelf

Cape Framnes

The bare rock of Cape Framnes, just on the edge of the sea-ice covered Weddell Sea.

It seems to be a long time since I last wrote a blog entry. This is because the start of the summer is a hectic time for the comms team, who work hard to keep up with all of the BAS planes inputting scientists into their remote field-camps, restocking fuel depots and collecting passengers from South America to bring into Rothera. However, things have now quietened down enough that I managed to find my way onto a flight heading over to the far side of the Antarctic Peninsula, a treat for me as I had only ever been on flights to our summer-only bases at Fossil Bluff and Sky-Blu in the past.

GPS transmitter

The Cape Framnes GPS transmitter.

The purpose of the trip was to go and service a pair of automatic GPS systems, which were put in place a couple of years ago by by the American National Science Foundation. These systems are scattered liberally over Antarctica, with some of them used to track the movement of ice-sheets, and others used to monitor something called isostatic rebound. This is a phenomenon which results from the last ice-age, when Antarctica was covered with vastly more snow and ice than it is now, in quantities that were enough to squash down the

Flying

Flying over the Antarctica Peninsula, with pilot Ian.

tectonic plate beneath. Now, 10,000 years down the line, the weight of ice is much reduced and the bedrock is springing back into place at a rate that can be measured with a very accurate GPS system. This both keeps the geologists entertained and allows me to go on some excellent flying adventures!

We took off from Rothera first thing in the morning, with the sun shining and barely a cloud in the sky. Our first destination was a desolate outcrop of rock called Cape Framnes. This sits at the very end of the long, winding Jason Peninsula, which itself forms the northern boundary of the vast Larsen Ice Shelf. We climbed to around 11,000 feet, enough height to get us over the lofty plateau which forms the middle of the Antarctic Peninsula. Needless to say, the remote mountains of the interior were vast, bleak and unimaginably beautiful.

Roger and Terry starting work on the GPS servicing.

Roger and Terry starting work on the GPS servicing.

A couple of hours later, the rocky Cape came into view and we circled it a few times as Ian, our pilot, attempted to find a smoothish patch of snow on which he could safely land the ski-equipped Otter on. This was easier said than done, as the whole hilltop was a maze of crevasses and sastrugi. He eventually picked a hopeful looking site a couple of kilometres away and executed a ‘trail skis’ manoeuvre, an exciting experience that is unique to polar aviation. The idea is to fly the plane along at ground-level for a few hundred metres, with the nose still in the air but the main skis just touching the ground with enough pressure to collapse any crevasse snow-bridges that may lie hidden under the surface. If the snow does give way, then hopefully the wings provide enough lift to carry the plan safely over. At the end of the trail-skis manoeuvre, the pilot cranks up the engines and gets airborne again, before circling round at low-level to examine the ski-trails for any gaping holes. Once he is satisfied that the location is safe, he can circle again to land. Eventually we touched down safely, with the little plane bucking and rolling as it bounced over the rough surface.

The last nunatak. Beyond this is the vast Larsen Ice Shelf.

The last nunatak. Beyond this is the vast Larsen Ice Shelf.

This left the small matter of a couple of kilometres of heavily crevassed ground to cross, so Terry (the American scientist responsible for the project), Roger (the Field Assistant) and I roped up, strapped on crampons, filled up our backpacks with the heavy tools and spares required for the servicing job and set off. Within about a minute of leaving the plane, Terry had found his first crevasse – one of his legs disappeared through an innocent-looking patch of snow and waved around in the void beneath as he clambered free. A few minutes later he found his second, a slightly larger one into which both of his legs disappeared. As he freed himself this time he made the mistake of looking down through the hole he’d made in the snow bridge and was horrified by the size of chasm which he had just visited. Fortunately, from that point onwards (and much to Terry’s relief) the crevasses became more obvious, so we managed to avoid them successfully.

Blue ice

Crossing crevassed blue-ice on the way to the GPS transmitter.

We eventually reached the rocky outcrop that was home to the GPS. It was a bleak spot, but stunning. The surface of the rock had been battered by the rampaging ice and freeze/thaw erosion, and resembled a sandy-coloured, neatly pebbled gravel drive. Out to the east was the vast Weddell Sea, still covered in sea-ice, but with the occasional black dot – seals that had survived the winter by keeping a hole in the ice open. To the south was the Larsen Ice Shelf, an endless expanse of white nothingness.

The malfunctioning GPS was marked out by a couple of large solar-panels, with a large plastic enclosure underneath. A keen 15 knot wind blowing off the ice-shelf was enough to encourage us to get moving, so we opened up the enclosure and Terry got to work. It took a few hours of tinkering, but he eventually announced success after replacing a few parts with the spares we’d carried in. The final step was for him to call up his office in the States on a sat-phone and confirm that they were receiving live data from the system. By this time the chilly wind had penetrated even our thick down jackets, so we were more than happy to rope up again and walk back to the plane. Once there, we greeted the pilot who immediately broke the news that Rothera had called him up on the sat-phone to alert us that, since leaving the site, the system had gone wrong again.

Rock outcrop

Terry and Roger getting kitted out on the edge of the rock outcrop.

We sighed, had a warming cup of tea and then set off again. This time we had the luxury of some footprints to follow, so managed to avoid any further crevasse-falls. Once back at the site, Terry wiggled a few cables and poked a couple of instruments with a screwdriver, and everything sprang back into life.

Back at the plane, the next step was to fly the short hop over to one of the nearby field-camps to drop off some equipment. The lucky field team had found an amazing spot for a campsite, on a glacier ringed on three sides by mountains, with a view out over the ice-shelf. However, time was ticking on and we were keen to get our next site, so we unloaded the cargo and were airborne again in minutes.

The sun was low in the sky by the time we reached the Leppard Glacier, another epic expanse of flat-white, ringed by mountains. Despite having the exact coordinates of the GPS that we were searching for, Ian had to circle a few times before any of us spotted it. Once we’d tracked it down, a tiny black dot in the middle of nowhere, Ian executed the mandatory trail-skis procedure again, landed and we got to work.

Icebergs

Icebergs calving off on the edge of the Larsen Ice Shelf.

It immediately became clear that this was an area of high snow deposition. An old photo of the site that Terry had with him showed the solar panels to be mounted on poles that were a good two metres high. However, they were now only just clear of the snow, so we wearily collected shovels and started to dig. And dig. And dig. By the time the clock had ticked round to 11:30pm, we had a hole in the snow that was considerably deeper than my 6ft 1inch, and were chipping through solid ice without having yet found a trace of the box.

Field camp

Not a bad place to camp. The field-camp overlooking the Larsen Ice Shelf, with tents and skiway.

I hate to admit defeat on a digging task, but by the time the sun had sunk below the horizon we agreed that there was no way to get to the box with the equipment that we had. To stand any chance of success a team would have to come back with pick-axes, motorised snow-blowers, and crucially, a primus for making tea. So we threw in the towel and headed back to Rothera, finally touching down after a long, superb day just after 1am.

The last task was to stow the plane in the hangar and unload all of the gear. It was only after setting off in the twilight to walk back up to the dining room that I discovered that an enormous elephant seal, our first of the season, had parked himself in the middle of the path and was grunting enthusiastically at anyone trying to get past. Tired as I was, I grunted back at him and headed to bed for some well-earned rest.

Twin Otter.

Twin otter delivering equipment to a field camp.

Crevasses

Incredible crevassing on the edge of the Larsen.

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