As you may already know, this season marks the start of the project to relocate Halley VI station 24 km east of its current position due to a crack which started opening up in the Brunt Ice Shelf in 2013-2014. In this post, I’ll share some of the pictures taken while the first half of buildings and modules have been moved, as well as give you some detail about the project itself.
The Brunt Ice Shelf
Halley Research Station has been located on the Brunt Ice Shelf from 1956, when the first iteration of the base was initially established. As of 2012, a sixth incarnation of the Halley Station is in operation – the previous five having been buried in snow and ice or decommissioned, demolished and shipped out.
To quickly help with the terminology, Antarctic Continent is covered by the Ice Sheet (sometimes referred to as continental or glacier ice). The ice sheet is continuously pushed out towards the ocean due to its weight and the shape of the Antarctic Continent. Once the ice flows off the land and floats on the water, it becomes the Ice Shelf – and the zone where this happens is called the Hinge Zone (as Ice Shelf hinges there with the tides). The Ice Shelf is a thick slab of ice – in case of the Brunt Ice Shelf, it’s estimated its thickness is around 350m near the Hinge Zone, and between 150 and 200m at the coast. For completeness, there’s also Sea Ice, which is a frozen sea water and which can be attached to the edge of the ice shelf, but this ice is much thinner and the mechanism of its creation is completely different.
Having the research station built on the Ice Shelf means contending with some of the unusual properties of the environment. One of these is that the Brunt Ice Shelf is constantly moving in the westerly direction, being slowly pushed out to the sea by the masses of ice flowing off the Antarctic Continent. The current rate of movement where Halley VI is located is 1.3m per day or about 450m per year. This means that even though we don’t notice that, we’re constantly on the move. It also means that the Brunt Ice Shelf is constantly changing.
To the South East of the station are two large features called Chasms. These are ancient cracks in the ice, which filled with snow and froze over over hundreds of years. Now they look like very shallow canyons or valleys and it’s possible to abseil or even drive a skidoo into them, depending on the terrain around.
One of those chasms, after having been dormant since the records started, has recently started opening up and the tip of its crack is now moving in the northerly direction. If the station was left alone, in several years the crack would appear between the station and the land. This would create a risk of the part of the ice shelf Halley VI is located on to calve off, taking the base with it.
Where are we moving to?
To avoid the issues described above, a decision was made to relocate the Halley VI station to a new site, on the “safe” side of the crack before the tip of it moves too far north to make the move more complicated. Several prospective sites were looked at and surveyed and a final decision was made to pick a site 24 km due east of the current location. A number of parameters and requirements were taken into consideration when choosing the new site, some of which include:
- The topography of the new site – ideally the new site should be flat with no big bumps or undulations
- Distance from cracks and other features
- Existence of a safe route, suitable for towing large modules between the two sites
- Distance and availability of a route from the new site to the coast for future relief operations
The new site, as well as the route in between, have been thoroughly surveyed by field guides and glaciologists, using GPS and Ground Penetrating Radar, to ensure their suitability and stability.
What is involved in the move?
After the new site has been chosen, surveyed and approved, the station needs to be prepared for the move. The Halley Relocation Project’s goals are to move the station in two stages over two consecutive summer seasons, while maintaining continuous science output of the station as much as possible. This adds a bit of complexity to the move, but should limit the impact on the science, which is the main reason for existence of any Antarctic research station.
This summer the move will include all accommodation buildings (the main modules as well as the Drewry building, which is the summer accommodation block), the garage, the communications array (HF and Satellite antennas) and the skiway, as well as most storage containers and fuel. All science infrastructure will stay at the current Halley VI site, however, for the coming winter and will be relocated next summer.
To allow for this two stage move, the WASP (Workshop and Storage Platform) has been partially converted into a living area (with a couple of bedrooms and a communal space). In addition, a science accommodation and office cabooses, as well as a new generators caboose have been put in place. All this, together with the currently existing science cabooses (C1, C2, C3, C4, C5, C6 and CASLab) constitute what’s called the Winter Science Camp. The Winter Science Camp is now also connected with a wireless microwave link to the new Halley VI site to provide data and phone services between the two.
Additionally (and this was my main project, which took up pretty much all of my time in winter), a new Data Management server was installed in the C2 Caboose – this will be used to collect and process the data from all experiments.
After all this preparatory work was finished, it was time to prepare the modules for the move. The following is a massive simplification of the work involved but gives a good overview of the process.
The first task was building the Temporary Camp, which took the form of a container/tent city. This camp is fully independent of the main station, with its own kitchen, bathrooms and toilet facilities, melt tank, bedrooms and a large-ish mess tent. There are a number of additional cabooses and tents around it to sleep more people. When all this was ready, everyone moved out of the modules to their new accommodation and the modules have been powered down. Next, all services have been drained (so there’s no water or other fluids in pipes and tanks) and everything secured for transport as much as possible. Finally the modules have been disconnected from each other and all cabling and hoses running between them removed.
In the mean time, the Vehicles Team used their time preparing a road way between the two sites. This required several dozens of passes along the route with grooming machines to make the surface firm and smooth enough to take very heavy loads.
The first building to move across to the new site was the garage. To ensure enough pull to cope with the weight and friction, six vehicles were used to tow it in sets of threes: two John Deere tractors leading the pack, then two Pisten Bullies followed by two Caterpillar D6 bulldozers. Each vehicle in the set was connected with a tow cable to the vehicle in front. The dozers were also connected to the Garage using their tow cables on their winches. In addition, two extra dozers were used for the initial push of the garage to break the tension.
One of the new features introduced this season is the use of the load measuring shackles. These are equipped with an electronic sensor and measure the load (reported in tonnes) applied to the tow cable. This allows the vehicle team to gather the data which can then be used to better plan how many and what type of vehicles to use for towing the modules.
After the garage move came the BAS Ship, RRS Ernest Shackleton, so the station switched to the relief operation – we wanted to unload all cargo and fuel from the ship as quickly as possible, so we could get back on to the move. The relief was finished in 10 days and the Shack set sail a few days before the New Year.
Then, after a short break to take some rest, we moved the first module: H2, which is the southernmost one and which is where the Upper Obs, Lower Obs, Electronics Lab, Light Mech Workshop and the Server Room are located in. To move the module it has to first be lowered down on its hydraulic legs. In addition, special steel braces have to be installed between all legs to brace them together for transport, as well as special low friction matting placed underneath the skids. Finally the H2 Module was nudged forward a few centimetres to separate it completely from its neighbour and the rest of the station. All this work has been done actually before the garage move, as we anticipated moving that module earlier, but as is usually the case, the weather had other plans for us.
After the H2 Module was towed successfully to the new site it was the H1 Module’s turn. The station works in 24 hour mode during the move, and each module is prepped for move during the day and is being towed at night by the night shift – this is to take advantage of lower temperatures resulting in firmer ground. Finally, the following day the vehicles are being sent back and the next module is being prepared. Both modules were towed by a set of three vehicles: a Pisten Bully and two Caterpillar D6 dozers, all linked up with tow cables.
Following the move of the H1 Module it was turn to move the Drewry building along with all of its 32 occupants. This again required a number of vehicles in a similar configuration as for the move of the garage: two John Deeres, two Pisten Bullies and two D6 dozers. Adding to the complication was the fact that the Drewry was sitting in a sort of a pit, which formed when the snow collected and built up around it over winter. The building had to first be moved out of the hole before it could be towed, and this was done by using the vehicles as “anchors” and pulling the building out with the dozers’ winches.
After the Drewry got to the new site it was time to move the E2 module. Again, an added complication was the fact that the Link Bridge between E1 and E2 modules is literally supported by those modules, as it has no legs or pillars of its own. The estimated weight of the bridge was in the region of 18 tonnes and two Sennebogen cranes were used to support the bridge’s weight. Once suspended from the cranes, the E2 module was pulled away to make room for lowering the bridge. Then the cranes “swung” to the right, pulling the bridge out of its bearing in the E1 module and then lowered it onto the set of skids manufactured for the transport. Finally a Pisten Bully towed the bridge, with the E2 module having followed suit towed by a standard set of two dozers and a Pisten Bully.
Finally, last night, the E1 module was towed away to the new site, again using the standard set of vehicles. As of this morning, what’s left at the old Halley VI site waiting to be moved is the Big Red (main module), the C module and two bedroom modules (B1 and B2). All these will be moved to the new site in the next couple of weeks, weather permitting. The Science Infrastructure will stay here for the winter, and the Temporary Camp will be taken down.
What’s happening next?
When all modules are moved to the new site, they will have to be carefully positioned at their final place and connected together. The Tech Services team will then enter the modules and start their work on recommissioning them, enabling all electrics, hydraulics, heating and air handling, generators and all other services. When this is finished, the kitchen and accommodation areas will be relaunched, the IT and science infrastructure will be recommissioned, the new Wintering team will move in to the modules and everything will be prepared for the winter. Shortly after that all summer staff will ship out, back to the UK or other parts of the Real World.
That’s the plan, at least. Stay tuned for more!