Of all the places inhabited by humans, life hangs by the thinnest thread in the Antarctic. Sea ice retreats enough to allow supply ships near the shore for only 12 weeks each year, leaving the small scientific colonies eking out an existence in the desert of ice and snow isolated and self-reliant for nine months at a stretch.
'Take it all in all, I do not believe anybody on earth has a worse time than an Emperor penguin, ' Antarctic explorer and biologist Apsley Cherry-Garrard wrote in 1922, sympathising with the continent's only permanent residents.
Summer temperatures range between -15infinityC and a frigid zero.
Winters reach -56infinityC. 'It's an incredibly harsh environment. In winter, if you go outside at all, it's for an hour at most. More than that and you're in danger of freezing to death, ' says British Antarctic Survey (BAS) project manager Karl Tuplin.
It is in this hostile environment that, from December, Tuplin will face the challenge of constructing BAS's new research station, Halley VI.
Halley VI will consist of six modules: two pods housing science laboratories; two energy generation pods; a large command, communications and living pod containing the station's canteen and recreational facilities; and an accommodation pod for the station's year-round maintenance and scientic crew.
All bar the living pod will have the same dimensions of just under 20m long and 10m wide, and share the same construction.
'Each module can be detached from the rest, stripped and recongured, providing a lot of exibility in the station's resources and conguration, as science programmes, stafng levels and changing technologies dictate, ' says Tuplin.
And the entire station has been designed to be jacked up and slid to new locations on skis (see box). This is vital as the chunks of the Brunt ice shelf on which the station will be located can snap off and oat away.
Structurally, each pod will be built up from a prefabricated steel space frame. Ski-mounted, hydraulically controlled telescopic legs will be bolted on.
Services will be run through the space frame before a deck of 200mm thick structural insulated panels, consisting of a GRP-foam sandwich, is laid.
Steel portal frames will be erected to support wall and roof panels, but before they are installed prefabricated bedroom and bathroom capsules will be slotted into place. GRP foam sandwich cladding panels with pre-installed triple-glazed windows will then be bolted to the portal frames. Gaskets and doors will make the pod weathertight.
'Immense effort has gone into achieving two primary goals ? making the components of Halley VI light enough to transport by sledge to the construction site, and ensuring that we can build all of the capsules and seal them from the elements within our 12-week construction window, ' explains John Hammerton, international director of Morrison Construction, which will be building the new station.
'Our working season runs from mid-December to mid-March, but we'll start preparing for the onset of winter on 20 February. As soon as the sea ice starts forming the ship has to set sail or we're stuck in Antarctica for the winter, ' adds Hammerton. 'By the time we leave the capsules have to be capable of withstanding the winter. If there's a chink anywhere, spindrift will get in, which means things have to be airtight.' Faced with a do-or-die schedule, Hammerton says construction will be tackled on a production line basis. As well as bathrooms and bedrooms, mechanical and electrical plant, pipeline and cable runs and hydraulic control systems are being prefabricated, allowing them to be plugged into place 'like cassettes'. All of these components are being produced in the UK. The structural frame and envelope, meanwhile, are being fabricated and tested in Cape Town, South Africa.
Once legs and skis are attached it will be possible to slide the pods forward in a line past a crane which will lift all of the prefabricated modules into place.
All connections will be bolted for speed but, Hammerton notes: 'It's just about impossible to handle M5 bolts while wearing double gloves in sub-zero temperatures, so there's a minimum bolt size of 16mm diameter, and where possible bolts are above 20mm.' Workers will be given special instruction on working in Arctic conditions.
'If you put tools down they'll melt into the snow and disappear within an hour, ' Tuplin explains.
Construction workers will also have to watch out for construction waste. Packaging will be minimised, but as an internationally protected wilderness, allowing polythene bags to be whipped away by the wind won't be acceptable.
Hammerton adds that Antarctica's unpredictable weather adds signicant health and safety risks. Despite the cold, Antarctic air is very dry, meaning that with the sun shining it is often possible to work in a T-shirt. But, he says, 'because of the hole in the ozone you burn in minutes, not hours'. And in Antarctica's frequent storms, visibility can be reduced to inches in minutes, increasing the risk of getting lost, while wind chill sends air temperatures plummeting.
Morrison returns to the Brunt Ice Shelf in December 2008 for a second 12-week season to connect the station's services.
Final t out and decoration takes place from December 2009 to March 2010, alongside the demolition of Halley V.
Client: British Antarctic Survey Structural and M&E engineer: Faber Maunsell Architect: Hough Broughton Main contractor: Morrison Construction External envelope fabricator: AMCC consortium, Cape Town (cladding and glazing by MMS, space frame by Petrel and fabrication engineering by Toutite) Construction cost: $43.5M Budget (including transport and logistics): $75M