The British Antarctic Survey has closed its Halley base for another winter.
The staff members left the station, leaving about 80% of the experiences they normally performed during the polar night and operating automatically.
The closure is a result of persistent uncertainty surrounding the stability of the ice near Halley, which is expected to soon break in the sea.
BAS believes that the base is far enough away to not be affected, but does not want people to be present in case.
The sending by plane to evacuate the personnel in dark weather and in winter time is an unnecessary risk.
It's the third winter on the trot now that Halley is closed.
The base rests on the Brunt Ice Shelf – the floating protrusion of glaciers that flow from the interior of Antarctica to the Weddell Sea.
Periodically, this platform will house icebergs and a large gulf will open that will create a particularly bulky block – about the size of Greater London.
But when that happens precisely, no one can say it.
"What really matters is what happens upstream of Halley's abyss," said Professor David Vaughan, BAS Scientific Director.
"We have a network of about 15 GPS stations on the ice floe that surrounds Halley, and their data is essentially transmitted to us every day with a day late, and even if, yes, at the limit, there are changes – from Halley, we actually saw very little deformation of the ice, "he told BBC News.
There has been a permanent research station on the Brunt since the late 1950s. The buildings have been modernized several times, the most recent installation including legs and skis. These make it possible to move the whole of the segmented structure.
In 2017, BAS tractors moved the base 23 km from the water's edge to place it in a safer place. It was a wise decision because without the relocation, Halley would now be on the wrong side of the abyss.
Glaciologists continue to use satellite images of the region to monitor the behavior of the abyss. The situation was somewhat complicated because of the appearance of an additional crack, called Halloween Crack, which flows in a different direction.
The course of events will largely depend on what happens in a shallow water area known as McDonald's Ice Rumples.
This hump at the bottom of the Weddell Sea serves as a point of attachment that holds and stabilizes the Brunt Plateau, a thickness of 150 m. The breaking point of the abyss – and it remains about 4.5 km – will certainly have an influence on the reaction of ice upstream.
Halley is extremely important for BAS's activities.
In addition to serving as a launching pad for forays into the depths of the Antarctic, it brings together essential weather and climate data.
He played a pivotal role in the research that helped identify the "hole" in the ozone layer in 1985. In recent years, it has also become a major center for the study of ozone. Solar activity and its effects on the Earth.
The investigators are working hard to maintain the observations even if they will not be present themselves.
A key element is the installation of a micro-turbine – a kind of "jet engine in a box". This provides automated instrumentation, including the Dobson Photospectrometer that monitors the ozone layer.
Doing experiments in Antarctica without going through men is a challenge because of the harsh conditions.
If the air intake of the micro-turbine hangs with snow or ice and there is no one around to remove the obstruction, the machine will turn off and the instruments will disconnect.
But the jet engine has been operating without incident for several weeks now, and Professor Vaughan believes that if the system is proven, it could become a very useful technology in other parts of Antarctica.
"We could use it on the ground in places where it is currently too difficult or too expensive to manage wintering stations," he said.
"Halley is a good test, it's not an easy place to exploit."
People will return to base when sunlight begins to return to the polar south around October / November.