British scientists who were attempting to drill beneath Antarctica in a search for undiscovered life have called off their mission.
A Bristol University team was trying to drill through 3km of ice to reach the water and mud underneath Lake Ellsworth.
But late on Christmas Eve the decision was taken to stop as the team was unable to form properly the water-filled cavity 300m beneath the ice.
This cavity was to link the main borehole with a secondary borehole used to re-circulate drilling water back to the surface.
Professor Martin Siegert, who was leading the team, said: "Although circumstances have not worked out as we would have wished, I am confident that through the huge efforts of the field team, and our colleagues in the UK, we have done as much as we possibly could have done, and I sincerely thank them all.
"I am also hugely grateful to the UK Natural Environment Research Council for making it possible for us to attempt the direct exploration of subglacial Antarctica.
"Sixteen years ago, we hypothesised that deep-water subglacial lakes are viable habitats for life, and contain important records of ice and climate history.
"For now, these hypotheses remain untested. Once back in the UK I will gather our consortium to seek ways in which our research efforts may continue.
"I remain confident that we will unlock the secrets of Lake Ellsworth in coming seasons."
The team have not yet discovered why they could not establish a link between the two boreholes, despite trying for more than 20 hours.
During this process, hot water seeped into the porous surface layers of ice and was lost.
The team attempted to replenish this water loss by digging and melting more snow, but their efforts could not compensate.
The additional time taken to attempt to establish the cavity link significantly depleted the fuel stocks to such a level as to render the remaining operation unviable.
Reluctantly the team had no option but to discontinue the program for this season.
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