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Robin McKie, science editor
British scientists have been given the go-ahead for a
project aimed at dropping a robot probe into a vast, subterranean
lake two miles below the Antarctic ice.
The aim is to study the microbes and other lifeforms found
in Lake Ellsworth in West Antarctica and to study sediments
on its floor. The latter could provide vital information
about climate change.
'We have no idea when the West Antarctic ice sheet last
melted completely,' said Professor Martin Siegert, of
Bristol University. 'But by studying these sediments we
should be able to work out if West Antarctica was completely
ice-free in the recent geological past, a few hundred
thousand years ago.
'Given the rate at which the planet is heating up, we
need to know just how vulnerable the West Antarctic ice
sheet is. If it melts completely, sea levels will rise
by six metres or more and drown great stretches of coastline
round the world.'
Lake Ellsworth is buried more than two miles beneath
the ice sheet and is one of 145 sub-glacial lakes that
have recently been pinpointed on the continent by airborne
radar surveys. Scientists now know that heat emanating
from Earth's core gently melts the base of the Antarctic
ice sheet and this produces vast caverns - many of them
dozens of miles in length - that have filled with water.
'In some cases, this water has lain undisturbed for millions
of years,' said Siegert, who is leading the Ellsworth
project, a multi-disciplinary team from 12 UK universities
and research centres. 'The lakes are therefore of incalculable
scientific importance - and not just for understanding
life on Earth. We now know that Europa, one of the moons
of Jupiter, is coated with a thick layer of ice that covers
a vast ocean and this could, possibly, provide a home
to alien lifeforms.
'However, if we want to go and look for these, as space
engineers are planning, we will first have to learn how
to explore ice-covered environments on Earth.'
And that will not be easy. Most of Antarctica's buried
lakes are found on the eastern half of the continent,
including its biggest - Lake Vostok. This was until recently
the favourite candidate for a drilling project, but the
logistical problems have proved daunting. The lake is
buried under 4km (2.5 miles) of ice.
Nor is it possible to use standard oil-drilling technology
to reach the lake. Kerosene, used as an anti-freeze, would
contaminate the pristine water below the ice. So they
aim to use hot-water drills: essentially huge shower heads
that spray out water at high temperature and pressure
and which would simply melt their way downwards.
'The trouble is that the ice above Lake Vostok is incredibly
cold - minus 60 Celsius - and that makes it difficult
to melt,' added Siegert. 'So we have picked Lake Ellsworth.'
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Guardian
Unlimited -
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