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Monday, 19 March, 2001, 14:38 GMT
Ice probe explores glacier's secrets
Ice Nasa
Inside a glacier, the ice probe makes its descent
By BBC News Online science editor Dr David Whitehouse

A probe that bored deep into an Antarctic glacier has revealed surprising details about the ice sheet's structure as well as the zone where the glacier grinds along the rock floor.

The ice probe plunged more than 1,200 metres (3,900 feet) down four boreholes drilled in the West Antarctic ice sheet.

It found rivers flowing beneath the ice as well as evidence that rocky debris picked up from the floor travels further through the glacier than had been thought.

It is hoped that the probe will pave the way for technology capable of exploring other extreme environments on Earth as well as those on other planets, especially Jupiter's ice-crusted moon, Europa.

Treasure trove

Scientists say the West Antarctic ice sheet contains a treasure trove of information related to the geological history of the White Continent and the way ice flows from it to the oceans.

Ice Nasa
Layers were seen in the ice
Previous studies show that significant changes in glacier melting and flow rates could have a considerable impact on global sea levels.

The investigation took place at Ice Stream C, an area where 150 years ago the ice suddenly stopped flowing in one particular area.

This so-called "sticky spot" currently flows at a rate of 2 m per year (6 ft), much slower than the neighbouring ice streams which flow at about 400 m (1,300 ft) per year.

Surprise findings

Descending into the glacier with two cameras and lights, the probe revealed a water system at the bottom of the ice. In places, there was a water-filled cavity measuring approximately 1.4 m deep (4.6 ft).

Ice Nasa
Lowering the ice probe
To the researchers' surprise, they also found rock and other debris embedded in the ice much higher than expected.

It was believed that debris in the ice would be found no higher than 2 m (7 ft) above the base of the ice stream. However, the measurements made by the ice probe show debris some 26 m (85 ft) off the base.

The probe also detected layers in the ice. It is thought ice and gravel is frozen on to the base of the ice sheet and this is then lifted as more water slides underneath and solidifies.

Search for life

"The layered information will turn out to be very interesting," said project director Frank Carsey of the American space agency's (Nasa) Jet Propulsion Laboratory.

By analysing these ice layers, researchers may learn how ice streams flow, change direction and sometimes stop flowing altogether. Eventually, biological sensors may be added to the probe to search for evidence of life in the Antarctic ice sheet.

Microbes are known to reside under mountain glaciers, where it is warmer and there are nutrients from impurities found between water crystals.

The sensors on the ice probe could be the forerunner of probes designed to look for life on Mars and elsewhere in our Solar System.

"This project fits into the bigger picture of planetary studies," said Carsey. "It provides us with some understanding of how to observe what goes on in ice caps - Earth's ice caps, Martian ice caps and ice caps on Europa."

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See also:

01 Feb 01 | Sci/Tech
Antarctic ice sheet shrinks
20 Oct 99 | Sci/Tech
Falklands on alert for giant berg
25 Aug 00 | Sci/Tech
Waterworld on Europa?
26 Jun 98 | Sci/Tech
'Ice bacteria' clue to life on Mars
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