Acoustic tool tested before polar research

Evaluating geological research equipment in snow before it is taken to the Antarctic are (from...
Evaluating geological research equipment in snow before it is taken to the Antarctic are (from left) University of Otago student Laurine van Haastrecht, university engineer Jim Woods, Southern Hemisphere Proving Ground operator Russell Scott, university geologist Christian Ohneiser and university surveyor Greg Leonard. Photo supplied.
Many new vehicles have been tested at Cardrona's Southern Hemisphere Proving Grounds but, until Saturday, they have moved on wheels, not skis.

The snow worthiness of geological research equipment built at the University of Otago was tested at the proving grounds, before it is flown to the Antarctic to be used in research work later this year.

University geologist Christian Ohneiser said the equipment would be towed 350km across the Ross Ice Shelf to an area believed not to have been visited, to research the sea floor beneath the shelf.

''It's very exciting. It's like we're going back to the good old days of exploring Antarctica.''

The equipment, called a thumper, thumps the ice, creating soundwaves which are recorded to help scientists determine what is underneath. The ice shelf, the size of France, is about 300m thick and floats on a part of the Southern Ocean which is about 400m deep, near Ross Island.

The thumper is the largest built in New Zealand and drops a 250kg weight.

Built mainly to research faultlines, it has been used on the West Coast and at Middlemarch and, this week, will be used in south Dunedin.

This is, as far as Dr Ohneiser is aware, the first time a thumper has been put on skis. National Geographic film makers, producing programmes about scientists at Scott Base, are accompanying researchers on Antarctic expeditions.

The thumper is, essentially, a modified fence post rammer on a specially built trailer with hydraulic equipment and a generator. Specially made metal skis have a Teflon like base and are attached under the trailer tyres.

The trailer is pulled by a vehicle similar to a snowcat and a 400m long string of 96 microphones, called geophones, is pulled behind to capture the soundwaves after each thump.

Dr Ohneiser, the expedition's science and logistics manager, said the information would ultimately be used to determine the vulnerability of the Ross Ice Shelf to climate change.

The information provided by the thumper would be used to find a place to melt a hole through the ice to take samples of the sea floor.

''Thumping'' in the Antarctic is the brainchild of the university's school of surveying dean, and expedition leader, Prof Christina Hulbe.

By Jessica Maddock. 


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