Sunday, February 6, 2000

SOARing to new depths

Published in the Antarctic Sun

A small team of researchers is painting the white-on-white landscape of Antarctica in bright colors. The Support Office for Aerogeophysical Research, headed by Don Blankenship of the University of Texas at Austin, is looking at the continent in ways many scientists have only imagined.

SOAR is a consortium of researchers looking at how ice and rock interact in Antarctica. Their maps are in full color, showing different types of rocks and land formations, often over a mile under the ice sheet.

The researchers fly in a Twin Otter airplane over swaths of area larger than the state of Maine, to look at the ice-flow systems in key regions of the continent.

“We’re trying to figure out how geology influenced the formation of the ice sheets,” Blankenship said.

The airplane is crammed with electronics, so many that it takes two to three weeks to configure properly.

That’s after the plane’s structure was so radically modified that it required its own certification from Canada’s Ministry of Transport before Kenn Borek Air was allowed to fly it.

“The airplane was put together to do both geology and glaciology projects at once,” Blankenship said. In addition to the internal instrumentation, it has antennas hanging off the wings.

The electronics are all sophisticated sensors, measuring the plane’s height above the ice, using ice-penetrating radar to look at the rock beneath the ice, and also measuring the strength of the
gravity and magnetic pull of the rocks.

The gravity of the rocks, when separated from the influence of the Earth’s pull, shows how dense the rock is, giving clues to its composition. When that is combined with information about the
rock’s magnetic properties, the type of rock can be identified quite accurately.

Putting all this information together into a meaningful picture, Blankenship said, requires an additional layer of sophisticated equipment and calculation.

The airplane has several GPS units onboard, which measure the position of the plane to within four inches.

With that data, and the results from the instruments, Blankenship and his team create incredibly accurate maps of the ice and the surface beneath the ice sheets covering Antarctica.

“We’re good to within 10 centimeters,” Blankenship said.

They can find sediments, holes, changes in ice-sheet layering, and other phenomena. The SOAR team helps teams like ITASE choose routes for traverses, sites for ice-coring, and helps predict how what they find relates to other locations around the continent.

Their radar also lets them see significant layers in the ice sheet.

“It’s essentially virtual ice coring,” Blankenship said. The next actual deepcore site in West Antarctica will be chosen by the SOAR team, in collaboration with the ITASE researchers.

This season they made several excursions, one completing work they have been preparing for since 1992.

The plane and equipment flew routes over the transition from the Ross Sea to the Transantarctic Mountains, across the mountains to the Wilkes Basin and all the way to Aurora Highlands.

This cross-section of an area of the continent about which little is known geophysically was very important.

“We can get a really good handle on the evolution of the whole area,” Blankenship said.

The planning and organization resulted in use of several locations for this research and other work this season: McMurdo, Dome C, Mid C, Byrd and Siple Dome camps were all bases for SOAR flights.

For eight years the project has been underway to help explain why the Transantarctic Mountains are where they are. But once it’s all set, things move quickly.

“It took, what, 15 days to do,” Blankenship said. Good flying weather and few equipment difficulties were part of the success, as was increased computing power.

After a four-hour flight, the plane and equipment need about 90 minutes to refuel and recalibrate instruments. During that time, the researchers can take a provisional look at their data and get a sense of how reliable it is. Even just a few years ago, researchers needed more than five hours to do the same task.

“The quality of the data we get is really outstanding for the remoteness of the environment,” Blankenship said.

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