GPR Early Results

What was the radar experiment like in Antarctica 1997 season like? Well, since it was a component test, it was all mounted inside a small sled.

There are three areas with early results:

Buried Object Detection

The idea was to test the ability of the radar to detect rocks and buried objects covered by snow. To do that, a set of seven common Antarctic rocks and "meteowrongs" (rocks that look like meteorites, but are not) was covered by snow at known positions in a row. The radar was dragged over and over several times, with small displacements from the central line. The rocks have different sizes and compositions. Also, two transversal metal pipes at one side and one at the other marked the row position.

The figure shows raw radar data. The vertical axis corresponds to the depth of the soundings. The upper line is equivalent to the surface, the lower line corresponds to the deepest echoes recorded.. The horizontals axis corresponds to the advancement of the sled on the snow. The perturbations at both sides of the figure are the echoes of the marker pipes.

The seven objects lie between those markers. In this picture, there is one rock that shows clearly without further processing. The magnification shows a dark trace, echo of one of the rocks, and is indicated with a thick white arrow. It is possible to detect the other smaller rocks with careful examination of the data.

Of course the idea is to achieve automatic detection of buried objects, for the meteorobot to indicate and mark position of potential meteorites.

Layer Composition

Another goal was the demonstration of layer detection. The radar went over patches of snow over the ice. And that is what we can see in the next raw radar data. The arrows show when the sensor went over ice and snow. The snow patch is about 20 cm. thick. The other bands are radar noise.

Void and Crevasse Detection

For a machine that explores the vast ice fields of Antarctica, an important danger is to find crevasses, not always obvious given that they are covered by snow. These are cracks in the ice field that are wide and deep enough to swallow the rover. The detection of this features is one of the goals of radar sensing.  For that, test over small crevasses and voids were performed. The following figure shows radar data taken over a void.
The radar sensed a cave under a meter of ice and compacted snow. The raw data shows the change of the media (ice to air). At this point there is no automatic interpretation or detection of the voids and cracks. It is not even evident to the human eye. Crevasses appear in a similar way although the marks are thinner and vertical.

Once again, the two vertical marks signals at the left and right sides of the image are artificial markers that define the area of interest. The arrows show the void perturbation.

Back to Radar Experiment Results.

Robotic Search for Antarctic Meteorites 1998
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Send comments, questions, or suggestions to Dimitrios Apostolopoulos.
This document prepared by Michael Wagner.