Alan Hubbard, a glaciologist from the University of Wales, Aberystwyth, is working on the Petermann glacier. He is installing 'expendable GPS' units, known as 'stations', attaching them to the glacier's surface. These self powered units communicate with a base station, so if they are lost or damaged at sea or during break up, the data has already been transferred. Alan has fixed three of these to the ice; one intended for each segment, known as A, B and C in order of expected break up. The data from the three units will tell the scientists, if after pieces have broken away from the glacier, whether the upstream part that is left behind will accelerate. To give an idea of scale, ice island 'A' is estimated to be of 100 square Km and the front of the glacier is 16km across.