Dr Alun Hubbard from the university of Aberystwyth in Wales, UK, places a Geodetic GPS unit on the front of the Humboldt glacier. One of many techniques that glaciologists use to gain data about glacial dynamics and melt rate, the GPS units measure vertical displacement (the up and down movement caused by tidal variation) and horizontal velocity/ strain rates (caused by the pressure of ice upstream of the glacier). A pair of GPS (Trimble 5700s) are deployed, one 5 metres, the other 300 metres from the front. The data from the two GPS units, recorded in 10 second intervals, will help understand further the cause and response systems which trigger calving of glaciers on Greenland. Dropped off on the precarious face by helicopter, Hubbard drills 3 metre deep holes with a drill and ice auger, which take steel poles holding the GPS fast to the ice. Hubbard returns to collect them some weeks later.