During the 2007-08 summer field season 15 GPS receivers, recording position observations every 15 seconds for 24 hours a day, were successfully deployed over the Larsen C and Filchner-Ronne ice shelves. Six of these stations were uplifted at the end of the field season with the remaining stations left to operate over the 2008 Antarctic winter. Some had systems designed to power the instruments through the winter using either solar+wind or lithium batteries. The other sites only had solar power and would only run until the autumn, and then perhaps again in the spring. The 2008-9 field season was dedicated to retrieving the instrumentation.