A recent break-up of sea ice in the Lincoln Sea threatened to not only bring an abrupt end to a 2,000 kilometre Arctic Ocean trek, but also endangered the lives of the two Belgians attempting to complete the trek. But thanks to the European Space Agency (ESA) Envisat satellite, disaster was averted, and the two intrepid explorers are continuing on their way towards Greenland. The all-weather Advanced Synthetic Aperture Radar (ASAR) sensor and optical image data from the Medium Resolution Imaging Spectrometer (MERIS) are routinely analysed by Leif Toudal Pedersen from the Danish National Space Centre at the Danish Technical University. He interprets ice conditions and provides information on changes in these conditions. Dr Pedersen was able to use satellite images to guide the explorers away from the disintegrating ice, modifying their route. 'I noticed in satellite radar images that the Arctic Arc expedition was heading straight into very difficult and dangerous ice conditions, with large areas of thin ice and open water,' says Dr Pedersen. 'Luckily I was able to follow the changes in ice conditions and ice drift thanks to the daily coverage provided by the Envisat ASAR sensor [...]. Combined with [data] from the MERIS optical instrument, it helped me predict safe and unsafe areas in the sea ice.' Explorers Alain Hubert and Dixie Dansercoer are helping with the preparations for the CryoSat-2 mission while en route. They are measuring snow depths at regular intervals for scientists to assess how well snow conditions can be predicted using existing climate models. The joint EU-ESA Global Monitoring for Environment and Security (GMES) programme will provide scientists with even better tools to monitor ice conditions. GMES will support the implementation of public policies at European or national level that deal with, for example, agriculture, environment, fisheries, regional development, external relations and security.