In an astonishing feat of endurance, explorers Justin Packshaw and Jamie Facer Childs are a quarter of the way through a 3600-km kitesurf trek that takes them across the desolate heart of Antarctica. They are not pushing their physical and mental limits to the brink, facing howling gales and temperatures of –55°C just for the sake of adventure. They are gathering information to help scientists better understand how the body responds to extremes and taking unique measurements of their ice environment that will help complement ESA's CryoSat mission to better understand how this giant ice sheet is evolving in response to climate change.