EarthThe white walker: Longest horse trek crosses icy lake See a re-enactment of a 17-year-old Cossack officer's ride across frozen Lake Baikal in 1889 – part of a 9000-kilometre journey through a Siberian winter Regulars
TechnologyIrrepressible robot roo bounces on flexible blades A robotic kangaroo controlled by an armband uses elastic springs to bounce just like the real thing Regulars