I've been reading material about the Perlan II experimental glider. They hope to take it up to 90,000 feet -- higher even than an SR-71 BlackBird.
But the Perlan II is just a glider. Can it really just climb thermals up to that level? Is there something special about its aerodynamic design that lets it do that -- or are all gliders capable of climbing as high as possible, with only the heat and oxygen needs of the human occupants being the limiting factor? Or is it just me that finds it odd that a glider can climb higher than a powered aircraft?