Mid-Air Crisis

High in the mesosphere above the Grand Banks of Newfoundland, the *Valkyrie-One* was an incandescent sliver of light cutting through the edge of space. At eighty-five thousand feet, the atmosphere was a razor-thin shroud, offering almost no aerodynamic resistance. But in hypersonic flight, that same thin air could turn into a hammer of unimaginable violence if the delicate shockwave structure was disturbed. Astrid had spent years studying the phenomenon known…