In 1962, the US government thought it might be a good idea to send a hydrogen bomb hundreds of miles into the air and detonate. Just, you know, to see what happened. Decades later, now you can too.
The recently declassified image was collected by Peter Kuran for his titillatingly titled documentary Nukes In Space. NPR has the full story here, but this is the juicy bit:
The plan was to send rockets hundreds of miles up, higher than the Earth's atmosphere, and then detonate nuclear weapons to see: a) If a bomb's radiation would make it harder to see what was up there (like incoming Russian missiles!); b) If an explosion would do any damage to objects nearby; c) If the Van Allen belts would move a blast down the bands to an earthly target (Moscow! for example); and - most peculiar - d) if a man-made explosion might "alter" the natural shape of the [Earth's magnetic]belts.