1959 ... 9 megaton Titan warhead!

 .... this is what the 10 foot tall 'payload' of a Titan II looks like after it has plowed back through the lower oceans of atmosphere, at 15,000 mph, on it's course from outer-space to target. 

In the late 1950's, bigger and more reliable rockets brought both manned space flight and nuclear tipped Intercontinental Ballistic Missiles (ICBMs) toward imminent reality. Still unresolved were materials and shapes that could survive the furnace heat of 're-entry' back to Earth.

The problem was that no matter how streamlined the shape, or how super-duper the construction of the missile 'nose-cone', it came back to Earth a charred mess. To complicate the situation, on good days the rocket would be carrying an astronaut; on bad days a complicated machine of mass-destruction. Both still had to be in working order at the end of their flight. Threatening to lob large chunks of burned up rocket at your enemies was not an effective nuclear-deterrent!

The solution was two-fold and unconventional. Instead of a pointy tip to produce minimum atmospheric drag and friction heating, a blunt shape was adopted. The blunt shape produced a large 'shock-wave' in front of the nose-cone, pushing much of the air and heat out and ahead of the re-entry vehicle.

The second part of the solution was to allow the nosecone to burn! The blunted shape was covered in layers of heat resistant material [phenolic epoxy resin coated fiberglass]. This gluey glop, slowly, stubbornly charred and sloughed off layer by layer. It carried away the unbearable heat and lasted just long enough to allow the hydrogen bomb, or astronaut, to remain 'functional'.

( It should be noted that in the case of astronauts, the 'capsule' design turned the re-entry configuration 180 degrees around, with the most blunt rear end 'heat-shield' toward the descent and friction. The layering of burn away material was also much thicker since a human being was more fragile than a vacuum-tube powered Hydrogen Bomb.)

more info- W-53 Hydrogen bomb 

- The 9 megaton W-53 Hydrogen bomb was one of the USA's 'super-economy size' weapons. The early ICBMs were not very accurate and so military thinking was to wipe-out everything even close to the target.

original image of Mk-6 re-entry vehicle courtesy of The Smithsonian Institution