Wikipedia has an Ivy Mike level nuke at 530 TPa, and the core pressure is at 380 GPa. That's a factor of over 1000 times. I'm wondering whether these are exactly comparable, since the pressure at the core is constant, whereas in a nuke, it's relatively brief. A multi walled carbon nanotube was tested with a tensile strength of 63 Gigapascals. Apparently, they have a theoretical upper limit of 300 GPa, so that's a bit short of surviving at the core. Is that a theoretical upper limit on strength full stop or just nanotubes? Then, there's the temperature which is similar to the surface of the sun at the core as well. Is there any hope of making a vehicle which could survive down there? I take it no material can survive within ten feet of a nuclear explosion though.