Susuto

While Uclc’s response is reasonably accurate, it misses a couple of points. First of all most of the heat experienced in re-entry is the result of using aero braking to decelerate from orbital, or even extra-orbital velocities to landing velocities.

When the shuttle returns from a mission to the space station, it is changing from an orbit of approximately 340 Kilometers above the surface to the surface. The period of a station orbit is approximately 91 min (this varies by it’s actual altitude.) Ad the altitude to the diamater of the earth (~6738 km) and you end up with a orbital radius of ~7100 km. Multiply by 2 pi and you get the orbital circumference. Multiply by 2/3, and you get an orbital velocity of more than 29 thousand kph. That gets dropped to about 360 kph, mostly by converting velocity into heat. Soyuz capsules also loose the 360 for a relative zero ground speed.

Kittenger was not travelling at orbital velocities. With the exception of the velocities that the balloon may have collected while passing through a jet stream, he was travelling with effectively zero ground speed. (especially in comparison to orbital velocities. As a result the only speed he needed to be concerned with was terminal velocity through the atmosphere he was in, which at 30 miles is a speed about the speed of sound.