Reentry heating is primarily caused by hyper-velocity atmospheric compression (ram pressure), where air molecules in front of the vehicle are compressed so rapidly that temperatures soar up to 1600°C (3000°F) or more.

No, contrary to popular belief, air friction against the hull plays only a minor role; the intense heat is overwhelmingly generated by adiabatic compression of air molecules directly ahead of the spacecraft's shock wave.

Thermal protection systems utilize specialized materials such as silica ceramic tiles, carbon-carbon composites, or ablative heat shields that dissipate and radiate thermal energy away from the primary cabin structure.

Ablative shields absorb extreme heat by melting, vaporizing, and sloughing away in controlled layers, carrying thermal energy away from the spacecraft into the surrounding plasma wake.

As air molecules become superheated into a sheath of ionized plasma around the spacecraft, radio wave communications are completely blocked for several minutes until the vehicle decelerates.

Flight engineers must maintain a precise reentry corridor angle; entering too steeply causes catastrophic overheating and g-force overload, while entering too shallowly causes the spacecraft to bounce off the atmosphere.

Blunt shapes create a detached bow shock wave that stands off in front of the vehicle, pushing hot compressed gases away and ensuring most of the thermal energy bypasses the hull structure.

Noticeable aerodynamic heating typically begins around 120 kilometers (75 miles) above sea level, where the upper atmosphere starts becoming dense enough to slow orbital velocities.

A spacecraft traveling at orbital speeds possesses massive kinetic energy (E = 0.5 mv²), which must be entirely shed through atmospheric drag and converted into thermal and acoustic energy.

Molecules of nitrogen and oxygen dissociate and ionize into a glowing, highly reactive gas soup surrounding the vehicle, requiring specialized surface coatings to prevent chemical erosion of the heat shield.