Does it melt?
What is "it"?
The orbital ring's core structure is a continuous cable loop— a rotor made of high-tensile fiber (Zylon) that circles the entire Earth at 100 km altitude. It spins at 8 km/s, slightly faster than orbital velocity. That excess speed generates outward centrifugal force, which is what holds the ring's stationary platforms up against gravity — no rockets, no propellant.
Why does this question matter?
At 8 km/s, the cable is tearing through the thermosphere — the upper atmosphere isn't a vacuum. Air molecules slam into the cable and convert kinetic energy into heat. If the equilibrium temperature exceeds what the cable material can withstand, the entire orbital ring concept is dead. No ring, no tethers, no cheap access to orbit, no Dyson swarm. This is the first question that must be answered before anything else.
Drag the altitude slider and see for yourself.
Solar max increases thermospheric density ~10× due to UV heating and atmospheric expansion
Material Survival
Show equations
The answer
At 100 km altitude, atmospheric density is low enough that drag heating is just 2.56 W/m in solar minimum — easily radiated away as infrared. The cable reaches an equilibrium temperature of approximately -10°C. That's a 4.1× thermal margin against copper's melting point, and well within the operating range of Zylon, carbon fiber, and every other candidate material.
It does not melt. The concept survives its first existential test.
The hard constraint is altitude: below ~85 km, atmospheric density increases exponentially and drag heating becomes catastrophic. At 80 km it reaches ~51 kW/m — no known material survives. The rotor must stay above this floor.
Read the full analysis in the white paper →