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One extremely important consideration that goes into the engineering of spaceships is their ability to withstand the heat of reentry. Pushing through the Earth’s atmosphere causes extreme temperatures that can burn up manmade objects and space debris alike. What causes this fiery phenomenon?
1. It’s not about friction, and it’s not about height.
It’s logical to think that friction is the driving force behind all this heat, but in fact it only plays a role closer to the ground where the atmosphere is more dense. Higher up, where meteors streak across the sky and spacecraft return from missions, friction and altitude have very little to do with reentry burning.
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2. Velocity is the main factor.
If not friction and height, then what? The answer is velocity and compression. Incoming objects are moving at incredible speeds, and as they do they’re compressing the air in front of them. According to the gas laws of chemistry, compressing a gas heats it up, and there’s a whole lot of compressing going on during reentry. It’s this reaction that causes heat to be generated, and few things can stay intact in that heat unless we make them specifically for the purpose (or they’re way too big, like giant asteroids).
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3. This is why heat shields are so important.
NASA has beaten the heat with heat shields, which are designed to withstand the extremes they’re exposed to. Sadly, this doesn’t always avert tragedy. The Columbia space shuttle disaster was a result of a heat shield failure. The shield was damaged and upon reentry, the atmospheric gases broke the shuttle apart.