Why things easily leave earths atmosphere but burn up while re-entering the same atmosphere
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When you lift a hammer it doesn’t make a hit, when you let it go down it does.
You use a massive rocket to push the thing up through the atmosphere, at a controlled, increasing speed.
Broadly, at re-entry, the vehicle needs to bleed the speed it accumulated in the way up, and the preferred method is by air friction. Now, you can’t really chose a shallow path as there’s much risk to bounce on the atmosphere and get back into space, then fall down again at a bad angle again. Instead, they chose the safest approach of going down sharp enough to pierce the atmosphere.
This comes at the expense of having quite rough minutes of very hot friction and other the atmosphere.
Once you lift the hammer, it has to impact something on the way down. The only way to prevent it is to put the hammer down gently, which in the space equivalent, would mean having a big rocket to slow you down before re-entry, which would require a lot of fuel, really a lot of fuel. And even more fuel at take off to carry up the extra load. Doable? Yea. Economic? Nope.
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