eli5: Why is the Kessler effect so dangerous? Won’t the space junk eventually fall out of orbit or drift off into space?

Question

I saw the opening of *Gravity* and it was pretty terrifying, but to quote Billy Bob Thornton in *Armageddon*, it’s a big-ass sky.

In: 14

Answer 1

Well space junk does end up falling back into the lower atmosphere. Its called orbital decay. Basically there is still enough atmosphere a few hundred kilometres up that is slows down spacecraft slowly. So space junk does erode. But the rate of humans putting junk into orbit is greater than its natural erosion.