the thing that makes us lucky is that there is so much distance between stuff up there since the Earth is a gravitational trap for debris.
gravitational calculations are farily easy. given velocity, mass and all, you can calculate that stuff out for years. I wrong a program for my T81 that did it back in high school.
one shuttle had a BB sized fleck of paint hit it's wind-shield and left a D-battery sized crater... scary shit. Thing is, stuff up there is also travelling faster than a bullet.
go neo.