In the last year 156 objects floating through space came within 5ld of Earth. So if we look at this in a simplified 2 dimensional sense if we have a dart board 5ld in radius with the Earth at the center, that dart board got hit 156 times.
The total area of the dart board is:
5ld squared pi, converted to square miles….
1.25 million squared pi
~5 e12 square miles.
the area of the earth disk in the center would be
4,000 miles squared pi
or 5 e7 square miles
By these calculations we know of an object that should hit us about 1 in 100000 years. Since we know that the Earth gits hit by shit more often than that we have a lot of work to do on our space program.