Qualifying and quantifying impactors (was Shooting down meteoroids)

--- In spacesettlers, sraj wrote:
> Looks like habs on the Moon or in space will have to be
> equipped with systems to actively engage and shoot down
> meteoroids

How did you draw that conclusion?
http://writings.mike-combs.com/case_spc.htm#Meteor_Storm

===========================
Warning! Warning! Meteor Storm!

One widely perceived advantage of Martian settlements
over orbital ones is that they'll have the atmosphere
of Mars to protect them from meteors. But it turns out
the danger of meteor strikes in space is much more
modest than "Lost In Space" has led us to believe.
O'Neill estimated his Island Three model (biggest
cross-sectional area means greatest risk) might expect
to get hit by a one ton meteor once every million
years. One should expect a meteor the weight of a
tennis ball to come along about every three years.
Even if it did penetrate the hull, such a puncture
would mean a routine, minor repair, not an emergency.
===========================