Micrometeorites are basically micrometeoroids that have survived entry through Earths atmosphere.
Most micrometeorites come from comets but a very small percentage come from asteroids. This distinguishes micrometeorites from the meteorites you are used to seeing because most meteorites do indeed come from asteroids.
We are consistently bombarded by these little specks of cosmic dust at a rate of about 30,000 tons/year and we can find them on the ground and on roofs at about 1 micrometeorite per square meter per year. So they are all around us and we only need to find the best methods to search for them.
At the South Pole from a water well where scientists get their drinking water, and recently 30,000-50,000 have been found along mountain ridges in the Antarctic as well.
In 1872 scientists aboard the Challenger discovered little metal spheres and concluded that they were not likely man made.
It is only very recently that we have been able to find micrometeorites in urban areas, this was once thought impossible.
Oddly enough micrometeorites can tell us a lot about the early formations of the solar system and even perhaps about the conditions of when the Earth was forming.
I study micrometeorites because they fascinate me. Every one I find is different from the other yet they all have similar characteristics as well.
One of my favorite quotes is by Donald Rumsfeld, ‘There are known knowns. There are things we know that we know. There are known unknowns. That is to say, there are things that we now know we don't know. But there are also unknown unknowns. There are things we do not know we don't know.’ Now political views aside, I think this can apply to micrometeorites as well, and I'm excited to see what we can find that we did not know.