What is the quantity of mass received on Earth From Galactic radiation?

Answer 1

The only galactic or extragalactic source of mass for the Earth would be cosmic rays (which are really mostly high energy protons).

I don't know exactly what the rate of cosmic ray hits are, but from my experience with bubble chanbers, it seems like it's of the order of about one per square meter per second.

So it's insiginificantly, breathtakingly small compared with the mass of the Earth.