QUESTION:
Why would there be so many meteors on Mars?

ANSWER from Jeff Plescia on March 31, 1997:
The number of meteors hitting Mars is not that much different
from the number that hit the Earth or the Moon. There is a slight
difference in the number that make it to the martian surface
as compared to the Earth's surface; more hit the martian surface
because it has a much thinner atmosphere and so the smaller
ones do not burn up.

There are about a dozen meteorites that have been found on the
Earth which are believed to have come from Mars. These rocks
were thrown off Mars when a much larger meteor hit the martian
surface and threw a large amount of debris up into space. Some
of that debris escaped and eventually landed on Earth. There are
also meteorites that came from the Moon. Presumably there are
pieces of the earth that have been ejected from the earth and fallen
on the Moon, Mars, and Venus.