Mars is the fourth planet in our solar system. Due to many science fiction films and television series of the 1950's and 60's, some people believed that aliens living on Mars (aka Martians) would invade the planet Earth.
While searching for the bio weapon antidote developed on the secret H.A.R.M. Space Station, Cate Archer found a series of photographs of multiple meteor showers passing the Mars perimeter and heading inwards.
Mars on Wikipedia