How about: radiation hits water, hydrogen outgasses, oxygen oxidizes
Sagan thought that Mars held sterlizing amounts of hydrogen peroxide.
By the way, the Earth will be in the midst of the frament stream of Comet Shwassmann-Wachmann 3 in 2022,
and Apophis will pass under the com sats in 2029.
Mars sure is fascinating, as are mankind's fantasies about it.
Second by the way, someday you'll all figure out who actually came up with the Direct architecture.
have a good day,
E.P.