everyone must surely know ..
Obviously, we are looking at remnants (eg. spent shells) of a major war between the Face on Mars and some Hale-Bopp sectarians (who opted for a planet instead of a comet, which is too hot and gassy for comfort). That also of course explains all those craters all over the place. Apparently Marvin the Martian acted as the local UN-type arbiter in the war, but lost his temper and walked out of the peace conference.
Doesn't everyone KNOW this by now? .. or are you perhaps all part of the cover-up too?