I never understood how the U FOs could never avoid (or shoot down those HUGE slow moving 'Interceptor; missile or why they just couldn't send more than 3 at a time; or how they couldn't just laser the $%$##@! out of the Moonbase in the first place...You know, I never understood why the UFOs had to pass by the moon to reach the earth. Space is big. Just approach our planet from the other side.
(And this was me as a 9 year old watching the show also wondering what happened to all the Marionettes too 
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