[blue1]

Flags are generally designed to stand out against the background, so I am not convinced that using red on the martian flag is such a good idea. Which is also why there are few green flags in Europe, and also why the white flag of House Stark does not make any sense :-)

[otp124]

The majority of the flag is white though, and only a small portion is red. So I wouldn't consider this much of an issue. My understanding is that sandstorms are likely to reduce visibility at great distances anyways.

[falsedan]

The field is white, so the red will stand out just fine. More pressing though is: what happens when the flag is soiled by a duststorm ?