I've always assumed it's just art, or maybe an altered font. I do have a nice Illustrator trace of it, but can't imagine what font it may be derived from. I will check back here just in case someone else might know. I'd sure love to have that font!
I'd love to get the Barsoom font, actually.
Here's an example of A-Z in Martian (Barsoomian) text.
http://disney.go.com/johncarter/translator-share/#/translator-share/QSBCIEMgRCBFIEYgRyBIIEkgSiBLIEwgTSBOIE8gUCBRIFIgUyBUIFUgViBXIFggWSBa
Or a readable font that has the look of the Barsoomian letters.
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