You're right of course :).
More precisely: When the name pushed itself forward in my mind (something like 10 years ago when I came up with the background story for the game), I did do some online searching (I think I was interested in whether it had a meaning - but probably also checking where it might be used). And of course I got the same hit as you

.
Since I did play the Starcraft single player campaign (at least a bit), I'm pretty sure that that's where I "took" it from. But then, all great works are inspired by great works that preceded them, right

?!
Not sure whether I'd go for something like Mars-ara (though that doesn't gel with how I'd want to pronounce it), or a slightly different spelling (Marsahra ? Marsarra ? ) just to make sure I don't get Blizzard pissed :D.
P.S. I saw your reply a couple days ago, but was stumbling when it came to giving you a proper answer. Hope this is fairly decent :).