Seek ye not consistency in the rules of the English language; that way lies madness.
Whereas in the speculative future, people are unlikely to say they live on the Mars (etc).
Ming the Merciless sidestepped the issue by labeling his buttons in capital letters. [1]
[1] http://3.bp.blogspot.com/-Z9E0myUALKw/UIRPUfNFiBI/AAAAAAAABE...
Seek ye not consistency in the rules of the English language; that way lies madness.