I'm very sorry, I don't quite get it...
In the other post, I also used 2mc^2 as the intrinsic energy to do a similar calculation.
If I let "m" be the mass of ONLY the matter and let "m" be the mass of ONLY the antimatter, shouldn't the total intrinsic energy be mc^2+mc^2=2mc^2?
Say for example, if I get the answer for "m" to be m=12g, then I can say 12g of matter AND 12g of antimatter is needed for the spaceship to achieve escape velocity, right? (An EQUAL amount of matter and antimatter annilhilate, yes?)