This is the best design I can do right now taken the tools I have (Kindle crappy Picasso app). Underneath it can say: Our mission: To make the Universe a better place one planet at a time. For a motto I suggest... "In this galaxy there's a mathematical probability of three million Earth-like planets. And in the Universe three million million galaxies like this. And in all that, perhaps more-- there is only one of each of us." -Dr. Leonard McCoy
Of course, this would be simply a banner or something of the sort. Then again, for the uniform (Rank/Division), we could have something like this. The E, M, and C would be in a nice, professional font, E standing for Engineering, M is Medical, and C is Command. Earth would be colored in fully on every outfit. However, say you were in Command. E and M bubbles would be duller versions of the original color, while the C bubble would be bold and bright, identifying you as a Commanding Officer.