When PopSci published Will Snyder's article on terraforming Mars, we opined that the Mars Society's colonial flag could use some sprucing up, so we asked readers to submit their own designs. The week the article appeared, 42 Martian-flag mockups turned up in our inbox. Some featured elaborate designs and detailed explanations (which we've printed in their entirety in the slideshow), while others simply included a name. A couple flags were even sent anonymously.