
UPDATE: Here's the official NASA page that explains the patch design: http://mplm.msfc.nasa.gov
The modules are named for significant engineers in Italian history, Rafaello, Leonardo and Donatello. This is the logo for the 3 Italian named modules developed by MPLM team members. The logo, copyrighted by Mirage Studios, depicts a ninja turtle in an astronaut flight suit.
A.C. Farley has also posted the artwork on his Facebook page, and had this to add:
They got in touch with Mirage and asked if we would do the patch. I got to do it because I am in love with the space program. They made enameled metal pins, embroidered patches and jackets and other stuff I never even seen.