The focal point of the Expedition XXIII emblem illustrates the beautiful planet Earth in the black expanse of space. The International Space Station (ISS) is shown traveling in its orbit around Earth. The ISS orbital path flies through the XXIII to show that this increment is building upon the missions that have gone on before and laying the groundwork for future missions. This illustrates the work being performed aboard the orbiting complex that will lead the way to eventual missions to the moon, Mars and beyond. The mission designation uses Roman numerals to illustrate the home nations of the crew, which are also represented by their national flags. The two stars represent the two teams that make up this expedition crew.
http://spaceflight.nasa.gov/gallery/images/station/crew-23/html/iss023-s-001a.html
http://commons.wikimedia.org/w/index.php?title=File:2010_ISS_Calendar.pdf&amp;page=13
NASA