McArthur works at the back panel of the AR rack in preparation for IFM during Expedition 12

ISS012-E-13047 (20 Dec. 2005) --- Astronaut William S. (Bill) McArthur Jr., Expedition 12 commander and NASA space station science officer, works at the back panel of the Atmosphere Revitalization (AR) rack in the Destiny laboratory of the International Space Station as he prepares to perform in-flight maintenance (IFM) on the Major Constituent Analyzer (MCA).