Since October 2012, U.S. Air Force Space Command’s Space and Missile Systems Center (SMC) has been analyzing, characterizing, testing and implementing modified battery charge control rates across the GPS IIR/IIR-M fleet. This fleet of 19 satellites comprises more than half of the Global Positioning System (GPS) constellation. As of Nov. 15, 2013, the USAF’s 2nd Space Operations Squadron (2SOPS) completed the modification, which will extend the life of these satellites’ operational capability.