The Advanced Camera for Surveys (ACS) is a third-generation Hubble Space Telescope (HST) instrument. ACS was installed during HST servicing mission 3B. During servicing mission 4, the ACS WFC was repaired after an electronics malfunctions in 2006 and 2007. For more information on the malfunctions and repair, please see the ACS-R website at Goddard Space Flight Center.