From NOAA:

*Details/Specifics of Change:* ESPC is currently not receiving GOES-15 West data due to a bad momentum unload. GOES-15 went into a sun acquisition mode and is unable to do any imaging. Operations personnel are trying to place GOES-13 into a full disk imaging mode.*

More here: http://www.ssd.noaa.gov/PS/SATS/MESS/MSG0821118.01.txt