On July 14, 2012, the Kepler spacecraft experienced a disruption in science data collection due to a pointing error. The anomaly was detected during a routine semi-weekly contact with the spacecraft on July 16, 2012.
The spacecraft remained at science attitude when the anomaly occurred, but transitioned from fine-point to coarse-point mode. In this mode, the telescope continued to monitor the target stars, but the larger pointing jitter negates the scientific use of the data.
Preliminary analysis indicates one of the spacecraft's four reaction control wheels has ceased responding to flight software commands. The spacecraft design is tolerant to the failure of a reaction wheel and can meet all mission objectives operating with three wheels.
The mission operations team has downlinked engineering data from the spacecraft that will assist in anomaly analysis. Engineers are evaluating the data to determine root cause of the incident.
Contingency plans are being readied to return the spacecraft to science operations. Moreover, long-term plans will consider further anomaly analysis and fault determination, and potential mitigation measures.
Updates will be provided as additional information is available.