**5.2 Extended mission experience (equinox mission)**

*RCS thrust branch swap:* In March 2009, Cassini swapped over to the backup branch of RCS thrusters to replace those that had been in use since launch, since the prime thrusters were exhibiting increased chamber pressure roughness and decreased thrust (e.g., these thrusters were displaying end-of-life characteristics).

*Loss of an ATC temperature sensor:* Temperature readings are reported to each ATC from two sensors. For ATC #7, these sensors are mounted on opposite sides of the ME, and are used to monitor chamber temperatures. In 2009, during a maneuver, one of these sensors began to report erroneous data. It was speculated that the failure was most likely caused by a soft short.

*Fix:* The SOFS team uplinked a command to declare the sensor "dead" (not usable), since the ATC was able to function with only the single remaining sensor. Also, a new operations strategy was developed to eliminate the use of ATC #7 (implemented in S56).
