A Russian government commission says upside-down angular rate sensors installed on the first stage of a Russian Proton M/Block DM-03 rocket most likely caused the vehicle to crash seconds after its July 2 launch.
The launch vehicle, carrying three Glonass-M navigation satellites, crashed 32 sec. after liftoff from Baikonur Cosmodrome in Kazakhstan due to loss of stability in its yaw axis.
The investigation revealed that at least “three of six angular rate sensors were installed incorrectly,” Roscosmos spokeswoman Anna Vedishcheva said July 19, though electrical connectors between the sensors and the first stage were installed correctly and were properly aligned.
Electrical tests were then performed, but because the sensor connectors were correctly aligned, they passed the tests. The error went unnoticed, and the launch proceeded with the misplaced sensors.