 Later , Lovell used some otherwise idle time to do some navigational sightings , maneuvering the module to view various stars by using the computer keyboard . However , he accidentally erased some of the computer 's memory , which caused the Inertial Measurement Unit ( IMU ) to think the module was in the same relative position it had been in before lift @-@ off and fire the thrusters to " correct " the module 's attitude . 
