The part I preferred is this one: > HAL has to be extremely careful before committing the first murder. It is possible that he wasn't entirely familiar with th

The part I preferred is this one: > HAL has to be extremely careful before committing the first murder. It is possible that he wasn't entirely familiar with the EVA procedure, it being one of the few tasks on board the Discovery that does not require his participation. Perhaps he needed to observe a dry run to study the astronaut's actions and calculate when he would be most vulnerable.