You can either use a copy of your backup image and roll it forward to the time right before the table was dropped (point-in-time recovery), or you can restore a logical backup through the exp utility.

External recovery refers to actions that take place outside of work—e.g. in the free time between the workdays, and during weekends, holidays or vacations.

As for us, we've started using our plane time as a work-free zone, and thus time to dip into the recovery phase.