As a purely emergency procedure, all Galaxy-class star ships can separate the saucer section from the stardrive section. The purpose of this separation is to send many of the families and non essential personnel in the saucer section while the stardrive section with the warp drive says behind to defend against enemies, as seen in Encounter at Far Point, Part I. In cases of extreme emergency the saucer section is also able to land on a planet although is not able to enter orbit again, as seen in Star Trek Generations. Previous versions of the Enterprise could also separate, however they could not be joined again in space as the Galaxy-class star ships are able to.
To download a video example of this separation procedure click here (3020K)
Commanding the Enterprise-D is Capt. Jean Luc Picard played by Patrick Stewart . Other senior officers include: Cmdr. William T. Riker played by Jonathan Frakes, Lt. Cmdr. Data played by Brent Spiner, Lt. Geordi LaForge played by LeVar Burton, Lt. Worf played by Michael Dorn, Chief Medical Officer Beverly Crusher played by Gates McFadden and Counselor Deanna Troy played by Marina Sirtis.