The invention relates to a separator device for separating the on-board and ground portions of a launcher fueling module, the device comprising: a locking system having a locking finger (50) mounted on the ground portion (22) and having a blocking portion (523), and a locking pin (42) on the on-board portion (21) co-operating by engaging with the blocking portion (523) in order to hold the on-board portion (21) and the ground portion (22) in a locking position. The separator system further comprises an actuation system that, under vertical movement of the launcher (10), enables the blocking portion (523) to be disengaged from the locking pin (42), whereby the on-board portion (21) is suitable for being separated from the ground portion (22). The invention also provides a method of separating the on-board and ground portions of a launcher fueling module, which method is implemented by means of such a separator device.