See you again after a major objective has been achieved.
This phrase may originate with
the Apollo 8 mission, the first time in history humans had passed behind
the other side of the moon from earth.
CapCom Gerry
Carr spoke to the three astronauts more than 200,000 miles away, "Ten seconds to go. You are GO all the way." Command
Module Pilot James
Lovell replied, "We'll see you on the other side", and Apollo 8 disappeared behind the Moon, the first time in history men had been occulted. For 34 minutes there would be no way of knowing what happened.
Source: history.nasa.gov