This is one of the three easiest achievements to get in this game. When you start the first campaign, there will be a point where you eventually land on the moon. There will be some orientation pointers to go through but, once this is done, it will set a waypoint for you to follow. The temptation will be to use the jetpack to reach your destination. To get this achievement, just forgo the jetpack, walk there instead and it should unlock along the way. If it doesn't, just explore around the location for a bit and it will unlock.