As you level up does difficulty for previous missions scale up? I'm level 17 and want to go back and explore the moon and earth but not if it's gonna be insanely easy now. I replayed a moon mission and got some level 17 gear from it but couldn't really tell if it was easier or not. I want to help a friend with the Earth strike but we don't want it to just be me steamrolling through everything. Also, is there locations on each planet that the missions don't take you to and that you have to just find in explore mode?