Talk:Mission/@comment-70.162.72.56-20130512212425/@comment-173.60.99.96-20130711003553

The levels correspond with your equipment's rank, not yours. So a Level 9–15 mission is recommended for weapons and Warframes between ranks 9–15.

Even missions on Mercury go up to Level 4, but it takes a looong time to get to Mastery Rank 4.