This one is in the southeast corner of the map, slightly southwest of where you begin the These Are the Bots optional mission. There’s a small building here and the symbol is on the eastern wall of it.
Go to the southwest corner of the map and look for the room you can drop down into that has oxygen. The symbol will be on the wall on the east side of this room.
Head into the compound in the southcentral part of the map, which is where you need to go to reach Tycho’s Ribs. From the entryway into the compound, head straight ahead and you’ll find the symbol on the back of the container that’s just east and connected to the small building with oxygen.