In Start Screen press and hold RB button on gamepad + (Y) button.
After a few seconds a map of all 81 bridge levels in Solar campaign are displayed on the screen.
This acts as a visual reminder of the disruption you need to bring to Aliens to reclaim the Solar System.
Reminder: the regular campaign map is accessed from Start Screen by holding the RB button alone. This summarizes all the districts that you own or that still belong to Aliens (blue versus yellow color).