How to increase your Cryo Archive Security Clearance Level in Marathon

Marathon's Cryo Archive is a maze, made only more complicated to navigate by the fact that you need Security Clearance to access most areas. It's a system unique to this endgame map, and it's not immediately obvious what it is and how to increase it.

But if you want to extract from the ship in one piece, let alone with any high-end loot from the elusive vaults, then you need to understand how Security Clearance works. And preferably, you'll find out before you queue into a match with your loot on the line.