Each day are on the multiplayer server randomly spawned (hint: only in given locations) three Nomad Depots. This will happen only in the Inner Core Sector and/or Canis Sector. Each this Depot have different colour (green, blue and red) and contains an upgrade token with the same colour, which are usable for upgrading players battleships and dreadnoughts. Green is for shields, Blue for engines and Red for weapons. More details about this multiplayer feature can be read in the CF Wiki here.