It is integrated into the Mineral Storage. It creates a vacuum environment for minerals, preventing them from oxidising and reducing the likelihood of weathering when the vault overflows.
It can be found in any expedition that includes Science Vessel (for humans), Queen (for xerjs), and Investigator (for tosses), with a probability proportional to the expedition's time in days.
Once per hour, the active Vacuum chamber has a 0.125% chance of breaking down.