Dr. Andrada flinched at the frigid air that washed into the space in its wake. They were looking down a straight tube about ten meters long, large enough for one person to work comfortably, or for two to pass each other if they didn’t mind bumping bodies. Its walls were studded with long neat rows of smaller hatches about as wide as a splayed human hand, each with its own little handle. Hundreds of them. Closer to the entrance these bore neat machine-printed labels and bar codes; farther away they were blank. Next to each one of them was a blue LED; these provided the space’s only illumination.