“OS, are you there?” I call. No answer. Weapons outstretched, we creep into the hallway, lift ourselves up into zero g and back into the Endeavor. As we ease our way deeper into the ship, breathing heavily, we pause every few feet to listen. There’s the drip of urine processing, the dull roar of space, a thousand small clicks, a thousand small whirs. But no Rover sounds. I signal to Kodiak that we should continue.