He comes out of the flashback just in time to sound the alert for a lunar tremor that, thanks to his prompt action, kills only two of his fellow crew members. He remembers his dead dog, realizing that Laika could not actually have saved him, for she was separated by 5 years time and a barrier that no man or dog could ever bridge (her death). It was his never sleeping subconscious mind, sensing the tremors, that knew how to wake him, by making him dream of Laika's barking as she did in the earlier earthquake.