界海
No sooner has two-way communication been established than new orders come from Earth to move on to Ross 128, where they think the Skimmers and Swarmers may have originated. En route, the crew analyze reports from space probes. Walmsley hypothesizes that a machine-based race is systematically destroying or guarding planets supporting organic life, and is responsible for the anomalies; the Swarmers represent a first strike at Earth, which had eluded the machines' attempts to kill it, since the assigned Watcher (as Nigel calls the satellites) was destroyed by the Mare Marginis wreck. His ideas are regarded as being too speculative; the consensus is that Watchers are simply a form of weaponry left over from the suicide of biological races, and the Swarmer invasion is a grab for a new world.