Across the Sea of Suns
Gregory Benford
 Radio astronomy on the Moon in 2021 reveals the presence of life by a nearby red dwarf, on a tide-locked planet. To investigate them and the message they are transmitting, Earth's governments repurpose a space colony that was to be stationed at one of Earth's Lagrangian points and convert it into Lancer, a Bussard ramjet powered interstellar ship based on a crashed alien ship discovered in the Mare Marginis on the Moon, and send it to investigate. In 2061, it arrives and discovers a primitive biological race of nomads broadcasting en-masse with organs adapted to emit and receive electromagnetic radiation; their transmissions were blurred by various nomads falling out of synch with the rest. Close up, the transmission is discovered to be an old radio show from the 1950s - the signal the EMs (as they are called) consider best to reply to Earth with. A curious satellite is discovered in orbit, from at least as far back as a million years — roughly when an anomalous meteor shower destroyed the EMs' civilization. On Earth, international commerce is brought to a standstill when mysterious spaceships drop sea creatures dubbed "Swarmers" and "Skimmers" (for their behaviour; Swarmers swarm ships and head-butt them until they sink, and Skimmers simply jump and skim around like dolphins). They begin multiplying and the Swarmers begin attacking humans and all their works on the seas, high or otherwise. The Ra expedition's first contacts go poorly. The attempt to examine and enter the more interesting of the total of two satellites prompts a massive retaliation by the satellite with plasma weapons that kills most of the crew involved in the attempt. The attempt to contact the EMs on Isis does not go well either; the EMs are confused by the presence of a human on the surface. They had been expecting a reply from Earth itself. In the confusion and surprise, they attempted to simultaneously broadcast their lengthy and elaborate summary of their history and culture, and also to see in more detail the messenger. Unfortunately, in order to see in radar, radar must be broadcast, and the narrowing gaze of the EMs and all the other transmissions literally cook the communications specialist alive. The standby team misinterprets this tragic incident as a deliberate attack and massacres the lot of EMs. Nigel works with the mathematicians and other experts to interpret the original transmission and later ones. His analysis reveals that their technologically advanced Space-age civilization had attracted the attention of machines, and perished in a massive and prolonged deliberate orbital bombardment that levelled their cities, infrastructure, and civilization. The bombardment of asteroids was severe enough to crack open the crust of the planet and permanently alter for the worse the EMs' ecosphere. The EMs drew to the utmost on what was left of their genetic engineering and biology, and radically altered their bodies to use silicon and transistors for a nervous system and so broadcast; the watching satellite is programmed to react to high technology, not inbuilt features of organisms, so this way the EMs will be able to broadcast their message and possibly help out other biological races. No sooner has some genuine two-way communication been established than new orders come from Earth, to move on to a new system where they think the Skimmers and Swarmers may've come from originally. En route, they preoccupy themselves analysing reports from the far-flung space probes: everywhere except Earth that traces could be found, anomalies like other Watchers abound. Walmsley theorizes that a machine-based race that was systematically destroying or guarding planets supporting organic life was responsible for these anomalies; the Swarmers represent a first strike at Earth, which had thus far eluded the machines' attempts to kill it, since the assigned Watcher (as Nigel calls the satellites) was destroyed by the Mare Marginis wreck. His theories are generally disregarded as being too speculative; the sober consensus agrees that Watchers are simply a common form of weaponry left over from the suicide of biological races, and the Swarmer invasion simply a grab for a fresh and relatively unspoiled world. At the next system, Ross 128, a moon like Ganymede is found with a Watcher around it. Initially it is taken as a disproof of Walmsley's Rule that Watchers will appear around any depopulated world that had once harboured technologically advanced biological life, but the de facto leader (Ted), who has always disliked Walmsley, attempts to covertly force Walmsley into hibernation until the long-planned-for return to Earth. Walmsley breaks out part-way through the necessary medical preparations and escapes to the moon in a submersible. Avoiding the people the Lancer sends out in pursuit, he discovers a much-reduced sapient civilization that had links to the EMs before the Watcher came. The Watcher prevents them from ever reaching the surface and thus from developing much technology, but it cannot complete its task and kill them—they are protected by ten kilometres of ice, which Walmsley remarks would insulate them from even the worst the Watcher could do: cause the sun of that system to go nova. The two are in a stalemate. During the standoff, news comes in from Earth (delayed nine years by the speed of light) that the Swarmers have begun land invasions; the tense superpowers each suspect each other, and escalate the conflict into a full-scale multi-party nuclear war. The machines, who had attempted to engineer just such an internecine conflict (more efficient than attacking a unified humanity), send their flotilla against Earth, when the defences are denuded, destroyed, or depleted. This grim news galvanizes the crew to do something. They agree to reactivate the fusion drive and turn the plume on the Watcher. This tactic cripples the Watcher, but its retaliation does even more damage to Lancer; worst of all, the drive system is destroyed. At some point after the publication of one or more sequels (beginning with Great Sky River, for the American paperback edition), Benford appended a new ending onto the original just-described ending of the novel. The following section is from the Second Edition of the book to bridge over to the continuance of the Galactic Core Saga: The Watcher is eventually blinded by being coated with a life-form native to the moon, which eats metals and other such materials, thus enabling a boarding action. The boarding parties discover that in exchange for their horrific casualties, they have obtained a map of the galaxy marked with places significant to the machines, and a sleek fast vessel to take them to those places. Now the leader, Nigel vetoes suggestions that they return to Earth and quoting Adventures of Huckleberry Finn ("Le's all slide out of here one of these nights and go for howling adventures amongst the Injuns over in the territory and I says all right, that suits me.") energizes everyone for a voyage to the Galactic Center, the most important place of all for the machines. Earth's ocean-borne myriads, now partnered with the Skimmers against the Swarmers, will just have to fend for themselves.