Destroyer of Worlds by Larry Niven

is
my
job. “We have time,” he prompted.
    â€œWe were testing the little guys,” Eric offered. “We fried one of their primitive comsats with a laser to see how they’d react. The Gw’oth launched a replacement very quickly. That got Nessus wondering about the extent of their sky watching. The Fleet would’ve been passing by in about seventy years, moving at three-tenths light speed by then. If there was any possibility the Gw’oth could lob something stealthy into the Fleet’s path. . .”
    Sigmund shuddered, even though the back story wasn’t new to him. You didn’t have to be a Puppeteer to find kinetic-kill weapons frightening. “Go on.”
    Eric stalled for a few seconds with a bulb of hot coffee. “Nessus ordered us to rig a cometary-belt object with a thruster. The idea was to temporarily modify the snowball’s orbit enough to seem a threat to the Gw’oth. He wanted to see if and how they reacted.”
    Baedeker’s forepaw scraped the deck. “And did they?”
    Kirsten shook her head. “We never did alter the snowball’s orbit.
Explorer
was recalled to the Fleet first. Nessus was needed on Hearth. He never explained. And of course the Fleet has altered course to avoid the Gw’oth.”
    Mention of
Explorer
brought sad reminiscence to Kirsten’s face and a flash of anger to Eric’s. Baedeker intoned something deep in both throats.
    There was a lot of shared history among these three, and Nessus, and the late ship
Explorer
. Sigmund tried, and failed, to interpret the Puppeteer’s reaction. Maybe it was emotional, not verbal.
    â€œWhy leave the comm buoy?” Sigmund prompted.
    Eric and Kirsten exchanged looks again. Kirsten said, “Soon after, Eric, Omar, and I went out again to scout ahead of the Fleet. Just we three. Either we had passed a test on the previous mission, or no one could be spared to chaperone us.”
    More soft, low-pitched chanting: jarring chords in some exotic key or scale that made Sigmund uneasy. Mournful? He guessed Baedeker had opposed the unsupervised mission.
    Kirsten shivered and kept going. “Instead, we went hunting for
Long Pass
. Given what its discovery revealed about our people’s own history, it was impossible to believe the Concordance”—Hearth’s government—“wouldn’t lob a comet at the Gw’oth.
    â€œAfter independence, Omar and I went back. Removing the thruster from the snowball prevented that particular remote-control attack. It didn’t guarantee the Gw’oth their safety. That’s why we left a hyperwave radio buoy in the cometary belt: to monitor Gw’oth radio chatter. I programmed the buoy to signal New Terra if it sensed any significant changes.”
    Baedeker squealed like an abused bagpipe, still pawing the floor. “In just a few years the Gw’oth went from simple comsats to visiting the cometary belt? And you gave them a hyperwave radio to reverse-engineer? They could have hyperdrive in a matter of—”
    â€œNot from us,” Kirsten said firmly. “They won’t find the buoy.”
    â€œAnd yet here they are using it,” Baedeker retorted.
    Kirsten shook her head. “We left behind a standard radio beacon, omnidirectional, on another moon near them, and directions for contacting us in major Gw’oth languages.
    â€œThe hyperwave buoy forwards to New Terra any radio signal from that beacon. The comm channel runs only one way—they can’t follow a reply to locate the hyperwave relay. It was all strictly for the Gw’oth to reach us if they needed help.”
    Sigmund restarted the holo. The signal had repeated for days, but the message was short.
    Amid fronds like drifting seaweed, a not-quite starfish—a Gw’o—undulated before them. Orifices puckered and relaxed rhythmically at the tips of its five tubular tentacles. Breathing? Speech? The