The year was 2191. The two most massive ships ever assembled in Earth orbit, called Hope and Grace, departed with fanfare to Sata. Each ship was fourteen kilometers from bow to stern and carried 1,500 passengers. It was an extraordinary venture, the likes of which had never been attempted.
Hope and Grace had the most sophisticated debris avoidance systems ever produced to date. The engineers had learned the typical density and mass of debris occupying the twenty light years between Earth and Sata from the journeys of numerous probes. Much of their knowledge had been gained the hard way; many probes were annihilated on their way by collisions with interstellar particles. The models estimated that the two colony ships each had a better than 90% chance of reaching Sata intact.
In 2270, Hope reached Sata alone. Grace and its passengers were converted to dust by a collision with interstellar debris. The ship was destroyed utterly by a body smaller than a thumbtack.
The first woman set foot on Sata. Her name was Io. She was born on Hope. Like most of the ship's living passengers, she had never before stood on a planetary surface. Io had no word for sky. Her only analog was atmosphere. The sight of a horizon confused and delighted her. She removed her helmet and breathed the world's strange air.
Human investigation revealed of Sata what probes had not. It was not only habitable but inhabited by complex animal life. Insectile creatures claimed its alien forests. Its waters were filled with things resembling Earth's primitive ocean life. A plethora of burrowing creatures lived and thrived under Sata's verdant surface. The astonishing news put a hold on colonization. Some people lived nomadically on the surface for short periods of time. They interacted with and studied the indigenous life. The aquatic life was all inedible; too much of it metabolized ammonia. But some of the insects were rich in protein, even delicious when cooked the right way. It reminded the oldest of Hope's passengers of home.
One curious person stunned and roasted a digging creature. While they sat enjoying the cooked flesh, the dirt opened up underneath them. They were swallowed. They were never found again.
Later, another person reproduced the experiment. She captured one of the burrowing creatures. It was one of the larger specimens she'd seen. Sata's explorers had come to call the species Dugs. She was ravenous and curious, so she killed the Dug and ate it.
Nature never invented predators on Sata. The Dugs were scavengers. Scavenging was the closest thing they knew to what the humans were doing. It tried their comprehension that the humans inflicted unnatural deaths on their prey in order to scavenge it.
A signal completed its twenty-year journey to Sata. An anomalous solar flare sterilized Earth and Luna. The Venusian colony was destroyed utterly. There were a few on Mars who survived to send the message. The colony had never been self-sustaining. Twenty years ago, they had no more than two years before they starved. No other colony ships were ever sent after Hope and Grace. Sata would be the last self-sufficient human world in existence.
Hope's passengers decided that none of the indigenous life was dangerous enough to them to justify waiting for colonization any longer. They founded a colony. In addition to cannibalizing Hope, they excavated the ground to find metals and stone useful for construction. Their digging machinery interfered with the local ecology, but that wasn't a concern to the colonists.
The Dugs observed and listened to the colonists. They weren't able to get very close. The terrible vibrations the humans sent into the ground were unbearable to a Dug. It was to them like flashing lights and deafening music would be to a human. Some inventive individuals used padding to reduce the intensity of vibration reaching their hands, but doing so made them almost blind. The Dugs guessed that the digging might stop once the colonists had finished constructing their dwellings, and perhaps then they could coexist in that area, but the humans kept on building more and digging in more places.
The digging went on for years. There was no sign of it ever ending. The colonists mated and reproduced and thus required more and more resources for every infant they conceived. Sometimes Dugs went missing. The consensus was that they were typically being killed and eaten by the humans. This alien behavior, the murder of their kind, disgusted the Dugs like nothing ever had before.
A thousand Dugs gathered near the human colony. They waited for a human holiday. The Dugs had learned to identify holidays by how the humans all stopped work for the day. On holidays, their deafening, blinding digging finally stopped.
The Dugs emerged from the ground everywhere, in groups, wielding the best and sharpest scavenging knives they could create. They learned that the most effective way to kill a human was to climb onto their backs and slice their throat. Dozens of colonists fell to their knives.
Then the humans revealed strange weapons that spat light so hot it melted the ground. No Dug had ever known anything like it. It was a slaughter. It paralyzed and baffled them. More than four hundred Dugs died that day. Nowhere in the Dugs' recorded history had so many of their kind died in such a short time.
A young biologist suffered grievous knife wounds to his legs. His name was Ruby. He was in the infirmary for several days while he recovered. The doctor explained that his muscles were so damaged, he might never walk without a limp again. Ruby fashioned a walking stick from one of Sata's plants.
He could not sleep without dreaming of laying injured and helpless on the ground. Every night he saw the eyeless Dug mount his chest and prepare to slit his throat. Every night he saw it dissolved by laser fire at the last possible moment.
In response to the attack, many of the colonists proposed eradicating the Dugs. The more level-headed colonists observed that the Dugs constituted a vital part of the local ecology. They scavenged decaying creatures and they helped the plant life to exchange spores. If they killed the Dugs, it would cause too much damage to the rest of the environment.
Ruby sat in quietly on meetings where the fate of the Dugs was discussed. Nobody ever suggested that the Dugs shouldn't be killed on the simple basis that they had a right to their own lives. That they were sufficiently intelligent to mount an organized attack on their colony, and that meant their eradication would be equivalent to genocide.
Ruby knew of no one before him who could be said to have betrayed their own species. There were uncountable traitors of nations and governments, but none known for murdering humans to spare nonhumans. Maybe they did exist. Maybe history erased them. Maybe they were too incomprehensible and too shameful to remember. Ruby wondered how people would judge him. He gave up the line of thought when he realized that, besides the two thousand on Sata, there were no other humans to remember or forget his actions anyway.
He toyed with the idea. He imagined how he might accomplish the eradication of his species. He wondered if he should do it. He wondered if he was crazy.
Ruby's mind was made when the colony voted to exterminate the Dugs, and to hell with the ecological consequences. The colonists had their own Earth specimens to introduce into the environment, anyway, that would not be dependent on the Dugs' existence. Ruby was among those tasked with discovering an effective way to kill the Dugs.
With the pretext that the information was needed for his assignment, Ruby learned from Hope's information archives how to assemble a bomb. He made two. He disguised one and gave it as a gift to his friend before she left Sata for a temporary work assignment on Hope. He hid the other in the center of the colony.
Ruby took his walking stick and went for a long walk into the wilderness. When he could walk no further, he found a rock and sat on it. He wept and said a prayer.
Some colonists noticed a flash of light in the sky above them. A second later, the Dugs experienced the most violent shockwave in living memory.