The target planet glowed blue and white on the display, just like their home world once had. But Mirda now was swathed in the ashes of too much industrial development, for too many years, and crowded with too many people. Talik remembered that dull grey pearl, and promised himself once more that this time they would not make the same mistakes. This world, Regon III in the catalogue, would provide a beautiful new home for the millions of hopeful colonists they carried in their gene banks.
The ship had been following the plotted orbital insertion track under autopilot, but now a computer squawked for attention and another display shifted: they were in orbit, and the targeting parameters were being calculated.
"Orbital insertion complete, Commander," Talik reported, "on track."
Commander Mondar emitted acknowledgement.
Talik noted that the indigenes were attempting communication through their primitive technology, but ignored it. There was no point in getting friendly with unevolved creatures when one was about to put them out of their misery.
Jake Ferrer looked up at the blue sky in bemusement. It was snowing. Or it seemed to be, if that wasn't impossible. He was an oilman working a project in Venezuela, it was right after lunch, and they were practically on the equator. Snow? Nevertheless, the sky was full of tiny white flakes drifting randomly down. He knew snow; he was from Montana, how not? He looked doubtfully at the humidity-beaded Millers he'd just taken from the cooler, shrugged and took a swallow as he looked up again. A flake landed on his sweaty forearm, and he shook his head. Volcanic ash, maybe? It wasn't snow, although in the sky it looked awfully like it. Even as he watched, the tiny bit of fluff seemed to melt into a silvery spot of moisture, and then it was gone. He blinked. He could have sworn that instead of evaporating in the heat, it had sunk into his skin. People in the street below his balcony were looking up and questioning one another in amazement.
Jake smiled his amusement at the general confusion. Another fluffy flake landed on his beer hand, and another on the back of his neck. His smile faded as he felt a tingling in his forearm just where the first flake had landed, a tingling which rapidly grew to pain. It felt like someone was cutting through his flesh with a serrated blade. He grimaced, and then groaned through his teeth as the agony spread rapidly through his whole arm, and itching began in his hand and neck. The beer dropped forgotten from his hand and his eyes bulged as he watched something mouse-sized crawl out of his arm. It looked angular, machine-like rather than organic, he thought frantically. Even as the thing fell to the balcony floor and scuttled into the motel room another emerged, and another. Screaming rose from the street below. Jake's final thought was the realization that he was being eaten alive.
In the hotel room the first machine had encountered a cockroach under the bed, and assimilated it. A gecko was the next victim, at which point the machine had enough resources, and information, to spawn the next generation of units. It spat out a succession of a dozen or so smaller versions of itself, these the size of a house fly, and then consumed its own substance to convert itself to several dozen more of the same.
All over the city, and in fact simultaneously over the whole surface of the planet, similar scenes were taking place.
The colony ship had seeded the entire atmosphere with nanobots, molecular-scale robots. These had used the elements in the atmosphere to build themselves into their programmed 'snowflake' form, and then to multiply their numbers so that by the time they fell to the biosphere their density was that of a blizzard. The programming allowed for the evolution of more than four dozen types of purification nanobots, including one which would have been as big as a bear, if it had been necessary. The nanobots transformed into whatever forms were best suited to the task at hand.