But that was far off, in a remote and unimaginable future. Today a gummy slick of microphages covered the land from equator to poles, waiting for anything with a GACT sequence that invited disassembly.

Night fell, for the seven hundred and fiftieth time since the end of the Great War. The stars came out, bright and steady in the black sky. Phobos raced across the heavens, west to east. The purblind phages were unaware of its presence, or of the rising of Jupiter and Saturn.

But others on Mars knew. Three hundred kilometers from the barren equator, in the dead center of a low, flat valley, a ten-meter circle of surface released into the thin air a mist of chemicals. Any GACT or GACU form would have died within milliseconds. The disassemblers were made of sterner stuff, but they knew enough to recognize danger. A wave of microphages surged backward, clearing an annulus of bare gray scree around the misted ring. Those disassembler phages unlucky enough to be caught within the ring writhed, retreated toward the middle, and withered to a small heap of desiccated powder.

A puff of warmer air from below dispersed their dust. In the center of the ring a black dot had appeared. The dot widened into a dark open disk, through which a fiat circular platform slowly rose. The microphages retreated farther, recoiling from the blown spray at the platform’s perimeter.

Two suited figures stood at the center of the platform. The woman was holding the hand of the little boy, and pointing upward. He was about four years old, and showed far more interest in the writhing circle of microphages and the bleak landscape beyond than in the starry sky.

“Do you see it?” The woman’s voice was wheezing and husky, and her back was oddly twisted. She shook the child’s hand impatiently. “You’re looking the wrong way. Over there. The brightest one.”

The boy was tall for his age, and sturdily built. He followed her pointing arm to the place where rising Jupiter hung above the eastern horizon. Dark eyes gleamed behind the suit’s visor, but his scowl was invisible in the dim light. “It’s not big. You said it would be big.”