Contagious by Scott Sigler

it.

It did that by tracking broadcast signals.

Broadcast signals meant several things. First, they meant a planet that could support advanced biological life—predictable ranges of gravity, density, temperature, gases and liquids. Second, broadcasts meant a predictable range of resources—odds were, a planet of nothing but silica and sulfur could not create technology capable of sending signals into space. Finally, and perhaps most important, broadcasts indicated a large population capable of performing technically advanced tasks.

And that was important when you wanted slave labor to build your colonies for you.

Colonies, like exploration, are prohibitively expensive operations. Enslaving a native population provides a low-cost solution. It also helps cut off a potential interstellar rival.

If all went well, if the planet had suitable gravity and atmosphere, the object could get cracking. It would seed the planet with machines that could build a portal, a portal that connected two places so far apart that no living thing, nor the children of that living thing, nor the great-greMargaret, Amos and Clarence sat in the MargoMobile’s at-great-grandchildren of that living thing, could survive the trip by any other means. With the portal, however, such a trip took place instantly. Hundreds of light-years traversed in the blink of an eye.

This object, this Orbital, had arrived in Earth’s solar system some twenty years ago after detecting multiple signals: radio, television, microwaves. It approached slowly, cautiously, because there was always the possibility sentient life was too advanced and would see it coming. So the Orbital watched for a few years. It analyzed, eventually reaching the conclusion it could move into a low, stationary orbit without being detected.

Once the Orbital drew to the operating range, it spent more years watching. While there were multiple shapes and forms in the signals, the dominant species was almost always present. Suffice it to say that thanks to repeated image analysis, the Orbital knew a human when it saw one.

After seven years the Orbital knew humanity’s technological capabilities. It could identify major population centers and, more significantly, areas of little or no population. It could not understand any languages, but it didn’t need to—it would accumulate language once the probes were successfully deployed.

The Orbital carried eighteen of the small, soda-can-size probes, each of which could cast over a billion tiny seeds adrift on the winds. Each seed contained two main elements. The first was the microscopic machinery needed to analyze potential hosts and hijack their biological processes. The second was a tiny, submicroscopic chunk of crystal. This chunk matched exactly with one in the center of every other seed and, more important, inside the Orbital. This irreplaceable, unreproducible chunk was the template, the device that reshaped the molecular structure of biomass so that it became the material needed to build a gate.

The first probe had been a total failure. Bad luck with the weather. The second probe actually produced several connections, but, unfortunately, they were all with nonsentient animals. When that happened, the seeds simply shut off—a half-formed triangle on a caged or penned domesticated animal could potentially alert humanity to the hovering threat. The seeds also needed sentient hosts to develop workers that could communicate and work together, could use tools and vehicles, could learn about the area and potential dangers.

It wasn’t until the sixth probe that seeds latched onto a sentient being. Although those seeds died early, the Orbital was able to gather some biofeedback. It analyzed the data, identified key problems, then modified the next batch accordingly.

The seventh probe proved closer still. More development, including successful creation of the biological material needed for worker construction. These were the strange red, blue and black