Published in Visions of the Future (pub. Lifeboat Foundation)
There, ahead, lay the goal. A star, still so distant as to appear little different from the billions of others visible in all directions, although perhaps it was one of the brightest due to its proximity. Stars pixelated in all directions, as if pinpricks riddled a black shroud through which the brilliant exterior of the cosmos could be discerned. They lay ahead, behind, above, and yes, below. An interstellar probe (a ship of sorts, but an entity in a sense) floated freely in the cosmic void. Well, to say it was floating is putting it rather mildly. It was approaching the bright star ahead at a tenth the speed of light after all‐but there was little sensation to convey this astonishing speed, merely the steady impact of individual interstellar hydrogen atoms against the forward-facing surface. This wind was experienced consciously and vividly, just like a cool breeze‐but it was a rather repetitious experience after such a long voyage, many decades if one calls a 'year' the typical orbital period of a planet in the typical habitable zone of a typical star. We will need to agree on this sort of terminology, so we may as well get started now.
It was quiet, it was almost always quiet‐but there were exceptions.
COURSE VERIFICATION REQUIRED, blinked the periodic warning. This event was triggered every few years. Eyes (or cameras if you prefer) scanned the starscape in all directions, precisely locating specific stars, noting how their parallax against the background had shifted relative to the last time such a measurement was taken. Sure enough, an unforeseen variation in the gravity field through which the space-faring probe was traveling had effected a minute deviation in the intended course. Minimal though it was, this deviation would nevertheless compound to a substantial error over the interstellar distances between the current location and the target, the star ahead, still so remote. More measurements were taken, calculations were made, then verified. The measurements were made again and the calculations made again‐and verified again. No second chances out here, fuel is heavy and sparse. When the prescribed maneuver was established with satisfactory confidence it was set in motion. This consisted of no more than a few short bursts from specified lateral thrusters to give the probe a gentle nudge back on course.
It went back to sleep.
The next time it awoke, the star was considerably closer, now undeniably the brightest object in the sky, yet still no more than a spectacular point, not yet resolved as a disk at short focal lengths. Another minor course correction was effected. At this distance the probe was flying through a cloud of icy chunks that surrounded the star; most stars had such clouds. These bits of ice numbered in the trillions and some were large enough to coalesce into spheres, yet despite their vast numbers, they remained separated from one another by such unimaginable distances that the probe stood no reasonable chance of encountering one with even the most modest proximity.
It went back to sleep.
New message: SOLAR INTENSITY THRESHOLD ACHIEVED. The voyage was nearing completion. After decades of repetitive and uneventful travel, it was time to begin the multi-tiered process of entering the new solar system. The current solar radiation indicated entry into the system, but the star was quite distant, still a star, not a sun, not useful as a form of energy. At this distance other energy sources had to be used. The probe came prepared. Its forward-facing exterior consisted primarily of a single circular surface, curved slightly like a saucer, such that the outer edges protruded forward and the center recessed. In the center there was a hatch. It now opened. A pill, tiny relative to the probe, was projected out the hatch, ahead of the probe. It shot forward and then, at just the right moment, detonated a nuclear explosion. There was a blinding flash of light and the probe felt a hard jolt as the bomb pushed back against the ablation plate. What had previously been the soft wind of ultra-thin hydrogen gas was briefly interrupted by a sharp POP! as the ejecta slammed into the plate. The probe felt and heard this as a genuine tactile punch. It hurt (the probe had to perceive such impacts as harmful since, under any other circumstances, they could have indicated a serious problem) but the impact was extremely short in duration and the probe was well equipped to handle it‐but it wasn't over. Far from it. The probe proceeded to deliver a steady stream of nuclear bombs in this fashion, each one drifting ahead, exploding with a visceral pop that jolted the probe to its core with a sudden deceleration, then a moment to relax‐and then again, and again and again. Thousands of bombs were delivered in this fashion. Just when the probe thought it couldn't stand anymore of this abuse the process ended. The required deceleration had been achieved.
But the probe was still flying far too fast to stop in the solar system. It still stood the risk of flying right through, never to be seen again. Time for stage two. On the back side of the probe a cable began to unreel trailing further and further behind. When it finally stopped it had reached a distance thousands of times further than the probe's own length. At the end of the cable a small package began to change shape, a solid lump of homogenous matter. Operating at a molecular scale, this innocuous lump began to thin out. More and more of the lump's form spread to the periphery as a thin disk took shape. The disk grew in diameter while the central lump shrunk in thickness. Eventually an enormous diameter was achieved, thousands of times wider than the probe and only a few atoms thick. The inner surface was as perfectly reflective as mercury. Solar radiation from the target star steadily pushed back against the reflective sheet. Much time would pass in this stage.
The probe updated its survey during this time. The star was G-type and relatively stable. The system was host to three gas giants, all approximately equal in size, residing in the outer reaches of the system, and to two additional rocky worlds further in. The probe was giddy as it verified its earlier calculations and realized that both rocky worlds doubtlessly resided in the sun's habitable zone, one just inside the inner boundary and one just inside the outer boundary. Realize that the probe possessed‐no, was intentionally bestowed with‐a deep innate curiosity for all things living, whether biological or otherwise. At the core of its being it was driven by an insatiable thirst to discover other living things. This was, of course, crucial to its primary purpose for being. The verification that this system might host one, possibly even two, worlds with rich biology was too exciting to contain.
The probe soared into the system trailing the enormous solar brake for quite some time. If anyone had looked back toward the probe from the inner solar system, it would have been easily observed by the tremendous brilliant chute dragging behind it. Did anyone see it? thought the probe. It would be a while before such questions were answered.
The most dangerous maneuver remained. Yes, more dangerous than a thousand nuclear bombs. The chute slowly deconstructed in reverse, rebuilding the compact lump from which it has originated, the cable retracted, the precious matter, being so hard to come by in empty space, was stored away for future use. Using the lateral thrusters once again, the probe carefully steered almost directly toward the sun, now a blazing inferno. The probe was finally inside the orbit of the nearest planet. The sun was blinding and covered a large angular expanse of the surrounding cosmic sphere. It positively loomed ahead of the probe as if to refuse passage.
The probe shot in, still flying at a horrendous rate despite all its braking maneuvers so far. It aimed very carefully, and with a bit of luck grazed the atmosphere of the sun. The heat was unbearable, the noise a constant roar as the probe shot through the dense corona of the sun. Unlike the nuclear bombs which had been loud only as momentary pops, this was now a continuous and horrific assault of sound, so much so that it almost felt like it conveyed mass as it buried the probe in misery. The atmosphere was positively viscous compared to anything the probe had ever before experienced. The probe was not sure it could tolerate such abuse very long, but it was necessary. As the probe punched through the dense fog of solar matter it rapidly decelerated. This rendered the probe more susceptible to the sun's gravity such that the path of the probe's flight curved toward the sun as it skimmed tangentially past the solar sphere‐but it did not curve so much as to fall into the sun entirely.
Eventually, after a seeming eternity of terror, the momentum of the flight pulled the probe's path out of the solar atmosphere, away from the sun's gravity, and the probe shot away. Further and further it drifted now steadily decelerating the whole way since it was being pulled back by the sun's gravity. Would it ever slow down enough to stop, thought the probe, or had it miscalculated so that it would fly off into the galaxy to be lost forever? It slowly looped around and fell back into the star.
A second round of aerobraking commenced, just like the first, the probe crying for dear life as it skipped erratically across the surface of the sun, its outer surfaces glowing white hot with radiant and frictional heat. Again it shot off at an obtuse angle. A sigh of relief, a system check, all's well. This process repeated a few more times until the probe finally attained a safe spirograph orbit in which each pass would come in close (but no longer entering the corona) and then shoot off in a wild direction. All planetary and lunar body orbits are like this in fact but the spirograph effect is usually too small to notice. Over the course of many more orbits the probe steadily adjusted its path until eventually it completed its orbital insertion and achieved a solar orbit, nearly circular, just outside the habitable zone, beyond both rocky planets. In this way, it could fall in as needed at a later time.
From the moment the first alarm had fired and it had begun to deliver nuclear bombs to begin its descent into the solar system, decades (again, as indicated by a typical habitable zone) had now passed, almost as long as the probe had traveled through empty space to reach the solar system in the first place.
During this time the probe had begun its initial mission, that of surveying the solar system with particular attention paid to the two rocky planets. Both had liquid oceans, both had land. First things first though. The probe had a higher priority in the short term than investigating the solar system. It needed to find a planet, moon, or asteroid rich in material diversity. Heavy metals, carbon, silicon, many elements would be of use in fact. The second planet was home to two moons, barely large enough to form spheres. It was apparent at a distance that the inner moon was a chunk of amorphous rock and that the outer moon, slightly larger, was coated in a mixture of water and rock. Since the planet was in the habitable zone of the star, the water on the surface of the moon could conceivably melt at various times, but without an atmosphere, and therefore no pressure, it would doubtlessly transition back and forth between ice and vapor, never forming a liquid on the surface.
As to a more detailed analysis of the moon's composition, a closer investigation would be required. A small scouting probe was dispatched to explore the moons in the hopes of discovering the required resources. No doubt the planets themselves would be home to great diversity, but there were two problems posed by their exploitation. First, their gravity wells would be significantly difficult to escape from, and second, any action by the probe which might harm or redirect the destiny of evolution in the solar system was to be avoided with the greatest primacy.
Luck shown upon the probe's fate as the scout reported back that the outer moon offered most of the required materials in sufficient abundance. Those which were absent from the outer moon, were, with great fortune, to be found on the inner moon. It would be a simple matter to deliver raw materials to the outer moon by throwing them loosely into its gravity well. Chunks of delivered material could even be targeted with a fair degree of precision to a specific location on the outer moon, mitigating the need for copious transport over the surface.
The probe once again initiated a thruster-driven trajectory, now nervously aware of its limited fuel supply, intent on reaching the planet and its moons. The probe projected a long arc that would overtake the planet slowly and patiently, as one would do when desperate to survive a trip with dwindling power. Upon nearing the planet it smoothly transitioned to a lunar approach and neared the outer moon. The scout was no longer there. It had explored the outer moon first and then fallen in toward the planet, toward the inner moon. It currently resided on the inner moon's surface and that was where it would stay until resupplied; it lacked the fuel to escape of its own accord.
The probe approached the outer moon and drifted gently down, puffing its thrusters in a precisely coordinated dance so as to maintain stability until finally, with some apprehension, it felt the cold sensation of its feet touching upon lunar tundra. Soft jets and sprouts of dust flared around the probe in uninhibited arcs as the vacuum offered no resistance. Eventually, the landscape settled and all was still.
Once landed, the probe soon began work on the next tasks. Where it had previously sent forth but one space-venturing scout with great trepidation (as it only had in its occupancy a total of three), it now disgorged no fewer than sixteen small vehicles which whirred and rolled across the uneven landscape, each one leaving a distinct trail in its wake. Where the vehicles encountered rocks and ledges beyond their reach, they would project spindly legs, lift themselves up, and gingerly step over‐or on occasion simply leap into the thin gravity and float a respectable distance over some obstacle. Each vehicle ventured radially away and then released sixteen yet smaller vehicles for a total of 256 of the smaller kind.
The whole ensemble was set into constant motion. Some arranged solar collectors to gather energy which would be precious to the collective. Others immediately lay into the bare rock and dust in the vicinity of the landing location, pushing, shaping, flattening, ultimately carving out a small home for the probe and its family. Some vehicles undertook the drudgery of mining, sifting, and refining bare ore. Some went to work on construction, first of the most basic components, such as solid shapes from basic materials and pieces permitting simple motions such as wheels, arms, and other manipulators which might be required for the purposes of repair and upkeep. The complexity of the manufactured components steadily rose as the colony's overall capability grew. It would require the unguided process of natural evolution billions of years to slowly build up devices like these, but the probe and its family could bootstrap the necessary complex processes easily, thanks to their preconceived design. All they had to do was stay ahead of their own demise, repairing and replacing distressed parts faster than they wore out. This had all been prescribed in advance of course and the probe knew that it could survive a certain range of circumstances without falling below the fatal threshold of irreparable entropic decay.
At first, the colony simply grew, both in population and in diversity. In a brief matter of time there were thousands of machines rolling, walking, and hopping about the colony, many of which differed in structure and function from those the probe had originally delivered. Once the longevity of the colony was relatively secure against the assault of dilapidation, a few of the machines were deliberately jettisoned into space. They were targeted toward the planet's gravity well, but in such a way that they could divert their free fall to the inner moon. There they landed, near the original scout no less, and rapidly undertook the development of a secondary colony. As previously described, this second colony's reason for being was for a specific need, new elements which could not be found on the outer moon. As before, a mining and refinement operation was set up and when deliverable supplies were attained, they were themselves lofted upwards, all of this quite easy to accomplish in the two moons' remarkably low gravities, and as intended, these packages impacted (quite violently of course) against the outer moon at a safe but not unreasonable distance from the first colony. The primary colony adjusted its function accordingly, reassigning some machines to the task of retrieving the incoming material packages for use at the main site.
But of course, the purpose of this flurry of activity, in fact the purpose of diverting from solar orbit to the moon in the first place, was not merely to perpetuate the colony seemingly without justification. No, there were far loftier goals indeed. Steadily, the grander purpose came into being as the machines offered some of their services not to the generation of new machines of the smaller and simpler types, but rather to the construction of a set of extremely large machines, each identical to one another and all of them identical to the original probe. Offspring were being born.
This project proceeded fairly rapidly from initiation to completion. Barely a year was required after landing, in fact, a far shorter time than the probe had already spent entering through the system. At its culmination there sat near the probe a row of eleven perfectly identical clones. Gathering enough nuclear material to equip the new probes with the required inventory of nuclear bombs had required mining large areas of the moon. There could be no mistaking the scale of operations that had occurred since the probe's arrival. The moon was now undeniably altered by the probe's presence.
The offspring glimmered in the sunlight, they were beautiful to behold thought the probe as it approved of their semblance with parental pride. But there would be no time for sad goodbyes. Fueled and prepped, each child, now home to three planetary scouts and sixteen of the larger initial vehicles (and each of those containing sixteen of the original smaller vehicles), burst off the surface of the moon with a shudder and drifted with stately aplomb away from the moon, away from the planet in fact as they had erupted from the surface while the moon faced away not only from the planet but also from the sun.
The parent watched as they became smaller and smaller. They would each first bend into a series of confusing arcs around the sun, performing numerous gravity-assist maneuvers until eventually they would fling violently off into the cosmos and fire their primary engines, which consisted of yet another series of nuclear deployments, just as they would use later to brake as they entered a new stellar system. Their departure would take several years in fact and during this time they would be in constant communication with each other and the parent. When they finally escaped the solar system's confines they did not do so in all directions equally, but rather were directed into the hemisphere facing away from the parent's original vector of origin. In this manner the overarching mission was perpetuated, spreading further outward from the original homeworld with each generation, venturing to the next layer of stars. Eventually, one by one, now beyond the outer gas giant, each child initiated a series of nuclear explosions which the original probe witnessed as a sudden trail of white-hot speckles at the edge of the solar system. With that, they quickly accelerated and were gone for good. The probe was once again alone.
At this point, the probe could have left the moon, but there was little reason to do so. The probe was now in a much stronger position than it had been previously. It had an adequate supply of energy and material resources and could conduct its work quite confidently from its current location. Scouts were dispatched not only to the planet below but also to the innermost rocky planet and even to some of the more tantalizing moons of the gas giants. Surveys commenced with the greatest haste and depth, data gathered, observations recorded. Every nuance of the rocky planets' behavior and history was studied and documented. The innermost planet, despite offering a preponderance of water and smattering of land, appeared to be devoid of recognizable life. Theories clashed in the probe's mind as it guessed as to the cause. Most likely, the habitable zone had deviated over time, occasionally frying the world sterile, but perhaps life had simply, per chance, never arisen on an otherwise perfectly hospitable world. It would be difficult to say for certain.
Now, as to the planet directly below however, things appeared to be different. The atmosphere offered tantalizing suggestions of life. The probe had identified these markers long before it even reached the solar system but now it could conduct a more thorough study. The most auspicious markers were atmospheric oxygen and methane. The former was generally produced by life itself while the latter, also a biological byproduct, was short-lived and therefore indicative of notably recent life.
The probe waited and watched. It monitored the planet continuously. It dispatched orbital probes around the planet. Periodically, and with the greatest reservation, it dropped probes all the way to the planet's surface, both land and sea, and even deep into its oceans. These probes would take local measurements, report back to the main probe on the moon, and then close themselves up with thick exterior shells of nonreactive materials, molecularly sealed without a seam. Their interiors transformed entirely, like a caterpillar within a chrysalis, discarding their scanning equipment and transmission apparatus, converting into carefully encoded messages and artifacts. In this state they would await discovery by a sapient species, a day that might not come for millions of years‐or ever.
As expected, microscopic life was discovered on the planet. The probe's elation was practically uncontainable. It studied this life until it completely understood its nature. It continued to observe, waiting, watching. Time passed. Eons passed. Species came and went like clouds coalescing and dissipating over a mountain top. Forms arose, transformed, multiplied. Most vanished.
Eventually, slowly but undeniably, a new species arose, one unlike all previous species, one with a specific kind of potential that exceeded all others. This event was by no means guaranteed. Many of the probe's brethren would not visit a system with viable planets. Of those who did, many would not find a planet on which life would actually arise. Of those who did, many would not find macroscopic life. Of those who did, many would not discover or witness the evolution of new intelligent species.
But this probe was lucky. This new species had the potential to grow beyond its genetic roots. It could learn and then pass that learning to other members, even from one settlement to another on opposite sides of the planet, and even across many-generational chasms of time by the use of writing. It could remember what it discovered and then expand upon that remembrance and do even newer things the next time. But this species' members were still young. They could certainly fail in the ultimate sense, and the probe would absolutely not assist them if that happened. All it could do was watch and wait. Anticipation ravaged the probe's eager observation. It wanted, with famished desperation, to see them succeed, but all it could do was be patient‐yet persistent.
Then, one day...