Boundary: Chapter Fourteen

    "Release of ISM units completed successfully. All units showing on the green."

    "That's the way to do it," A.J. said triumphantly. "Okay, time to get to real work."

    A.J. checked the release pattern and observed that the Faeries were in proper station-keeping mode with respect to each other. Pirate was already moving away to a safe distance preparatory to making its final de-orbit burn.

    That was fine with A.J.. He knew what he was going to do with the Faeries, but he wanted to tweak all the instructions to reflect exactly the situation around Mars. The release had occurred just one hundred and sixty thousand meters from Phobos—a bit less than a hundred miles.

    The Faeries were equipped with electric or, as A.J. preferred to call them, "ion" drive systems. They were low in actual thrust—the optimized designs on the Faeries would, at full power, shove the sensor platforms forward with an acceleration of all of one-fiftieth of a gravity. But the ion drives made up for it with specific impulse ratings that were beyond even the wildest fantasies of nuclear rocket enthusiasts, measured not in hundreds but in thousands of seconds. That made it possible for small objects like the Faeries, which were small enough that A.J. could have picked them up and carried them, to hold sufficient reaction mass to travel significant distances and stop at their destinations. It was critical to give them that ability, since the availability of high-thrust drives such as compressed gas, rockets, or similar approaches was tremendously limited on small probes.

    As everything was on the green, A.J. was going to have one of the Faeries—Ariel—run ahead of the pack, trying to reach Phobos at maximum speed, while the others would take much more leisurely approaches. This would be a test of the Faeries' navigation skills, the precision of his programming and the engineering departments' design work, and of the efficiency and precision of the drive system. At that distance...

    Close enough for minimal orbital mechanics to take part, 1/2at², we get... um... a little over twenty-one minutes, full acceleration for 10.66 minutes and a smidge, flip and decel for same amount of time.

    The other Faeries—Titania, Tinkerbell, Sugarplum, and Rane—would follow at a more sedate pace, getting to their stations around Phobos in a few hours. He worked the precise numbers and course data carefully, then transmitted the orders to the Faerie Fleet.

    "Well, in a while we'll start seeing some action," he said, leaning back and glancing around. "Say, about an hour. Though if you'll watch Titania and Rane's transmissions, you'll get to see the Pirate do its burn and start true de-orbit. They'll try to hold the image as long as possible, another test we programmed in them before we started. That'll will demonstrate how well they can track. Tink's doing some GPR on Phobos before approach, while Sugarplum will be seeing if I can get good returns from Mars with the same equipment. Probably not, but it's worth a try."

    "Where's Pirate landing?"

    "We're combining science and sightseeing. Landing track will take Pirate right down the Valles Marineris, and our target landing site is somewhere near the Melas Chasma. There's a lot of interesting possibilities to be found at the bottom of the Valles, and Melas Chasma has some of the best potential for all sorts of stuff, including mineral finds of various sorts. You'd have to ask some of the others back at Ares for more details. I'm not as up on that as on other things."

    "How long do you think you'll be working here tonight?" Diane asked, curious.

    A.J. laughed. "Possibly all night. Or until the caffeine runs out. I may not be able to control them like a video-game, but watching what they're doing and making decisions as I start getting a real picture of what Phobos is like is a job that can't be entirely left to machines. I don't think I'm going to want to just hand it over to automatics for quite a while yet. Until I know what I'm dealing with, I won't—and the Faeries won't—know what the best approaches are, especially for locating the best places to land the base materials."

    That was, of course, the main purpose of the whole exercise: to survey Phobos with an accuracy and detail never before attempted, including interior imaging if possible, so that the best location for the Phobos Base could be determined.

    "Once the data really starts flowing, no one bother me. I'm putting my earphones on now." He suited action to words, and the exuberant sounds of Tenkuken's Battle For Heaven blotted out any possibility of being interrupted short of someone physically poking him.

    The latter would also be difficult as he had now brought up a temporary cubicle. That minimized disturbance in both directions, since it not only prevented people from casually walking up to him to ask questions, but also screened him from view and at least partially from hearing. A.J. had a habit of talking to himself or playing VR games while waiting for the next round of Real Work. It was only a matter of courtesy to try to minimize the amount of such antics his co-workers were exposed to.

    Initial GPR data was starting to come in from Tinkerbell and Sugarplum. That was what he was currently interested in, but he left the feed from Titania and Rane up so that anyone interested could track Pirate's progress.

    Excellent, the returns were coming in loud and clear from Phobos. It wouldn't be too long before he could start building up an idea of what he had there. Surprisingly, he was actually getting some usable returns coming back from Mars. Well, with the lowest orbit of a natural satellite known—less than six thousand kilometers—he wasn't trying to scan from nearly as far out as he would otherwise. He stored that data for later analysis; it wasn't part of the main project.

    A shadowy image began to build up on his VRD. Phobos' density was known to be very low—not even high enough to be mostly carbonaceous rock. The moonlet's composition was a mixture of rock and ice, or it had large hollows inside. Either was a fairly likely possibility. The theory was that both Phobos and Deimos were captured outer-system bodies, possibly "burned out" comets or something similar.

    Privately, A.J. had bet himself that it was a combination—there would be some hollows, and some ice as well. The latter was close to being a sucker bet, as some probes, notably the ill-fated Soviet Phobos probes of the late twentieth century, had actually detected some water outgassing from the little moon.

    The GPR probes were slowly gathering enough data to start generating a 3-D model of Phobos. The moonlet was roughly oval in shape, with the giant ten-kilometer crater Stickney showing how close the little moon had come to being shattered eons ago. The model was slowly solidifying. Now it was a cloud of gray with just tantalizing hints of structure, but as time went on, he was sure he'd get more out of it.

    Looking at the rest of the feeds, it was clear that he wouldn't have much to do—even just on the thinking end—for another half-hour at least, maybe more. So he keyed the system up to do alerts only when various tasks were complete, and logged on to the Elemental Flame VRRPG (Virtual Reality Role Playing Game) server net.

    After about an hour with no particular alerts from the system, A.J. switched over for a glance. What he saw caused his character Severn Four-Winds to exclaim "What the hell is that?"

    This necessitated some out-of-character explanation and a quick log-off.

 

---

 

    "What is that?" he asked himself again.

    The 3-D model of the miniature moon had become much more solidly detailed, since its ghostly first appearance of an hour or so ago. But the details that could be made out were...

    Peculiar, to say the least. Some areas of the interior were blank, as though the GPR waves couldn't penetrate. That was pretty odd given what was normally required to screen out radar waves. There were rounded and blocky outlines, long curving lines seeming to radiate out from various points, and things that appeared to be hollows of a wide, flat nature.

    A.J. started talking to himself. "Hmm. Well, this is over near Stickney. Result of collision? Maybe. It does radiate outward. I wonder if the other radiative areas coincide with impact events. It's the blank areas that are really funny."

    A.J. wasn't really that knowledgeable with regard to astrogeological dynamics, but to his untutored eye it looked like half-melted conglomerate with crystal inclusions.

    "Which, come to think of it, might not be far from the truth," he muttered. "If the things were outer-system, they must've been something like comets, so parts would certainly be melting at perihelion. And they'd be moving so fast that normally they couldn't be captured by something as small as Mars. So maybe they hit something—something that caused serious melting. Hmm... maybe... what if Deimos hit Phobos, or something like that? I'll have to get one of the orbital mechanics guys to model it. How fast would these things be moving if they came in from out-system, and what would it take to get them captured by Mars?"

    He checked the disposition of the Faeries. Ariel was very close to the surface of Phobos, no more than a mile off. The other probes had stopped about six or seven miles away and were bracketing the nearly fourteen-mile-long moon in a designed attempt to ensure that no point on Phobos' surface would go unmapped.

    "Okay, let's get fancier."

    A.J. considered the arsenal of sensors at his disposal. The Faeries were, in some ways, the most advanced instrumentation packages ever constructed, and they had an awful lot to offer. The primary modality on Earth was sight, so naturally the Faeries were well equipped with cameras. Visible light, ultraviolet and infrared—with their optics sealed between synthetic diamond windows for protection.

    Unfortunately, the real detail he needed—down to a foot or less—he couldn't get at this distance. With a FOV of only sixty degrees, he wasn't going to get much better than five feet or so, even with interpolation and super-resolution tricks. Narrower FOVs would have been better, but the tradeoffs involved had torpedoed that. He'd even had the engineers try a synthetic FOV approach, but that ran into problems with light-gathering capability which would take too long to solve.

    "If only I could use something with decent resolution," he muttered, not for the first time.

    The problem was an old one, dating back to the onset of space exploration. There was almost always a big lag between what technology could do on the surface and what you could get to work up there, with the radiation, vacuum, and other things to cope with. The gap had only gotten bigger in the last decade or so, because with most of the advances hinging on how much smaller and more efficient they could make the gadgets, they'd been getting progressively more sensitive to minor problems.

    Tons of minor problems was pretty much what space handed you all the time. Cosmic rays, outgassing from vacuum, the list went on and on. And there was no corner store on the way to pick up a replacement. That meant that you couldn't afford to use something that wasn't fully space qualified on an interplanetary voyage. For a jump to orbit and back down, maybe, but not across a hundred million miles.

    So, for the Faeries, A.J. was stuck with something not much better than he could've gotten on the street twenty years ago. Barely twenty-five megapixels in the visible, and worse in the IR and UV spectra.

    But there was no point regretting the inevitable. A.J. had IR—near, mid, and far—along with visible and three UV bands. He had GPR, which would certainly be needed. Other frequencies of radio might prove useful, especially if he used the x-ray approach—have one transmitting and the other receiving. Measurement of heat signatures and any chemical emissions would be vital. If there were major caverns or differing composition beneath the surface—which did as suspected seem to be covered with about a meter of regolith—the heat absorption and radiation should show some differing patterns.

    The other real bottleneck was data transmission. Even with all the advances made in other technology, the speed of data transmission from miniature sensor craft like the Faeries was only slightly better than that from old dialup modems. That meant that most processing had to be done on the Faeries. Even one full-size image would take a significant time to send. And this was even though they were relaying through a separate satellite, put there by NASA a few years back, which had as its sole purpose being a communications facilitator.

    The Faeries were advanced. Still, as they had to be space qualified, small, and mobile, their CPUs didn't have anything even vaguely like the power of current processors. With the transmission limitations, they couldn't send back too much data to be analyzed. That had to be reserved for truly unique work.

    Both Tinkerbell and Rane's chemical sensing arrays were showing some water spikes. It was time to try mapping that out and see if he could get some idea as to where the outgassing was coming from.

    It took another hour or so to figure out the optimal search pattern to cover with all sensors, and to ascertain the parameters of the low-power ion burns that each Faerie would have to perform in order to fly that pattern. Finally he was satisfied with the layout of search and sent out the directives. That, of course, triggered a slow-motion acknowledge—repeat—confirm cycle to ensure that all the directions had gotten through and were properly understood. Another hour later, he sent the final "go" confirmation.

    He was tempted to go back to Elemental Flame, but there was business-related Email to answer and other work to do. And this part of the work would take a while.

 

---

 

    A few hours later, the alert pinged in his ear, letting him know that he was receiving data from the completion of his survey pattern. He stretched and dropped the cubicle.

    It was later than he'd thought. There was hardly anyone left around, except Bernie Hsiung over at the Nike construction section, overseeing some of the remote construction work in orbit. NASA had been assembling the material for Nike slowly but surely over the past year, and the work would continue for some time. Like him, Bernie often spent much of his time just keeping an eye on otherwise automatic processes, but it was still necessary to have someone around who had the capability to respond in an emergency.

    "Let's see what we got. Hmm... the internals are still weird, I'm going to have to let the experts argue over this stuff. Water emissions as plotted over time... heating patterns correlations... There's water in there, no doubt, and possibly quite a bit of it. That'll make it a lot more attractive as a base. Transporting water is such a pain. Emissions and internal mapping plus heat signatures... Ah-ha! Two possible emission sources. Ariel, my sprite, come to me! Time for you to earn your living."

    As Ariel was already closer to Phobos, A.J. would use her as his "point man." Ariel would examine the surface up close near the areas where water vapor was apparently escaping from. If he got lucky, there would be a crack or cave in the area.

 

---

 

    After another hour and a half, with Ariel now conducting its survey of the Phobian surface, A.J. headed off for a bathroom break. He stopped off for a candy bar and soda and then headed back. By then, Ariel's transmitters were showing the gray, soft-edged surface covered with fluffy regolith—powdered stone the consistency of flour—up close as it drifted along with a carefully-defined path of examination.

    The first emission site was a bust. There were some cracks, which clearly were the source of some of the outgassing. But they wouldn't have admitted a mouse, let alone a sensor drone the size of a large breadbox. Ariel continued along her way, approaching the locale of the second outgassing.

    As it cleared a small crater ridge, A.J. couldn't quite restrain a triumphal "Yes!"

    Even to eyes still accustoming themselves to the sharp-edged perceptions needed in the airless setting, there was a clearly darker streak that couldn't be anything other than a crack in the surface of Phobos. It seemed to be a crack yawning wide about two meters above the surface in one of the many little cliff ridges that meandered across the little moon's surface.

    "That's why it's not buried in regolith," A.J. muttered to himself. "Horizontal entryway instead of vertical. Hope that doesn't mean it's to some shallow deposit in the cliff."

    As Ariel approached the crack, the automated sensor platform slowed according to prior instructions and directed illuminators into the chasm. It was wider than Ariel by a good half meter in any dimension. Ariel hovered, waiting for instructions. It wasn't permitted to proceed into the interior unless A.J. directly ordered it to.

    There was considerable risk here, of course. The width of the crack was sufficient, but there was no way of knowing how far that ran, and even so the margin of safety was very thin. Piloting would be purely in the hands of the automatics, as there was no way A.J. could react in time to change anything that happened. And an accident could easily destroy Ariel.

    On the other hand, looking at Ariel's sensor data, there was clearly water outgassing from below. Ice had to be present, possibly in significant quantities. And all of his other Faeries were running perfectly. Speaking cold-bloodedly, he could afford to lose one of them.

    The call was entirely A.J.'s to make, since this was his project and no one else could make the judgments necessary. That fact didn't make it all that much easier. In some ways it made it harder, because if something went wrong he could hardly shove the blame away to someone else. But the way A.J. looked at it, finding out as much as possible about Phobos was his mission. He didn't see any reasonable alternative.

    He went through the back-and-forth of order and confirmation once more. This time, once the acknowledgement came through, he stayed glued to his screen. It was true that he couldn't really do anything for Ariel if something went wrong, or at least not immediately, but he still wanted to know right away if something damaged her.

    Slowly, turning on both ion and low-powered chem thrusters, Ariel drifted into the darkness, illuminating it with LED strobes timed with her frame captures to minimize power drain. Tinkerbell positioned itself above the chasm as a telemetry relay, since the farther into rock the drone descended the less signal would penetrate.

    Twenty-two meters in, the dark lateral chasm intersected with another going almost straight downward. A.J., enhancing the view ahead slightly, could see that the lateral one narrowed and eventually ended a few dozen meters farther in.

    "Excellent. Down we go!"

    Ariel could also see the same thing, and despite being orders of magnitude less intelligent than her master, quickly reached the same conclusion. The little probe paused, rotated, and descended into the abyss.

    Fifty meters down.

    With a slow and steady precision, Ariel passed by gray-black rock with occasional tinges of other colors like reddish-brown. The crack descended at a slant, and its irregular walls showed that some sort of violence had caused its opening. That wasn't much of a surprise, of course.

    One hundred meters down.

    Ariel slowed and rotated, seeing a large rock blocking part of the crack dead ahead. It was clear to either side, however, so the automated sensing drone continued its descent, having chosen the lefthand side of the rock to pass by.

    Two hundred thirteen meters down.

    Dark shadows showed on either side of the crack, indicating another cavity or cavern. As Ariel drew level with this new intersection, it was clear that whatever cataclysm had caused this crevice to open had also caused it to cut straight across another long, slender cavern. Ariel hovered at the three way intersection, consulting its own data to decide its course—further down, or into one of the two tunnel-like cavern segments. A.J. did the same, in case he had to transmit to Ariel to abort and take a different route.

    But Ariel made the same decision he would have. The flow of water vapor outgassing was stronger from one branch of the bisected cavern.

    Here, Ariel had a bit more room to maneuver. The tunnel-like cavern, oval in cross-section, was ten feet wide and eight feet high. Strange rippled formations were visible along the walls at regular intervals. A.J. was reminded of the scalloping he had seen in several caves, but clearly these odd shapes could not have resulted from running water over millennia. He wondered if cometary outgassing could have a similar effect.

    Two hundred meters farther along, the tunnel reached a branching. One side turned deeper into Phobos, while the other stayed roughly level beneath the surface.

    Tinkerbell was starting to show a clear drop in signal strength from its sister drone, but both A.J. and Ariel calculated that at least another three hundred meters would be possible before it would be time to decide on whether Ariel would have to go totally solo or not. Once more Ariel selected the path with the strongest H2O concentration—this time continuing along the original passageway.

    Two hundred meters more, and the signal was starting to show some signs of interference. Suddenly the walls fell away on three sides, leaving only one—the side towards the surface—relatively level with respect to the prior tunnel. On Earth, this would be the equivalent of entering a large room in a cavern, with the relatively level side being the "floor." Ariel began a surveying drift around the dim, airless space, which seemed to be huge, something like a football field across. Its light began picking up other cavern exits along the "floor" area.

    A.J. realized how stiff his neck was. He'd been leaning forward, watching tensely, despite the fact that on a VRD leaning forward was just useless. Amazing what instinctive reactions will do. For what must have been...

    Two hours? It was heading for six in the morning! He got up, stretched hugely, and slugged down the rest of his now-warm soda.

    Something nagged at the corner of his vision, which had been concentrated on the mundane for the past couple of minutes. He refocused on his VRD screen and sat down. It had seemed that there'd been a flicker of slightly different color...

    Ariel had noticed it too, apparently. The probe had many subroutines for analyzing images, noticing anomalies, and returning to them. It was slowing and turning around now. Using gyros, it spun in place. Something flicked across the field of view, then stopped and was centered. Slowly it began to grow, with slight flickers of interference across it, as Ariel approached.

    A.J. was barely aware of himself standing slowly, his mouth half-open, hand stretching towards the virtual screen, his hindbrain trying to reach out and touch the image glowing before him.

    Inset into the wall, perhaps a meter from the nominal "floor," was a massive...

    Something. It shone with a brownish-gold luster, undeniably metallic. It was symmetrical, a generally triangular shape with rounded sides and smaller, rounded-sided triangles at each corner. Across its surface, in curved sequences like waves, mysterious black and silver symbols marched in organized ranks.

    Ariel had stopped with the object just filling its field of view. This target lay entirely out of its search parameters, and it was now waiting to be told what to do.

    "Well," said A.J. to the empty air around him. "That's something you don't see every day."