Complete Short Fiction, page 278
On the other hand, if Maria herself seemed likely to be too far from the landing site when the jet came back, so that she might not reach orbit while her suit supplies lasted, the computer would foresee that and firmly recommend return before she got anywhere near the rim. Suits could not yet recharge on the surface. None of this was conscious thought for Maria at the moment, just background knowledge.
Status.
Just north of one of the small tar fans was the entrance to the tunnel she was digging. It was about two meters high, with a five centimeter sill of piled ice sand across the bottom, and about as wide. Equipment as well as suited people would have to get in eventually. It was dug in the clear, nearly pure low-pressure ice—ice I—which formed the lower two thirds of the cliff under the sediment layer. The latter was thinner than average here; one might use that to date the impact which had formed this crater—no, it was gone from the cliff foot, and there was no way even to guess how much the stuff on top had been affected by the same erosion. Or why there was a difference—never mind that now, Collos.
Back to work. Research and fun later. She stepped across the clear ice and the rill of liquid methane running southward along the foot of the scarp—it was raining—picked up the chipper, and turned it on. It hummed obediently, so she descended the twenty meters of completed tunnel and pressed it against the end wall. It resumed shaving and swallowing ice, and spitting the resulting powder toward the tunnel mouth behind her.
The group had learned; this machine had a double head and counter-rotating blades. It did not try to spin her in either direction no matter how hard she pressed against the wall.
She was getting more skillful in its use, too. It could only exhaust straight back, but she was now able to aim the heads most of the time so that “straight back” not only missed her suit but blew the dust all the way to the tunnel mouth, and she only had to pause every ten or fifteen minutes to clear her exit path. Her relief would bring a newly grown blower to handle that job, she had been told; most of the survivors could still do improvisional programming on equipment “seeds”. The new factory now growing near the central lake nine hundred meters to the south even had locatable roots, a quality omitted from its predecessor. In two or three weeks it should also have produced a remotely controllable tunneler, and Maria and the others could get back to their proper, planned work.
She was angling the tunnel downward, and already had seven or eight meters of ice and sediment overhead. Human beings under Titanian gravity, she had noticed, seemed not to feel much fear of cave-ins, a comforting if unrealistic attitude. It had started to change recently as ground tremors became more frequent, but she did her best to enjoy it. Details of the planned Base had not yet been completely worked out, but it would certainly have to be deep enough to be walled and ceiled by clear, seamless ice even if they decided to change to Titanian air pressure. The fallen smog layer was about as strong as sand except where methane reins had caused it to crust. While sturdier at such spots it would still not make a reliable ceiling even in local gravity and with balanced pressure.
The need for the downward slope had therefore been obvious. That for the sill at the tunnel mouth had not. The stream along the cliff face was intermittent, and had been dry when the digging started. Now there was methane sloshing around Maria’s feet as she worked. Blowing this outside with the chipper had seemed an obvious solution when the liquid first trickled in, but the drops wouldn’t fly as far as the denser ice chips in the heavy air. They settled to the floor and ran back downhill.
She had taken care of most of the problem by digging a sump a few meters back but this, unfortunately, had meant plastering some of the ceiling with an ice-methane mud which always chose the moment she was underneath to drop by handfuls onto her helmet. Water still did not bond closely to hydrocarbons, though the digger was also an effective blender. Maria still spent some of her work time distracted by thoughts on which of this new crop of unexpected trivia might turn out to be lethal.
She did what she could about that, reporting every action and its result to Status though she put more faith in human imagination than in the data processor to provide warnings.
“More vibration!” she called suddenly. Belvew replied.
“Could it be your chipper getting out of balance, or biting deeper with one head than the other?” Alternative hypotheses were a moral imperative on Titan; being too sure too soon—the Aarn Munro syndrome, as some classicist had long ago named it—had proved a fruitful source of trouble.
She turned off the machine as the most obvious way to test this one.
“Right, I guess, but—no, there it is again.” She reactivated the digger and pressed it once more against the ice. The quivering stopped briefly, then resumed. “It’s not that.”
“Local quake? Titan still has plenty of tectonics, we know.” This time it was Pete Martucci.
“Wouldn’t the seismometers be telling us?”
“Not necessarily,” Status’ calm voice answered. “Seismic events have occurred often since the first can line began reporting; and are presumably regular Titan phenomena. However, the outer ice layer does not carry waves as quickly as silicate rock. None of the lines is close enough to Settlement Crater for an epicenter under that point to be recorded promptly. I suggest you leave the tunnel until that idea can be checked, Commander Collos.”
“But that’ll delay—”
“Not as much as would the collapse of the tunnel, and it would be better for the overall project if you observed such an event from outside.”
“Yes! For Reason’s sake get out of there!” snapped Belvew. “And if you want to remind me that Arthur left you in charge, do it as you run!”
“Why didn’t you mention the quakes before we started the tunnel, and if you knew about them why did you plan an underground Station at all?” interjected Yakama. It was obvious to all, including the machine, whom he was addressing.
“Because no temblor has yet approached an intensity likely to damage the sort of structure we plan, and—”
“Then why did you order me outside?” snapped Maria, without slowing her pace back to open air.
“Because theory must yield to observation, and this is our first chance to observe the actual effect of such an event on anything like the proposed structure.” No one tried to argue this point; Maria changed the subject.
“I’m outside,” she reported. “The rain seems to have stopped, if that matters to anyone.”
“It may be relevant,” Status commented, apparently recognizing no irony. “Most of the quakes recorded in detail so far have originated at the Ice I-Ice III interface, and redistribution of surface mass caused by rain, with resulting changes in deep pressure, could well be the basic cause. The correlation is statistically—”
“All right, keep track of it. When can I get back to work? I’m still using oxygen you know.”
“I know. It will take nearly twenty minutes for a wave front starting at your coordinates to pass enough network stations for reliable analysis. Are there any new local data which you could report? That might speed a possible decision.”
Maria looked around thoughtfully. As she had said, the rain seemed to have ceased. So, not too surprisingly, had the rill trickling along the foot of the cliff. She had already dismissed this as just part of the drainage pattern which returned most of the crater’s rainfall to the central lake and made Settlement Crater a nearly closed weather system.
Water ice is too polar to be at all soluble in liquid methane, and Maria had not been surprised that the temporary brook showed no signs of having cut into the foot of the cliff, not even when she was thinking of possible ways to date the latter. Neither had Ginger Xalco, who had been first on the scene and had started the tunnel. Now something she didn’t remember seeing earlier caught Maria’s eye, and she looked at it thoughtfully for a moment.
“Ginger!”
“Yes?”
“When you started to dig, I know there was no stream along the cliff, so there was no reason to make a sill. Did you start the hole right at the bottom of the face, or a little bit up?”
“At the bottom, of course. We agreed on that, remember? We didn’t want anything to interfere with bringing heavy stuff inside. It was just starting to rain when you took over, and you had water—I mean methane—inside in two or three minutes. That’s why you had to make the sill.”
“That’s how I remember it. Now I see about three millimeters of cliff outside and below the sill. Status, how fast could that stream eat its way down—remembering that it doesn’t seem to undermine the cliff or cut the ground at all?”
“It couldn’t.” Two voices besides that of the computer answered simultaneously.
“Then what, besides a three millimeter lift of the cliff itself since I built the sill, could have happened here?”
Neither Status nor anyone else answered that one. Maria thought furiously for some seconds—no more furiously than any of the others, but she spoke first.
“Status, what summary do we have on this crater? And how far back does the information go?”
“I assume you mean in time,” the computer answered. “There is very little, actually. The area had not been covered by the regular mapping program when Commander Goodell first centered his attention on it. His original data came from jet-based pictures taken from altitudes too high for good data, because of poor air transparency and the jet camera resolution. When he became really interested in the site he secured more material from orbit without calling either your attention or mine to it; I now find that I have good pictures over a period of about one Titan orbit, ending about eighty hours before his landing. I cannot show you these where you are; you would have to come up here or at least board a jet. I can, of course, give verbal and numerical descriptions. If someone will make appropriate requests I can present current data quite soon.”
“What I want to find out is how high this cliff was when Arthur did the area, and most important, whether that height has changed enough to measure since then.”
“I can answer that immediately, since I have your description of the cliff. It was not there at all when Commander Goodell made his investigation.”
“And you never noticed the difference when we started to dig?” asked Yakama.
“The matter was not specifically brought to my attention. Commander Goodell had not filed his information with the regular survey records, so I did not include it in my ongoing comparisons. When the scarp was first noticed and selected for the tunnel site there was therefore nothing to compare it with.”
Maria cut in. “We understand that. Now, Status, do everything you can to make sense out of the fact that the cliff is here now. Especially, tie it in as closely as you can with all the seismic data we have; it looks as though Titan may be alive in a very different sense from what the Project had in mind. And check over all the surface data we have, from the very beginning, to see whether anything of this sort has been happening anywhere we do have records for. Have quake waves from this area reached any of the cans yet?”
“Nothing identifiable as such. As I said, there is frequent seismic activity. What you ask will take some time—not much for record search, but possibly a great deal for comparison and analysis.”
“Just a moment. Another question. There’s some more vibration—Status, I’m at the foot of the cliff, on the side of the fault which should be staying put or going down. It’s the cliff which should be rising. Why was I just tossed into the air?”
The living listeners, the ones with imaginations, said nothing; each was furiously seeking a reasonable, or at least possible, answer to this question. Status alone replied, posing another question which could not have been more annoying to Maria if it had actually been guided by malice.
“How high were you thrown?”
She yielded for a moment to the irritation and answered sarcastically, “Seventy two point three one four millimeters.”
“Center of gravity or boot soles? and how was that measured?”
“Disregard that datum.” She had command of herself again. She was also back on the surface, still standing, and for a moment thought of using her time off the ground to calculate the height she had reached. Then she realized she had no accurate estimate of that, either. But even a guess would mean something, she reflected. “I was off the ground about three seconds. That’s only an estimate.”
“Were your legs straight, or equally bent before and after the event?”
“Straight. I was simply standing when it happened.”
“Then you were lifted approximately one hundred fifty-one centimeters, with an uncertainly depending on the square root of your time estimate error. With your suited mass of two hundred ten kilograms, the force against your feet must have been—”
“Dammit, I don’t care about that. I’m on the down side of the cliff. Why was I thrown up?”
Belvew beat the computer to a response. “Has the three millimeters of cliff under the sill changed?” Maria had to pause to check before answering; being hurled into the air, even when one comes straight down again in practically the same place, is disconcerting.
“It’s about the same. I only estimated it before.”
Status cut in. “I advise setting up two more lines of seismometers each one hundred kilometers long, at right angles to each other, and intersecting as close to the center of Settlement Crater as may be practical. There are enough cans already manufactured to do this.”
“Where?” asked Belvew.
“Aboard Crius,”
“Which is headed up to you. Are there any on Theia?”
“Enough for about half of one of the lines I suggested.”
Maria made an instant decision, and used her authority. Like the others, she needed no explanation why Status wanted the on-the-spot deep scan. “Get Theia here as fast as possible, and have it make the two lines with four times normal can spacing. You can get lots of information, even if resolution won’t be as high—blast! I just got tossed again. We are really having quakes. And this time the three millimeters went up to about five. The cliff went up; I should have had the ground drop from under me, if anything. What’s happening?”
“How high were you thrown this time?”
“Is there another cliff somewhere behind you?” came the questions of Status and Belvew simultaneously.
“I didn’t notice this time, either.” Collos took the machine’s question first. “I wasn’t expecting it. Get that jet over here! Who’s driving it now?”
“I have it. On the way,” responded Ginger Xalco’s voice. Belvew repeated his question.
“I haven’t seen one, but if I’m on the high side and it’s any distance away I wouldn’t expect to. Which is more important, Status? Going west to find another fault, which is probably there but probably not important, or getting back to work on the tunnel?”
“Stay out of there!” Ginger and Belvew’s cries were almost together.
“Check the tunnel as far as you can see without actually entering it, for evidence of new faults,” was the computer’s contribution.
Maria glanced toward the top of the scarp, and then to each side along its foot. Neither ice nor sediment seemed to have been shaken down by the recent shocks; and if anything were, she reflected, it wouldn’t be falling far or fast. She could dodge, and if she didn’t dodge fast enough the stuff wasn’t likely to be dangerous. They did need to know as soon as possible whether the whole idea of an underground station would have to be abandoned. Could they build any sort of surface structure? How? From what materials?
The choices were ice and smog sediment—tar dust. She was distracted from the problem for a moment as the ground trembled again, not hard enough this time to throw her clear of it. Aftershock? Was the show nearly over? Would Status be able to decide about that even with the new lines in place?
The computer was not, of course, infallible; should she follow its rulings—no, suggestions—uncritically?
Of course not; but she couldn’t act without them, either. She resisted the urge to call Ginger to hurry; Theia was, she was sure, at full thrust already.
“Any faults in the tunnel?” Belvew’s voice recalled her to the present.
She approached the opening, and, after a moment’s hesitation, took a single step inside. At least the sediment at the cliff top, which seemed more likely than the ice to be knocked free by any more temblors—it was a dirt-compared-to-rock situation, really—wouldn’t hit her here. She examined the tunnel walls carefully with the aid of a hand light. Even Titanian outdoor light below the smog was seven or eight stops darker than a sunlit Earth landscape.
“I can’t see anything,” she said at list. “The walls aren’t perfectly smooth, but the only grooves I can see are along them. I must have made them myself with the digger.”
“You should resume digging,” said Status calmly.
“No you don’t!” Belvew almost screamed. Maria frowned silently for a moment.
“Sorry, Gene,” she said. “We need the new station.”
“Not the way we need live brains!”
“I think it’s safe enough.”
“How safe is safe enough—oh.” The man fell silent. The commander gave no answer, but started back down the tunnel.
“You wouldn’t have let me do it.” Gene’s voice was much quieter.
“You don’t know that.” Maria resumed work with the chipper.
“Nehemiah Scudder didn’t know the earth was made in six days.” Belvew omitted the “he just believed it” part of the remark; there was no point either in being grossly insulting or leaving himself open to a devastating retort. Maria probably wouldn’t have made one, but still . . .
The rest of the group were all listening, after all.
