Half Life (18 page)

“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 General’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 toward the open.

“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, recognizing no irony. “Most of the quakes recorded in detail so far have originated at the ice I-ice II and ice II-ice III interfaces well below the surface, 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; none of the marble- to orange-sized drops could be seen drifting downward or blowing around. Not surprisingly, so had the rill trickling along the foot of the cliff. The crew 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 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, even when she was thinking of possible ways to date the latter. Neither had Ginger Xalco, who had been first on the scene, done the testing at the quarry, and 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. That was planned, remember? We didn’t want anything to interfere with rolling 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 edge outside and
below
the sill I made. 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 Colonel Goodall 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 steadiness 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 two Titan orbits, ending about twenty 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 very quickly.”

Maria nodded, pointlessly.

“I want to find out how high this cliff was when Arthur did the area, and whether that height has changed measurably since then. I don’t want you to tell me it’s growing really fast, but I suppose I’d better know if it is. Pay no attention to my feelings.”

“I can answer that now, since the cliff was observed during the ice testing. It was not there at all when Commander Goodall made his investigation.”

“And you never noticed a difference when we started to dig?” asked Yakama.

“The matter was not specifically brought to my attention. Commander Goodall had not yet filed his information with the cross-indexed survey records, so I was not at first including the area in my ongoing comparisons. When he released the files, no one told me to back-check. When the scarp was first noticed and selected for the tunnel site I therefore had 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 really alive in a very different sense from what we had hoped. And check over all the surface imaging we have, from the very beginning, to see whether anything of this sort has been happening anywhere we’ve mapped so far. Have quake waves from this area reached any of the cans yet?”

“None identifiable as such. There is frequent seismic activity at many points on the satellite. 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 more vibration now—Status, I’m at the foot of the cliff. I’m on the west side of the fault, which should be staying put or going down, since I’m at the bottom. 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 plausible, answer to this question. Status alone replied, posing another question which, however reasonable, could hardly have been more annoying to Maria if she had believed it guided by malice.

“How high were you thrown?”

She yielded briefly to the irritation and answered sarcastically, “Seventy-two point three one four millimeters.”

“Center of gravity or boot soles? And how 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 uncertainty depending on the square root of your time-estimate error. With your suited mass of one hundred ten kilograms, the force against your feet must have been—”

“Status, 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 at standard spacing, 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 an 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-millimeter sill went up to about five. The cliff did go up; I should have had the ground drop from under me, if anything. What’s happening?”

“How high were you thrown this time?” and “Is there another cliff somewhere behind you?” came the questions of Status and Belvew simultaneously.

“Maybe your ground was dragged up slightly with the cliff as it slipped,” came another voice, recognizable as that of Emil diSabato. “If the area is being radar-scanned, that can be checked.”

“How?” asked Seichi. “We already know the ground came up, which is all the radar can tell us. The question is
why?
”

“If it rose more next to the fault than away from
it
, it will at least suggest drag forces,” pointed out the lieutenant after a moment. Several people nodded approvingly but invisibly in their quarters; Belvew alone spoke aloud.

“Good thought. Status?”

“The area is not being scanned by anything just now. It is below horizon from the station, and none of the relays is working that area. I advise committing relay units to cover it from now on.”

“Make it so,” answered Maria, “even if we come up with a possible answer right away. To answer Status’s earlier question, I didn’t notice this time, either. I have no way of guessing about the other; you’re closer to the mapping gear than I am. Please get that jet over here! Who’s driving it now?”

“I have it. On the way,” came Ginger Xalco’s voice. “I haven’t seen another cliff either, 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 starting the quake lines?”

“Sow the cans,” ordered Maria before the processor could answer. “I’m going back to dig again.”

“Stay out of there!” Ginger’s 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 Status’s more practical 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 was, she reflected, it wouldn’t be falling far or fast. She could dodge, and even if she didn’t dodge fast enough or far enough the stuff didn’t seem 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? Test of compressive strength on ice blocks had not been encouraging; that was why they were digging instead of building.

What materials could be used? No choice; there was essentially nothing but dirty ice available. It contained small quantities of silicate and sometimes carbonate dust, and often much larger ones of tar; but the process of separating these from the ice, packing it into building blocks, and binding it chemically in some fashion would take far more time than anyone would want to budget—even Status, with human safety in the equation.

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 again 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 Ulan 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 her hand light. Even Titanian outdoor light below the smog was ten stops or so darker than a sunlit Earth landscape.

“I can’t see anything,” she said at last. “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 as a certain landing incident flashed into his conscious memory. The commander gave no answer, and no one else was rude enough to comment. She 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, if you’ve included Heinlein among your classic readings, didn’t know the earth was made in six days.”