Half Life (21 page)

Maria did ask more about changes in the central lake.

“It is now shrinking slowly. It may be relevant that the cumulus cloud normally over it has drifted nearly to the east side of the ring-wall. This is probably why the rain ceased while you were digging; it is now falling partly on the eastern slopes of the feature, and some of the liquid must be draining to the outside.”

“Keep track of the lake’s changes, and the flow in the various streams which empty into it, any way you can. Report any correlation you can detect between the flow and the lake area.”

“And
the depth of deposit of this snowstorm, if we can call it that, over different parts of the crater floor,” cut in Belvew. “You can probably measure it by radar reflectivity.”

“I’ll try that in different wave bands and tell you,” replied Martucci.

Maria scraped the white stuff to one side with a boot until the darker surface showed. “It’s thicker now. There’s just over five centimeters here, if you can use the figure for checking anything,” she reported.

The processor acknowledged the information but didn’t thank her. The commander kept on walking.

“Arthur’s suit hasn’t reappeared, or anything like that, has it?”

“No. It’s a change in the general surface, not just a small spot affecting the average. Ginger could fly there in a few seconds and report what she can see from near at hand.”

“All right.” The pilot didn’t wait for confirmation. “Maria, you’re keeping direction well enough; you don’t really need either me or Pete.”

“Have
you
been watching me too? I thought you were mapping the crater.”

“Between times. It wasn’t just radar that spotted the new faults. Status, I can’t see any difference in the lake, but your memory is better than mine. The cumulus cloud has moved, as you said earlier, and the rain is over to the east.”

“Can you see Arthur’s Pool?”

“Yes, but the color seems the same to me. Look, all of you use your screens. The whole floor of this crater is acting up. There’s a scarp to the southwest that certainly wasn’t there when I arrived, and one extending a little way from the south rim spitting white stuff like the one Maria just visited. No wonder you’ve been feeling jolts.”

“Are all the faults running north and south?” asked Belvew.

“Pretty much, so far. Maybe I’d better land and get Maria off the ground while there’s ground left.”

“There’s no hurry about that,” insisted the commander. “You can’t land in the fog where I am now; it’ll have to be down by the lake as usual, and you’re not to do that until I’m nearly there. Besides, I need to look at the pool—how about more samples from there right now, Seichi? Or have you been keeping track already?”

“There are lots of samples analyzed and filed,” was the answer. “I don’t know the details myself; I’ve been doing them, not thinking about them.”

“Status?”

“There has been a steady increase of complex organics in the pool. Material presumably from Commander Goodall’s body and armor seems to have been diffusing at a rate much higher than the temperature would render likely. Whether this can be the cause of the color change is uncertain; their two rates do not match at all closely.”

Again, if any of the group felt discomfort at this calm report, none made it audible. Once a friend was gone, his body was a data source; one remembered
him
, not his flesh or his face. At least Good-all’s experiment was providing data as he had hoped.

Maria thought a moment before speaking.

“We have a lab at the other pool here in the crater. Does it show anything happening there?”

“No. No significant change.”

“How about the ones near the factory—the one here?”

“The small changes I mentioned earlier. So far of no apparent significance.”

“Check all these change rates, and any which come up from now on, against probable effects of electron tunneling. Anything interesting from the seismic net?”

“Yes. There seems to be a body of liquid below the crater, its horizontal cross section about three times the crater area at one hundred twenty kilometers depth. Its top is at a depth of fifty-three kilometers, its bottom at least one hundred fifty. The resolution decreases with increasing depth, but should improve with time.”

“Maria, get out of there! Get off the ground! That’s got to be a magma plume!”

“More likely water, Gene. Are you asking Ginger to land beside me in this fog?”

“Well, no. But hurry down to the lake, and remember water
is
magma here!”

“The commander has eighteen point five hours before emergency status,” the processor interjected.

“So who’s worrying about your suit?” snapped Belvew. “That crater’s trying to become a volcano. Eighteen hours could see its floor all cut up with faults or covered with fog or with supercooled water ready to freeze around you or a landing ship.”

“Is any sort of prediction possible, Status?” Maria was not quite as calm as she tried to keep her voice.

“Not from present data. The liquid may be the source of the fog, but I have found no trace so far of a feed from the depths to either of the fog sources. The probability that both the fog and the liquid are water seems high, in spite of the lack of ice crystal structure in the former.”

“I can make a guess at that,” lePing cut in. “The gas coming out of that crack is mostly nitrogen, with a healthy trace of methane. Its temperature at the height where the lab is bobbing is about a hundred and ten. I suggest the white stuff is water, carried up from the magma chamber, showing no crystal structure either because it cooled so fast when it got outside that it’s a glass, or because the drops are so small that surface tension keeps them liquid. Either would explain the lack of structure.”

“Maybe it would explain something else,” the commander put in, using a tone that bothered Belvew.

“What’s that?”

“I’ve just been knocked down by another shock—”

“Why didn’t you tell us, or at least Status?”

“Because it’s becoming routine. I landed on my back as usual, and this time rolled over to push up with my hands instead of my elbows. The white stuff is sticking to the front of my armor, I see; and I think it must have been sticking to the back for quite a while. That part has been feeling surprisingly warm for the last half hour or more. I can’t see or reach my back, but I bet the stuff’s there, too. It could be not only acting as insulation but providing heat as it really freezes—crystallizes.”

“Why should it freeze?” asked Martucci.

“Loss of spherical shape would drop the surface tension and the pressure,” said Carla. “Ask Gene why rime ice forms on wings—”

“Of course, but theory later,” cut in the commander. “I’m pretty well covered by the stuff now. It sticks, whatever the cause. At least it’s not interfering with my walking.”

“It’s interfering with something else.”

“What’s that, Pete?”

“I can’t see you anymore—at least, I can’t distinguish you from the rest of the white stuff, from the station. I hope you’re still having no trouble with your trail.”

Maria made no direct answer to this, but gave an order which Belvew naturally interpreted as one.

“Ginger, get down to one hundred meters and circle over the area where I should be. Look for me as carefully as you can without risking the jet with low speed, and if the white stuff is higher than a hundred don’t go into it. Even if you didn’t lose visual contact Carla might be right about the ice. Call out if and when you see me. I’ll keep moving, which should help.”

“Does that mean you
can’t
see your back trail?” asked Belvew. “I can see it, but not as far back as before.”

“Is the fog getting thicker?”

“I can’t tell. There’s nothing
but
the trail that shows at all in this white fluff. It may be heavier fog or faster filling-in of my tracks by wind or some of both.”

“Then travel! Get as far as you can as fast as you can! Try to get out of the fog before you lose orientation entirely.”

“That’s what I’m doing. But there’s a limit to my speed, remember. If I try to run, I automatically jump, and if I jump there’s a very good chance I don’t land on my feet. That doesn’t help either speed or orientation—I hear you, Ginger. You’re almost overhead. I caught a glimpse of you; this stuff can’t be as dense as it looks. You went not quite overhead. I was a little on your right.”

“How long was that before you spoke?”

“Two or three seconds before I reported hearing you I caught the glimpse.”

“Good. I’ll be coming back over that point in sixty seconds from—now. I’ll be heading straight toward the lake.”

“You can still see that? The fog hasn’t blown over it yet?”

“Not enough to hide it. I’m turning. Can you still hear me?”

“Yes. Lucky this isn’t Earth; in a blizzard like this the wind would never let me hear anything else.”

“On Earth we wouldn’t be this worried about you,” snapped Belvew.

“In a blizzard? You’d better read about Scott and Shackleton. Even Earth isn’t always a really nice place. Ginger, you’re coming—
now!
Right overhead!”

“Good. You’re only about thirteen hundred meters from the lake, and should be able to see your way in half that. Can you hold your heading now? Should I go back to filling in geography-time derivatives for Status, or would it be best to keep near you and give you direction every minute or two?”

“Work on the data.” Maria spoke firmly, but not loudly enough to drown out the start of an answer from Gene. He failed to finish the first word, but no one doubted its general flavor.

“All right.” The roar of the ramjets faded, and Maria resumed her hike. Her suit was beginning to feel a little stiff, presumably because of the accumulation of whatever-it-was at the joints. She turned her mind firmly from that phenomenon, and asked Status to update her on seismic information as she walked.

“There has been no major change, though finer details are being added. The new can lines are providing much data in spite of their wider spacing. The magma or water reservoir is as I described it before. I can now trace the crack which is feeding gas to the vent line you examined, but not to the new one the major reported. Six more such faults exist, their lower ends starting at the liquid body. They outline a vertical prism but have not yet reached the surface. Practically all the activity is under the crater; it may be that the impact itself has some connection with what is going on.”

“That would suggest that it’s very recent,” Maria commented.

“Quite possibly. However, there is little difference in the average thickness of the smog sediment inside and out, so either the crater is quite old or the general surface is being reworked much faster than we have supposed.”

“Status,” Gene cut in, “tell us more about those six feeder faults. Where are they? Are they changing—getting any closer to the surface?”

“They are much shorter horizontally than any of the others. Projected upward they intersect to frame the lake and immediately surrounding area in a rough hexagon or, in three dimensions, to place it at the top of a rough prism. I can give you precise edge and depth coordinates if you wish. They are extending fairly rapidly, and will reach the surface in approximately eight hours at their present upward rate. I cannot tell which side of the resulting surface displacements will be the higher, though pressure considerations suggest that the prism will rise; I have no reliable way to infer other stresses from the behavior of the seismic waves.”

“But there’s a good chance that the whole lake area will lift up on a six-sided platform in the next few hours,” the commander mused.

“Or sink. A chance, certainly. It would not be a reliable prediction.”

“What would that do to available landing space?”

“That is already decreasing, assuming a two-hundred-meter landing slide. If these faults extend straight to the surface it will be necessary to land farther to the north or south than before, if we continue to use east and west approaches. Any other run direction would have to be farther from the lake.”

“And from the commander?”

“Yes.”

“Hear that, Maria?”

“Of course I heard it. I’m hurrying. I still think it’s important to get a good look at Arthur’s Pool.”

“Do it from the air! Get out of that crater as fast as you can—Commander!”

“As long as I’m heading near it anyway, let’s not argue. I assume, Status, that the tunnel is no longer of primary importance. How about the general plan to move to the surface?”

“That will have to be dropped until a new settlement site is found. The crater is now unsuitable.”

“And Arthur’s—uh—experiment is wasted?” asked Ginger.

“Not necessarily. The area is supplied with labs, and we can keep track of what happens there unless it and they are all destroyed. Even that could be informative.”

“Then I should land as close as possible to that spot.”

“Not until I get there and tell you to!” snapped Maria. “The jet is less expendable than I am right now; you know it.”

“I know it, but I don’t believe it. Are you able to see any better yet?”

“A little. And you believe it, all right; you just don’t like it. I’m having to move more slowly, though; the knees of this suit are getting stiff. I suppose no one can see me yet; I must be pretty well covered with this stuff, and there still aren’t any bare spots I could stand on for contrast.”

“I’ll come back and make another pass. You should be getting out of that cloud by this time. There—I’m heading where you ought to be. Can you hear me?”

“Not yet. Where are you?”

“Just crossing the south rim, inbound,” answered Ginger. “Half a minute should bring me about over you. I’m at standard.”

The commander waited briefly. She heard the jet in a few seconds, looked up in the hope of seeing it, and just barely succeeded.

“You’re a couple of hundred meters off. I’m to your right—
now!
”

“You haven’t held course, Maria. How about using the wind? It’s still from the west, and I can see the stuff blowing.”

“Too turbulent to be useful this close to the ground. I’d thought of that. Getting knocked off my feet, and I suppose picking up more covering, every few minutes doesn’t help.”