CHAPTER 26.
“Okay, everyone strapped in?”
Joe listened to the affirmations from the others, then put Zarathustra into gear. “Then we’re on our last leg. Next stop, the center of the Earth. Well, way down inside Europa, anyway.”
There was no grumble of a mighty engine, just smooth, silent acceleration as Zarathustra began turning its two-meter wide wheels in slow, majestic synchrony; not only were they in vacuum, but the electric motors driven by the compact nuclear reactor only emitted varying levels of hum.
Joe had to admit to himself there was slightly less visceral entertainment in such a smoothly silent vehicle, but—as an engineer—he approved. Noise was wasted power, or worse, an indication that something was wrong. The last thing you wanted to hear, especially out in space where the parts suppliers were few and far between, was the increasing hum of a worn and failing bearing.
“Hey, A.J., were you able to send the pics and initial data back to Ceres or Phobos Station?” Larry asked.
“Yeah, and I got an acknowledgement that sounded suspiciously filled with squee from the exogeologist types. I’d expect we’ll hear something more substantiative from them in a couple days, at least about your theory, though even the initial responses included people excited about, and people utterly dismissing, the idea that you’re seeing different phases of ice that I guess aren’t supposed to exist at those pressures.”
“I think we may be seeing something that used to be those different phases,” Helen said.
“How so?” Larry asked.
“Well, let’s say your other phases aren’t supposed to exist when they reach the surface. If the conversion to the other phase isn’t something instantaneous—and at these temperatures I’d think not too many things are instantaneous, and the other conditions are what you describe, I’m imagining you’re looking at something more in my field.” Joe could see her smile when he glanced in the rearview; he could also see Larry’s momentarily perplexed expression.
“It’s a mineral equivalent of a fossil, Larry. The shifting phase of ice lost molecules of ice as they shifted, but new molecules were deposited in the same location. Eventually, you end up with a structure of standard ice that’s in the same shape as the old structure of a different phase of ice, just as a bone starts out made of, well, bone, and is converted over millions of years into a different mineral composition.”
Joe maneuvered Zarathustra slowly around a slender column of feathery, green-brown tinted ice that looked something like a feathered vine as he heard Larry’s grunt of understanding. “That…that might just work. It’s sure a good alternative to multiple co-existing phases of ice that shouldn’t be present. Bet we can get a few papers out of this, either way.”
Maddie, seated in the copilot seat to his right, chuckled. “With everything we’ve seen on this journey, I wouldn’t be surprised if you had enough to write papers until you both die of old age.”
“What an exaggeration,” Helen said. “I’ve only recovered a small handful of obvious fossils and a few other possibles. Why, I could hardly manage three dozen papers on that.”
“Funny,” A.J.’s voice said. “We still call them ‘papers’ though they’re almost never on paper anymore.”
“Language changes, but phrases stick around for a long time,” Joe said, slowing as he approached a tilted area of the tunnel. “I still hear people say they’re ‘running out of steam,’ when I’m not sure any of them have ever seen a steam powered vehicle. In fact, I’m not sure I have except in old videos.”
“I like your theory, Helen,” Larry said, continuing the main thread of conversation, “and we also don’t know what effect the various minerals in solution might have for replacement or crystal formation. If some of them crystallize first, they become nucleation sites for other crystals, including water.”
“But,” Anthony LaPointe’s voice broke in, “additional dissolved minerals should lower the freezing point. Would that not affect the formation of other phases of ice?”
“It might. But it’s not really the temperature, but the pressure. Even at the bottom of Europa’s ocean, if it’s a hundred kilometers deep, the pressure won’t be even as high as it is at the bottom of Earth’s ocean trenches. Now, I seem to remember that under some conditions you can recover several other ice phases at standard pressure, but…”
Joe tuned out the more technical discussion as the icy road ahead got rougher. Zarathustra’s tires were a unique polymer blend, nanotextured as well as formed with carefully-designed tread patterns to maximize grip on icy surfaces, but even that sometimes wasn’t enough to prevent skids and slips on ice in an environment with an eighth of a gravity and at temperatures that made the ice more a solid rock than ordinary frozen water.
Zarathustra skidded slowly as he braked into a turn to avoid another column; the huge rover barely brushed the column, which held firm—and then seemed to explode in a shower of shrapnel as he edged Zarathustra by. “Holy crap!”
Other shouts of consternation echoed in the rover’s cabin as he brought Zarathustra to a halt. What could possibly have caused that? “That column just blew up, Larry, A.J., everyone.” He scanned the telltales and checked the feeds coming from the onboard sensors, slowly relaxed as he saw no sign of damage. “What the hell caused that? Are some of these formations so unstable they’re explosive?”
Larry scratched his head. “That…doesn’t seem likely. Even if there’s a reasonable concentration of oxygen in the water below, like some theories claim, it’s not going to be available for an explosion here. And at these temperatures…”
He trailed off suddenly, then gave a deep chuckle. “When, exactly, did the column blow up?”
“I was almost past it, though we were just about brushing on the righthand side.”
“Which means it was exactly next to the main radiators.”
Joe slapped his forehead, feeling more than a little like an idiot. “Temperature differential?”
“Temperature differential. What with our environmental requirements and the reactor itself, we’re radiating a lot of heat into this environment. And at that range, you’ve got maybe three, four hundred degrees of differential between the one side of the ice and the other. Wouldn’t have too much effect on larger chunks, probably just take chips off them, but on something that long and thin…”
“Yes, that would do it,” Madeline said, nodding. “I’ve seen really cold ice-cubes shatter pretty energetically when you drop them in water that’s just warm.”
“It’s not quite that bad,” Joe said, checking the readings. “At this depth, we’re reading a balmy minus one hundred ten. Still more than enough.” He started Zarathustra moving again.
“If we’re radiating that much heat,” Helen said after a few moments, “are we endangering what we’re seeing?”
Larry frowned. “Probably, at least to some extent. These regions have never encountered the temperatures we bring with us. Hold on.” A pause, during which Joe got them over a ridge. “Yeah, it’s affecting the area. We parked in a fairly wide area of the tunnel, and examining the formation pictures before and after I can see they changed or eroded overnight. Not terribly much, but if we stayed there for a few weeks there’d be quite a bit changed. On the plus side, we are dealing with water ice, which has a high heat capacity compared to a lot of things, so it’s not like dealing with spires of solidified nitrogen or something.”
“Then we cannot stay down here long,” Madeline said reluctantly. “Since we are nearing our goal, I see no point in not reaching the end before returning; we will be emitting essentially the same amount of heat as we pass the same areas whether we do so now or a day or so hence. But we can’t spend more time down here than a day or so, or we risk causing significant damage to structures which may be unique.”
“I wouldn’t be surprised if there are at least one or two similar regions,” Larry said. “I suppose we could have just happened to land near the one and only example, but I would bet heavily against it. Still, you’re right. If there’s anything worth seeing at the end, and it’s big enough, we could stay there a few hours, but we should make tracks back as soon as we’re done.”
The thought did put a slight damper on Joe’s enthusiasm—he’d hoped they’d have time for some actual research—but he couldn’t argue the point. All those beautiful formations they’d seen couldn’t survive their presence for long; staying nearby would be like observing sugar sculptures while misting them with water. “Well, we’re almost there. I can also try to drive us out a little faster than we came in.”
“Dunno if that would help much,” A.J. said. “Move faster, you’re cranking the generators more, which means more waste heat per minute. Maybe it would, though. But even though you’ve been down the path once, driving faster in the other direction might be the key to a disaster. I think we’d all agree that while we want to preserve all the scientific data we can, we don’t want to do it at the expense of any of you.”
“Exactly,” Madeline said. “No, Joe, take the same caution going out that we did coming in.”
“Okay. Just felt I should offer.”
A few minutes later, Zarathustra rolled smoothly into a moderate-sized cavern. To the left and right were a profusion of icy formations—hexagonal branching plates, feathery columns and spines, interpenetrating cubes. The far wall was mostly bare, however, a smooth sheet of white frost with slight tinges of other colors.
“End of the line,” Joe said. “We’ve come as far as A.J.’s map says we can go. There’s a lot of formations here that we could do some quick sampling and examination of.”
“Where will you park?” Maddie asked.
“Not near either of those walls,” Joe said. “The far wall’s got pretty much no formations on it, except up on the higher edges and some on the far sides, so if I park there we should be endangering as little as possible.”
He suited action to words, trundling Zarathustra over the now fairly smooth floor towards the far wall; as there was enough room, he turned around and backed towards the wall, so that Zarathustra would be already facing the exit when they left.
As he backed towards the wall, the high-intensity rear lights shone directly on it, and with a few meters to go, Joe suddenly caught sight of another set of glints, glints and shadows within the wall he was approaching.
He slammed on the brakes reflexively, and that would have been more than enough; he’d intended to stop a meter or so short of the wall anyway. But just as he did so, a small tremor jolted the ground, three of Zarathustra’s six tires lost contact with the ice, and the rover slewed sideways slightly, bringing the lefthand radiator into direct contact with the white-crystal ice.
With a silent detonation the entire wall shattered like crystal struck with a sledghammer, fragments ranging from the size of daggers to boulders raining down. Within Zarathustra the slow-motion cascade of shattered ice sounded at first like a quiet tapping hiss, then more insistent rapping as though a dozen elves were knocking on the hull, building to a rattling cacophony that nearly deafened all within. Subsidiary blasts of pulverized ice showed as larger chunks hit the radiators.
“I think you’ve disturbed the environment,” Larry said dryly, as the last of the chunks banged off the hull. “I hope…” He trailed off, as Joe slowly unstrapped from his chair, eyes fixed incredulously on the rear window which a moment before had shown shadowed white blankness.
Beyond the wall was an immense space, so huge that the brilliant lights of Zarathustra could not even begin to illuminate the entirety of the cavern. The floor descended in regular, rippling terraces to a smooth, ballroom-flat area that extended beyond the lights’ range. In every other direction—walls, ceiling, even parts of the floor set away from the descending terraces—were icy growths of impossible delicacy and size: feathery draperies of arching beauty that would have shattered of their own weight on Mars, let alone Earth, stratified columns that seemed to have telescoped from floor to distant roof, scatterings of hexagonal plates embedded in clear ice like the honeycomb of some inconceivably huge bees, fairytale spires rising from the floor and dusted with incredibly thin and diamond-sparkling needles of ice that reflected the light like a shining halo, a thousand wonders of translucent and diamond-clear and ripple-tinted crystal that held the entire crew of Zarathustra in complete and utter thrall for long moments.
Finally, Joe shook himself and resumed his seat. “I think,” he said, “that we’ve found a place I can park.”