Portal-eARC (20 page)

“As we have also already found one layer with extremely interesting xenopaleontological significance, Dr. Helen Sutter was also an obvious choice. That covers the obvious scientific members of this expedition. With two other slots available, as we had agreed on four people, no more, I felt that I was one of the other obvious choices. Not to sound full of myself—”

“—but you’d have every reason to be,” A.J. interrupted. “You’re our best all-around everything, really, and if you run into anything you don’t expect down there, well, you’re the one who’s going to deal with it better than anyone else.”

Joe could hear that Maddie was pleased with the compliment. “Thank you, A.J., and that’s my basic thinking.”

“And your last crewmember?”

“That’d be me, General,” Joe said. “There should be at least one engineer with them, I know
Deep…
er,
Zarathustra
better than anyone else except maybe Mia, and Mia’s supervising all the work on
Odin
.”

General Hohenheim gave a grunt of assent. “That all sounds quite sensible. Have you found the precise access location?”

“
Kwai Chang
located the thin crust area yesterday,” A.J. said, while pushing. “At its thinnest it’s no more than half a meter thick. Maddie’s already calculated the charge points and from the one side of the hole I think we’ll have a drop of no more than two or three meters, which
Zarathustra
will handle just fine in this gravity. After that it should be all clear. If we run into an obstacle we can’t clear, well, okay, that’s that, but
Jiminy
didn’t find anything when I sent him through before.”

“Very good. Then once
Munin
has safely brought the drive nozzle here, I would expect you shall begin this exploration?”

“That is indeed the plan, General.”

Joe had to admit, as he saw the nozzle slide a few meters nearer
Munin
—now only about thirty meters away—that he was excited by this prospect. Oh, sure, it was just an icy tunnel, really, but he’d be descending
into
a moon. And there might be more exciting finds; Helen had uncovered at least six pieces of something Bemmie-like, and other as-yet unidentified fragments of something that might be animal, plant, or something else. He remembered those long-ago times on Earth, driving or walking along weathering cliffs and arroyos, trying to spot something just a tiny bit different that might mean a fossil.
And we just might be doing the same thing here, six hundred million kilometers from Earth!

Chapter 25.

“My
God
this is beautiful!”

It wasn’t the first time she’d expressed those sentiments in the last hour, but Helen couldn’t restrain herself, and the others didn’t seem bothered.

The walls of the huge, generally triangular tunnel reflected the lights of
Zarathustra
in a blaze of color, as though coated with layers upon layers of diamonds. Stripes of color—brown, black, greenish, red-orange—ran through the walls at different angles, but the walls themselves shimmered in hues of transparent glass, glacier-blue, sea-green, with irregular surfaces that seemed faceted on every side. Some were like cubes, others hexagonal plates layered upon each other, and in other spots the wall shone pure white like new-fallen snow at high noon, or cast tiny sharp-edged shadows that revealed feathery, curling structures.

“Looks almost like something dissolved away parts of this wall,” Maddie said quietly.

“Not dissolved,” Larry answered with a grin, taking picture after picture from the data stream. “A process much more sublime than that.”

Joe failed to restrain a snort, even as Helen winced, knowing what Larry had set in motion. “Enough of your vaporing, Larry. What’s your triple point?”

“Deposit yourself back in your chair and I’ll explain. It’ll be a gas.”

“
ENOUGH.
” Maddie’s voice held a tinge of amusement, but only a tinge, and there was more than enough authority with it. “I swear, every time I think you’re getting older, Joe…and Larry, stop encouraging him. So you’re saying that the…worn and eaten-away appearance here is from the ice subliming away in vacuum?”

“Partly, at least,” Larry answered.

“But don’t you usually end up with a dark, even blackish, surface that way?” Joe asked, more seriously. “I seem to remember something about that with comets. And Ceres had a lot of blackish ice.”

“Normally, yes. But…well, first, let’s face it, we’re still learning stuff about the solar system. Every time we’ve sent an unmanned probe somewhere, it’s sent back information we didn’t expect. Every place we’ve gone, something weird’s shown up. Why should we expect Europa to be any different?

“Anyway, we’re getting fairly deep inside Europa now. We’ve come, what, almost 20 kilometers, so we’re down well below where
Athena
holed-through. Pressure on the ice is getting significant, and—much more importantly—up until
Athena
came through and we dropped
Zarathustra
in, this was sealed up.”

“You think that makes a difference?” Helen asked.

“It might. You see, if this is a sealed chamber, or was, it’s more like a crystal chamber on Earth, or a geode, than something exposed in a larger chamber with an outlet. Remember that A.J. detected a wash of water vapor come up when
Athena
broke through? I think there was
pressure
in here. Not much, you’d call it vacuum on Earth, but a lot more pressure than anywhere else on Europa. The ice sublimes slowly over millions of years, and redeposits elsewhere. As we get farther down, remember, the temperature goes up. It’s already noticeably warmer where we are than on the surface—though humans like us wouldn’t notice. So that might mean we’ve got more water vapor coming up from below, filling this space.

“And we’ve got more pressure on the ice itself, except at the very surface, which means that there’s probably several phases of ice here. Hexagonal stuff is normal ice, Ice I
_h
, but some of those things there look more like octahedrons, which would be Ice I
_c
, and over there,” he pointed to a set of squarish-looking crystals stacking up like a deck of cards given a half-turn, “those look rhombohedral, which would indicate Ice II. No one’s really had much chance to study how a complex system with multiple ice phases like this could interact, and what we’re seeing here could be a combination of crystals left after one phase sublimed, and crystals deposited later on.”

“And, of course, there’s whatever impurities we’ve got in the walls.” He gazed at the rippled colors passing by. “I’m restraining myself from demanding we stop only because I want to see what’s at the end of this ride as much as the rest of you.” he added.
“After
that we come back and do some ordered and systematic sampling.”

“Of course, Dr. Conley. And whatever causes it, it’s lovely,” Madeline said. “A.J., I’m surprised you didn’t draw our attention to this.”

“Well,” A.J. answered after a pause, his voice sounding slightly tinny through the multiple relays they’d left in the tunnel to assure transmission, “I’d
sort of
noticed that there were some neat formations, but I was really more interested in scoping out the extent and accessibility of the tunnel. And looking at the pictures my Locusts brought back…well, they’re okay, but they don’t have the impact yours do. Remember, the Locusts were designed for close up work mostly, and don’t have the top-quality ranged imaging systems. The pics you’re sending back are gorgeous.”

“How are things topside?” Helen asked.

“Other than missing you?” he said, his sharp smile showing in the upper left corner of her VRD. “Pretty good.
Athena
’s performing perfectly,
Munin
docked successfully and they’re transferring the nozzle now. Everything’s stable up here, no emergencies, not even a
hint
of emergencies, actually, so you don’t need to worry.
I
just have to worry.”

She shook her head, but smiled. “Everything’s fine here too, A.J.”

“Found any fossils?”

“Nothing obvious yet,” Joe answered, turning the wheel of
Zarathustra
slightly to maneuver around a large chunk of ice sticking out into the passage. “We didn’t see anything when we passed the rough level of the deposit that Helen was looking at from
Athena
’s old bore, so either it didn’t extend that far out, or the layers were shifted.”

“I’d guess the latter,” put in Larry. “The patterns on the walls and floor that we can see through the—presumably—sublimed and redeposited material seem to at least tentatively confirm the theory that this passage is a void left by jumbled blocks of ice, which would mean that a lot of the surface might
seem
like a continuous thing, but it’s a scrambled mess under the surface, like breaking up ice on a pond and then letting it re-freeze.
Whoa!
”

Helen echoed him with an inarticulate cry as
Zarathustra
tipped forward and dropped into freefall for a heartstopping second, before bumping (surprisingly gently) back to a driving position.

“Don’t panic,” Joe said calmly, ignoring the consternation in A.J.’s sudden spate of inquiries. “Went over a shelf and dropped a few meters. I knew it was there and it’s not like rough riding on Earth.” Joe made sure
Zarathustra
’s two manipulator arms were still firmly locked in position, tucked under the forward part of the rover where they were least likely to get in the way or be damaged by anything projecting.

“So if it’s a matter of subliming, temperature, and pressure,” Madeline said, picking up the prior conversation, “we should expect more and larger formations as we get farther down?”

Larry looked suddenly cautious, with an expression Helen knew from her own mirror during the original
Bemmius
research: the look of a scientist trying to avoid making any direct statements on something that they haven’t enough data about. “Well…
if
I’m right on that, and it’s very wild speculation, and we haven’t gathered nearly enough data…well, yes, I’d expect we’ll see more as we go down. But like everything else in the solar system, I won’t be surprised to be surprised on that.”

Helen chuckled. “A perfectly scientific way of putting it, Dr. Conley,” she said, and then checked her time and map indicators. “At this rate, we can falsify or verify your prediction in a few hours. We’ve got, what, about fifteen kilometers to go?”

“Fourteen point two,” Joe said, “According to the sketchy map data A.J. put together. At that point the passageway appears to end. But it’s going to get a little rougher and a little slower than you think.”

“So tomorrow?”

“Yes,” Madeline said firmly. “I’m not going to let us drive on for more than another two hours, and we will not reach the end before then. We’ll stop and rest—and yes, go out and take a few samples, since we’ll already be stopped,” she said, seeming to be reading Helen’s mind, and perhaps Larry’s as well, given that the big astrophysicist’s frame had leaned forward and just as suddenly leaned back.

“Time enough to see the end of the journey tomorrow.”

Rationally, Helen agreed completely with Maddie; there was absolutely no reason to rush, and every reason to be cautious—and despite the startling drop and the casual byplay, Joe
was
being very cautious. And besides, pretty ice formations aside, the end of the tunnel was probably nothing more than that, the end of a tunnel in a lot of ice.

But I still really
want
to see what lies at the end!

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.”