Portal: Chapter Twenty Five

    “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 Ih, but some of those things there look more like octahedrons, which would be Ice Ic, 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!