“If I'd told him about my descent he could have avoided doing this.”
“Hey, don't blame yourself. He was calling the shots, remember, making deals.”
“Well, at least we'll get a look at some new territory.”
They turned their lamps back on and let the winch take them down. She pulled out her microcam and began shooting the mat as they went. The mats were growing ever larger and thicker as they went lower. They covered most of the tube walls now, stacking thickly on every available out-jut, then working up the verticals.
“How far along are we?”
Marc looked at his digital readout from the winch control above. “Three hundred point four meters.”
“Let's pick up the pace. If—what's that?”
“Another lesion.” Marc swung over to look: “They must've—”
“Look! It's the same shape as the damage above.”
The mat around the wound glowed brightly with pale phosphorescence.
“They made the same pattern each place?” Marc asked. “Some kind of experiment Chen was trying?”
“Beats me.” It seemed to be changing as she watched. “Look at it out of the corner of your eye,” she said. “See?”
“It's spreading downward.”
She leaned over and peered around. “The glow increases below.” They looked down the vent.
Marc said, “It's definitely brighter down there.”
“Let's go.” They descended carefully, playing out line. Their lamps washed the mats in glare that seemed harsh now. Twenty meters down she said, “Lamps off again,” as they rested on a shelf.
When her dark vision came back her eyes were drawn to a splotch of light. “Damn! How—?”
“It's the same shape again.”
“Right.”
Marc asked, “What the hell?”
“A mimicking image.”
“Naw, can't be …”
“Parrots imitate sounds, this mat imitates patterns imposed on it, even destructive ones. But why?”
He drawled, “I'd say the question is, how the hell?”
“The mat here learned about the wound above.”
In the blackness Marc's voice was baffled. “Learned?”
“Echoed, at least. Maybe automatically.”
“Okay, they're connected. But why the same shape?”
She wondered herself, and guessed, “It's a biological pictograph. I have no idea why. But I am sure that any capability has to have some adaptive function.”
“You mean it has to help these mats survive.”
“Right.”
On with the lamps and they dropped again. This tube was very nearly vertical, which made their descent quick. Still, time was narrowing. Julia felt incredulous, wondered if she was imagining the similarity in the damage patterns. But no: the image repeated on successively lower mats twice more, five meters apart.
Off with the lamps again. She gazed back up. The blurred gleaming above had faded. So it was not just a simple copying, for some pointless end. “The pattern, it's following us down.”
Alarm filled Marc's voice. “Tracking us?”
“See for yourself, up there—the image is nearly gone, and the one next to us is brightening.”
“Are you implying it knows we're here?”
“It seems to sense what level we're on, at least.”
“The one here is stronger than the others.”
“I think so too. Brighter the deeper we go. The glow is purely chemical, some signaling response I would guess. Maybe the denser vapor here deep in the vent helps it develop.”
“Signaling?” Marc sounded worried.
“Maybe just mimicking. Light would be the only way to communicate downward here. It couldn't use chemical means to signal downward, the updrafts of vapor would blow them away. Sound could go either up or down, but it doesn't carry well in this thin an atmosphere.”
His voice was strained in the blackness. “There's got to be a simple explanation.”
“There is, but it doesn't imply a simple organism.”
“Maybe it's … signaling something else …”
“And if it's brighter the deeper we get, maybe that means … something below?”
“The Airbus cable, it's still slack.” He kicked it and waves propagated both up and down. At the next ledge down the lesion image began to swell into a strong, clearer version.
Something beyond comprehension was happening here and she could only struggle with clumsy speculations as she worked. Somehow the mat could send signals within itself. There were many diaphanous flags and rock-hugging forms, getting thicker, most of them pasty-colored. Somehow they all fit together, a community. They used the warmth and watery wealth here and could send signals over great distances, tens of meters, far larger than any single mat.
Why? To sense the coming pulse of vapor and make ready? A clear survival value in that, she supposed. Could organisms evolve such detailed response in this harsh place? Could a biofilm do it? On Earth they were considered to be early, primitive forms with severe limitations. Or had biofilms just been outrun by other forms in the rich, warm, wet oceans?
With their lamps off she took video shots of the ghostly lesion images with her microcam, though she was pretty sure the level of illumination was too low to turn out. She would memorize all this and write it down in the rover. Careful notes …
“Their lines just keep going,” Marc said, looking down as they descended.
“I'm nearly halfway through my oxygen.”
“So would they have been, when they got this far.”
“This goes nearly straight down. Not like the way we went.”
“There's been no plate tectonics for a long time, remember. Nothing to shear a volcanic passage like this, twist it around. So lava just came pretty much straight out. This tube, it's probably a couple billion years old.” Marc seemed a bit spooked by the mat, but more confident with geology.
“Getting narrower though.”
“This mat is getting thicker, too.”
Her lamp was on high, poking down, so she saw it first. “What's that?”
Far below was an oatmeal-colored floor. They stopped just above where the two Airbus cables forked straight through the middle.
“Where'd they go?”
“They got through this thing,” she said.
It looked like two massive, cupped palms pressed together at the center. The whole structure was perhaps three meters across. Maybe not an accident that it's here, where the vent narrows down.
“Some kind of valve?” she speculated.
“Looks pretty solid.”
“Reminds me of stomates,” she said. “Plant cells that guard openings in leaves. The plant opens or closes the holes by pumping fluid into the stomate cells, changing their shape.”
“The mat is a plant?”
“No, it's something we have no category for. A film, a biofilm—but one incredibly more advanced than the simple ones that grew in the early oceans of Earth. These have had billions of years to follow a different path.”
“Well, it's sure good at blocking our path.”
“But it didn't stop Chen and Gerda.”
“Maybe it was open when they came through?”
“That's it. This structure seals the tube, maybe to protect the lower vent—”
“From what?”
“Peroxide dust? Maybe they irritated it, so it closed up.”
“So if we poke at it…”
“Good idea.”
She lowered directly onto the thing, boots sinking in. “It can hold my weight. Wow, that's strong.”
“For a plant, yeah.”
She walked around on it. “Some give to it, but—wait, I have an idea.” She winched down so she could sit down. “Ugh, not easy in these suits.”
“What's up?”
“Maybe my air exhaust will tickle it.”
Abruptly it flexed. She automatically reached for her winch control, but the membrane gave
way faster. It retracted and she lost her footing. A hole opened at the middle and she skidded through. The surface was slick now and she stopped halfway through the opening.
“Hey!” Marc called.
She stabbed at her winch control and played out the line, slipping fully through. As she looked up the opening widened. She was dangling just below the roof of—
“My God, it's huge,” she said.
Below and around her was a murky vault that stretched beyond view. As her lamp swept around the fog reflected back its glare. But to the side she could make out a sweep of radiance that dwindled into the distance—the ceiling of a vast cavern.
“You okay?” Marc peered down at her through the opening.
“Fine. Come on through.”
“What if it closes up on us?”
“We'll kick our way back out.”
“What if we can't?”
“Look, the Airbus cables just keep going straight down, so they didn't get trapped by this … this valve. Let's find them.”
“Valve?” Marc asked as he lowered himself through.
“Maybe that's what it does. I dunno. Theory later. Look.”
With lamps quenched, the gloomy grotto came alive with shimmering luminescence: burst golds, dapplings of orange, vermilion splashes that laced through turquoise filigree.
“My God, how big is this?” Marc whispered.
“Can't see the walls.”
“Or the floor, through this vapor.”
“So bright, the walls— Turn off your beam.”
Without the back-scatter from the fog she could make out dim glows tapering away on all sides. Like the signature of a distant city …
“It's moving. See, on the ceiling.” He gestured up.
She played out line to watch the shifting pale patterns above them. Hanging in the blackness, she could see, achingly slowly, the complex seethe of radiance.
She was too stunned to think. Okay, so act. “Well, nowhere to go but down.”
“Yeah … What's doing this?”
Damnned if I know. On Earth, mats of bacteria luminesce when the bacteria get thick enough. Quorum sensing, it's called. Here, who knows what could have evolved—colors? shapes? patterns?
“Come on.” She winched down, leaning back in the yoke to watch how her line fed through the hole in the membrane. The cable did not rub against the edges of the thing. It had opened further, maybe two meters.
Marc followed her. “Could all this be directed by intelligence?”
“Doesn't have to be. Sentience is not the same as intelligence. There'd be a huge selective pressure in favor of controlling the loss of gases. Maybe that's what the valve does.”
“This is some kind of instinct, then?”
“Can't tell from what we've seen so far.” She turned and gazed down. The flush of light from below was getting well defined. More of the curious swirls and blotchy colors, as above. How close to the floor were they? She let herself down a few more meters and called, “I'm going to turn on a beam. Close your eyes, so one of us keeps night vision.”
“Roger.”
When the beam stabbed down she took her hand off the winch command instantly. About five meters below them were two space suits, one orange, one blue. Facedown. They did not move.
36
FEBRUARY 1, 2018
THEY DANGLED OVER THE TWO FACEDOWN SUITS AND MARC CAREFULLY lowered himself to within a foot of the orange one.
“Gerda,” he called on comm. Nothing. “Chen?”
They looked at each other, only a few feet apart. “Turn her over. Be careful—it looks like the mat has partly grown over them.”
“This fast?”
“Don't think of it like a plant.”
“I wonder if I can turn her over from here.”
“Try. Don't put your weight on the mat.”
Marc pivoted in his yoke and took hold of Gerda's suit with both gloves. “Man, this stuff pulls hard.” His angle was bad, and finally he had to lift Gerda. The pale mat growths resisted, stretching until they popped free. In normal Earth gravity lifting that much would have been impossible, but with some grunting he managed to get her turned over. Her eyes were closed. No expression.
“I can make out her internals,” Marc said, shining his beam through her faceplate. “Air's to zero.”
“See those tanks lying to the left?” She craned her neck. “Reading full.”
“So they're … dead.”
“No way to be sure unless we crack their helmets.”
“They're way beyond the time limits on their tanks.”
“Explains why they didn't answer. Their audio connection shorted out along with the winch, I'll bet.”
Marc turned over Chen with the same difficulty and same result. Chen looked peaceful, somehow. “This damned mat, it's all over them.”
“Maybe they got snagged in it somehow. Looks like ropes of blue linguine.”
“For some reason they couldn't hook onto their oxy.”
Marc gestured at the small distance between the bodies and the tanks. “They were close enough. I can't see how the mat could stop them.”
“I have no idea what it can do.” She suddenly remembered the pale blue filaments in the mist chamber. “Marc, I saw some of these same shapes and colors in the Mat growing in the greenhouse. Only much smaller.”
“It's just a plant,” he insisted.
“It may be a lot stronger than it looks. That valve thing up there, it was pretty—”
“I'm not touching it, tell you that.”
“But they did … They must've detached their tanks from their line. Dropped them onto the mat. It would be hard to put them on, dangling here.”
“So they landed and tried to get their oxy—wait, what's that?”
Their beams found scattered instruments—cutters, sample bags, a big box. She said, “Chen was taking samples. Look at those filaments to the right—they're sliced. He was partway through with the job, looks like.”
“Did it before they changed tanks. Not smart.”
“They're new, not much real experience.”
“See that?” Marc swung toward the spot. “Looks like an oxygen burn, right by Chen.”
“He was testing it, maybe. Look, there are other burns over there. Deliberately spraying it with his exhale exhaust?”
“I still don't see what killed them. This film thing, how could it—”
They both looked up. A tremor had come down their lines.
“Oh damn,” Marc said. He started winching up at max speed, training his beam upward.
Julia thought she knew what was coming but turned back to Chen and Gerda. For a moment she was alone with them. Why try to do it all? If you had just asked we would have warned you, shown our videos—
No point in going there, not now.
“That goddamn valve thing,” Marc called. “It's closed around the lines.”
“We've got to get out.”
“Right.” She could hear his breathing quicken. “Only we're down to around ten percent left on our tanks. I don't wanna get into the jam they did.”
“I agree,” she said, looking away from the bodies and trying to think. “Let's do the switch right now.”
“Agree.” He came winching down.
The change of tanks proved to be even harder than she had feared. On their last descent they had done the switch standing on a ledge. In air, even with lower gravity, it was a struggle to detach their nearly finished tanks and get the new ones in the sockets. They kept the old tanks secured to their lines. Each helped the other but it took over ten minutes.
“Whoosh, glad to get a full one,” Marc said.
“We had better think through what we do. It looks to me that Gerda and Chen didn't.”
“Okay, what'll we try? Me, I say we hammer at that valve up there. Leave these bodies.”
“I hate to leave them in the mat. Not just humanitarian reasons— don't want to contaminate this community.”
�
��Community?”
“This mat is a complex structure. Rootlike filaments, thick petals, moss, lichen … those are just analogies. Maybe it's like a higher plant in level of complexity and organization, even though it's a mixed community of microbes.”
“Ummm. I wonder if there's another way out of this place?”
“Another vent? Could be—but do we have time to look?”
“No,” he said decisively, “not with just a few hours left.”
They hung just above the mat and watched the slow, strange ebb and flow of phosphorescence. A chill came into her, not from temperature, but a shiver that ran along her spine with icy fingers as she felt the hair at the nape of her neck stand up. Something more here … something different … She looked to both sides, at the chum of somber luminosity that stretched away into the foggy darkness beyond their lamps’ ability to penetrate. There was a sense of presence, a weight in the slow, ponderous seethe of vapor and light, like a language beyond knowing. As a field biologist she had learned to trust her feel for a place, and this hollow of light far beneath a dry world had an essence she tried to grasp, not with human ideas, but with a blunt, root perception …
She was looking behind him and so saw the movement first. “It's rising.”
“What?”
By the time Marc had spun around the bulge in the mat was a foot high. A spaghetti swarm of pale blue strands was lacing through the dark mat, stretching and expanding like tendons in some strange muscle that rose just fast enough to see the change. It was a few meters away and tilted toward them as it sluggishly rose. Tubular stalks slid among cakes of brown crust. Fibers forked into layers of dark yellow mass and seemed to force up slabs of porous mat. An outline shaped itself and the whole structure seemed to bud up, as if a wholly new plant were emerging from the moist conglomerate surface.
Julia's heart thumped wildly. She held herself absolutely still in her harness and watched, timing the movement of the thing with her own breaths. In utter silence the mass forced itself up and toward them. She felt a palpable sense of something struggling, putting vast concentration into this one focal point.
“My God,” Marc said. “It's …”
A chunky rectangular form, the top turned toward them. Two branches sprouting at the top, shaped by the blue strands. She blinked. At its base, two more protrusions, slabs of dark mat forming with aching effort into thicker tubes … And from the upper sides, above the two thickening tubes that now jutted from each side … a third blob, of ebony as thick as tree bark, pulling itself out from the main trunk.
The Martian Race Page 33
