The Martian Race (42 page)

She glanced over at Marc as they played out line. Something in his face told her that he was having the same thoughts. Had reached the same conclusion. And neither of them had needed to talk about it.

They got the oxy tanks past the Y-frame that routed the lines. It was awkward getting the bottles set right. Then the two of them backed over the lip and negotiated the bottles into place above them.

In their suit lamps she could see him concentrating on where his feet were, how his weight was displaced—the riveting attention trained into them by the years. After all the gut-churning tension of the last few days, it actually felt good to be
doing
something—clean, direct, muscles and mind.

They went down gingerly, parallel to the Airbus monofilament cables. Marc said, “I wonder if that differential was built after seeing our plans?”

She grimaced, puffing as the winch lowered them both into an inky well. “Why not? All's fair in a race.”

“Look there,” he called.

From below seeped a soft ivory glow. The darkness above them made the seeing different this time. A thin mist boiled up and cloaked the radiance in streamers of gossamer finery.

“Careful not to touch the mat,” she said.

“Marshroom, you mean.”

“I certainly do not.”

They moved down fast and the glow ripened. The Airbus cable plunged straight into inky nothing.

They passed by the increasingly lush mat. Some phosphoresced in pale blue and ivory. Others seemed to have earlike fans to catch moisture. She had memorized parts of this, the pieces she had caught on video.

“It all seems different,” Marc said. On comm she could hear him breathing steadily and deeply. Heavy work at the end of the day, not recommended …

“No sunlight. The mats do seem brighter.”

“Maybe something's stirred them up.”

“It's misting pretty heavily.”

“I was thinking maybe Chen and Gerda.”

Down, as fast as the winches could go.

In the torch beam they found the ledge where they had gone to the left.

“That way led into the large horizontal cavern,” Marc said.

The Airbus cables went to the right. “It looks steeper their way,” she said. The Airbus lines sagged into the turn, not taut, not bearing any weight. “Wonder what that means?”

“The mist is getting heavier,” Marc said.

“There's a wind.” She watched coils of speckled moisture rise past them.

“Hope this vent isn't getting set to do something big.”

“Unless the mat is giving off some vapor.”

“Why would it?”

“Transport of water from the interior. The top is always drying out, getting cold.”

“You mean the system has circulation?”

“Outflow, yes. I wonder if the mat somehow regulates it.”

“Could it?”

“Earth's whole atmosphere and climate is regulated by plants and animals.”

“Sure …” He looked at the luminous mat gliding past as the winches carried them down. They were far enough out to keep the oxy tanks from smacking into the sides, but she knew some damage was inevitable.

No
chance for pristine intrusion. I'll catch hell for this with the Earthside biologists.

At the edge of her vision she sensed something and stopped her winch. “Look, some mat is dead.”

“Yeah. I don't remember doing anything like that when we came through here.”

“Me either. Turn off your lamps.”

They plunged into blackness.

The glow gradually built up in their eyes. “Right, there's a lesion on the closest mat,” said Marc.

She swung gently over, peered at it. The oxy tanks above were handy for this, providing a local pivot. “Probably they stopped here and their exhales did this.”

“Pretty big patch.”

“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.”