The Year's Best Science Fiction--Thirty-Fourth Annual Collection

by Gardner Dozois

  There was a bit of tea-sipping ceremony in the social room, meeting the descent team members, coordinating com links and smiling a lot.

  “You have experience in opening the elephant flaps?” Liang asked, apparently expecting a firm yes.

  Viktor said, “Done in early days, yes. Julia more than me.”

  “Once we learned not to irritate it, no problem,” Julia added softly. Too late, she saw this implied the Chinese had screwed up. But Liang kept his face blank. Better diplomat than I am.

  The roomy habitat’s rear exit fed directly onto the cave entrance, where the anchored robots who assisted descents stood at the hoist apparatus. Somebody in the habitat made the bots all turn and awkwardly bow as the humans approached. Julia laughed with the others. She had not been here since the new Chinese expedition landed and noted that their new cable rig was first class. It worked from a single heavy-duty winch, with a differential gear transferring power from one cable to the other depending on which sent a command to the tending robots. It was the same idea as the rear axle in a car and saved mass.

  Methods had marched on. Sitting warm and snug in the habs, she and Viktor and rotations of crews from China and Europe had robotically tried out dozens of candidate vents. Increasingly, robots did the 3Ds—dull, dirty, dangerous.

  In a decade they found that most fissures, especially toward the poles, were duds. No life within the upper two or three kilometers, though in some there were fossils testifying to ancient Mats’ attempted forays. Natural selection—a polite term for Mars drying out and turning cold—had pruned away these ventures. The planet’s axial tilt had wandered, bringing warmer eras to the polar zones, then wandered away again. Life had adapted in some vents, but mostly it had died. Or withdrawn inward.

  Not this vent, though. It was forty kilometers from the first vent discovered, with a convenient cave entrance, and the Chinese had made it their major exploration target. They got shelter and access.

  The team lowered down twenty meters into it and came to the flat staging area. Unlike the First Expedition, everybody wore white suits—surprisingly spotless, still. Here they picked up the recording and safety gear already delivered by the robots. Bare rock; the robots had cleared away talcum powder–like Mars dust.

  Julia knew she would have to report on this so she got Viktor to stand and deliver an opening line: “Now we go down a deep hole to cross-examine life-form that looks like carpet.”

  She laughed despite herself. “Never pass up a chance, do you, weird husband?”

  He shrugged, a gesture that in their new slimsuits was visible on camera. These days her pressure suit was supple, moving fluidly over her body as she walked and stooped. The First Expedition suits had been the best of their era, but they’d made you as flexible as a barely oiled Tin Man, as dexterous as a bear in mittens. These comfy suits had self-cleaning liners and ’freshers and solved the basic problem—most of the older suits’ weight hung on the shoulders.

  Another descent. She could barely remember the days, decades before, when she had broadcast several times a day, sometimes from this same spot. But back then, they had been breaking new ground nearly every day. And betting pools on Earth gave new odds every time they went out in the rover, for whether they’d come back alive. The good ol’ days.

  “Suit lights off,” Viktor sent on com.

  They advanced toward the first big iris. A double pressure lock, the microbial mat version of the locks humans used to retain air. As their eyes adjusted, all around them a pale ivory radiance seeped through the dark. Julia knew the enzyme, something like Earth’s luciferase, an energy-requiring reaction she had observed in a test tube during molecular bio lab, a few thousand years ago. She recalled as a girl watching in awe “glow worms”—fly larvae, really—hanging in long strands in New Zealand caves, luring insect prey. The Marsmat version was similar, though DNA studies had shown that the Mars subsurface ecosphere had parted company with Earthside evolution over three billion years before. These hardy tapestries of dim gray luminosity, able to survive in near vacuum, were fed from below—from beyond the entrance iris.

  They stopped at the three-meter-wide gray iris, resembling a crusty elephant ear, and stood in silence. Julia and Viktor knew this moment well, this respectful pause experienced in the company of many other crews.

  “It closed up yesterday,” Liang said. “Nothing we do helps open it.”

  “Time to use trick,” Viktor said.

  He reached around to his hip pack and fished out a square box, two wire leads with alligator clips already attached. He fastened one to the outer edge of the iris and another near the center, where the folds overlapped to seal it. He pressed the discharge button at the box’s center. The iris stirred, jerked—and slipped slowly open, driven by the current from the battery.

  Liang said, “You never mentioned this method.”

  “Earthside would accuse us of torturing Mat,” Viktor said. “Committees, reports, lectures—all from people never been here.”

  “So the Mat responds to—”

  “High current,” Julia said. “I got trapped once, Viktor got me free. Turned out I’d done some damage; the Mat answered. Viktor trumped it, though. The Mat uses electrical potentials to muscle its own mass around.”

  “You did not report this method—”

  “Come on through!” Viktor urged, leading the way. Warm wreaths of moist gases wrapped around them, frayed away. The Mat kept itself secured from the near-vacuum above with folded sticky layers. This cave iris was classic, grown at the narrow turn. Viktor held the iris open with more e-jolts as the crew quickly moved through it. Their head beams stabbing into the murky fog as they entered.

  “Think is safe?” Liang asked.

  Julie came through last, eyes darting. She would put very little past the strange intelligence that surrounded them now, as they threaded their way through the bowels of a life-form that was in many ways still beyond their comprehension. The Mat pulsed suddenly, a blue and ivory glow. It knew they were there.

  Again Julia felt the churn of somber, slow luminosities stretching into the foggy darkness beyond their lamps’ ability to penetrate. There was a sense of silent vitality in the ponderous ferment of vapor and light, a language beyond knowing. As a field biologist she had learned to trust her feel for a place. This hollow of gauzy light far beneath a dry world had an essence she tried to grasp, not with human ideas but by opening herself to the experience itself. To Mars, singing through her bones.

  The iris quickly closed behind them as they reached a murky vault that stretched beyond view. Its petals made a tight seal around their cables, decades-old evidence that the Mat learned how to meet challenges. It had done that at the first discovery site, and apparently the knowledge spread—a first sign that the Mat was a global intelligence. Or else had evolved this defense mechanism long ago—against what? Despite decades of wondering which explanation was right, she still did not know.

  Snottites gleamed in their handlamps, dangling in moist lances from the ceiling. She steered well clear of the shiny colonies of single-celled extremophilic bacteria—like small stalactites, but with the consistency of mucus. She waved the team back. “Those mean the Mat is moving a lot of fluid around.”

  Snottites got their name from how they looked, and their energy from digesting the volcanic sulfur in the warm water dripping down from above. Brush one of those highly acidic rods and their battery acid would cut through a suit in moments. A sharp, short ouch, quite fatal. The Chinese nodded, backing away. Good; they’ve learned some of the many dangers here.

  Meters above in the dim pearly glow she saw Mat sheets hanging in a vast cavern. Under their beams this grotto came alive with shimmering luminescence: burnt oranges, dapplings of vermilion, splashes of delicate turquoise. Another silence. Inside the beast.

  All around, a complex seethe of radiance. On Earth, mats of bacteria luminesced when they grew thick enough—quorum sensing, a technical term. A lot of Earthside biolo
gists thought that explained this phenomenon, too. But they had never stood in shadowy vaults like this—the thirteenth such large cavern found in over twenty years of exploration. To see the rich, textured ripples of luminosity that slowly worked across the ceiling and down the walls was to dwell in the presence of mystery. Just ahead, thin sheets of mat hung like drapes. Wisps of mist stirred when they passed by. Unlike scuba gear, their suits did not vent exhaled gases, so they would not poison this colony of oxygen-haters. During the first explorations she had done just that.

  They reached a branching point and elected to go horizontally into the widest opening. Their beams cast moving shadows, deepening the sense of mystery. Within minutes they found orange spires, moist and slick. Beyond were corkscrew formations of pale white that stuck out into the upwelling gases and captured the richness. More pale, thin membranes, flapping like slow-motion flags. The bigger ones were hinged to spread before the billowing vapor gale. Traceries of vapor showed the flow direction, probably still driven by their opening the iris diaphragm. One spindly, fleshy growth looked like the fingers of a drowned corpse, drifting lazily in the current. It reminded her that so far, thirteen people had died exploring the Mat, all around the planet. There would be more deaths. She always reminded new crews that Mars was constantly trying to kill them.

  But something was wrong. She had been here when the Chinese first arrived, waiting for their major gear to set up the plumy habitat they now used—and the Mat then was vibrant, alive. Now big swaths of it were dull, gray.

  “Was it like this last time you were here?” she asked.

  “Yes, we were studying the change when the iris lock began closing. We barely escaped.”

  Julia studied the postures of the Chinese team. Did they look embarrassed? “Smart. It can respond quickly. Earthside says the samples we sent back in 2025 imply the Mat was here about 3.5 billion years ago, and we share DNA—so it’s been evolving as a single entity since then. It can be quick, but prefers slow. I think it sees us as mayflies.”

  They looked puzzled. Liang kept his face blank.

  “Look—here, pressure is precious. The Mat evolved to seal off passages, build up local vapor density. Then it could hoard the water and gases it got from below. But it has to seal breaches fast. It’s killed people before; be careful.”

  The closest comparison Julia and other biologists had been able to make was to Earthly stomates, the plant cells that guard openings in leaves. The iris opened or closed the holes by pumping fluid into the stomate cells, changing their shape. But analogies were tricky because the Marsmat was neither a plant nor an animal—both Earthly categories—but rather another form of evolved life entirely, another kingdom altogether. Some thought it should be classed with the Earthly biofilms, because some Marsmat DNA closely matched—but the Mat was hugely more advanced.

  Yes, the Chinese were both embarrassed and puzzled, judging by their faces. “Get samples of damage,” Viktor told them. That unfroze them and they spread out, taking small snips.

  Liang eyed the entire chamber. “The damage looks worse. It is spreading.”

  “Glad we could help,” Julia said, though not really glad at all. She knew this sickly gray plague was different. Her alarm bells were ringing. “Let’s stop pestering it—out!”

  MICROBIAL WISDOM

  Julia studied their distant Marsmat sites by reviewing past observations, looking for any signs of the gray swaths they had seen. Every time she looked, the intricate Byzantium of the Mars underworld captivated her.

  Earthside subterranean life—microbes, mostly—ran many kilometers deep. In total mass it just about equaled the oxygen-loving life above. Underground Mars life had natural advantages over Earthside. Lower gravity meant that cracks and caverns could be larger. The early plate tectonics of Mars had shut down, so the whole planet froze up. Olympus Mons was the largest volcano in the solar system because the lava that built it came up the same chimney, and nothing moved, ever—so the chimney erected a vast shield mountain. On Earth, the same sort of persistent eruption built the Hawaiian island chain, where tectonics kept steadily moving the upper surface, dotting the ocean with new volcanic piles that made the islands.

  The static Martian crust meant that, once formed, caves and cracks were never closed up again by the ceaseless movement of rock layers, as they were on Earth. Mars was also cooler, right down to its core. So milder temperatures prevailed farther beneath the surface, and the working volume of rock available for life to thrive in was bigger than the inhabitable surface area of Earth. Even the pores were larger, due to the lesser gravity and rock pressure. Plenty of room to try out fresh patterns, she thought. Over four billion years. Over the whole planet. All one big … mind?

  They still didn’t know how all-embracing was the network of habitable zones available to the Marsmat. Seismic data alone could not tell them what all those open volumes held. To learn that they had to make laborious descents, their reach prolonged by oxygen bottles and supplies stashed earlier—hard, grueling work. Living in a suit for days was not just tiring—it ground down the spirit. The gloom of those chambers, the pervasive atmosphere of strangeness, the creeping claustrophobia—all took their toll through the years. Everywhere they had gone, there was the Marsmat, linked by intricate chemical cues, vapors, fluids.

  Julia sat in their very own, original First Expedition habitat—upscaled a lot, but homey—and pondered the 3D cavern maps of the entire nearby area—a Byzantine spaghetti of life zones.

  Viktor said from his work desk, “Time for dinner.”

  She said, “In a minute. Vulet over in the main hab is looking through all our old videos for me.”

  “For great discoverer, da.” Julia’s Earthside fame was a running joke between them now for two decades. “Vulet says—here, quote: ‘The Mat’s reaction to repeated violations of its integrity by humans—oxygen exposure from leaks and exhalations from their early suits—never presented the gray swaths seen now in China Cave.’ So it’s new.”

  “Chinese at fault?”

  “I don’t want to provoke them.”

  “Must poke to know.”

  * * *

  Amazing, Julia thought, how large a month of the hab’s shit was!

  The next morning she had showed up for her Task Assignment. The Mars Code: everybody works. No exceptions. Especially for Earthers fresh in—no tourism!

  As she passed through the main hab mess hall, some of the new Earthside socko music was playing and people were dancing to it. To her it sounded like a rover flange coupling had gotten loose, flapping against the hull, and so the hell with it.

  Mars Operations minimized manual labor, but robots couldn’t handle everything. Like this. First their team pulled the plastic bag from the hab underskirting and onto the hauling deck of a truck that growled like a caged animal, which in a way it was. It doubled as a mobile power source, 100 kilowatts electrical, able to crawl anywhere on hard, carbon fiber treads. She boarded the hauler and checked the long-term weather while she waited for interior systems to self-check: a category 4 storm was coming, with winds gusting to 80 km/hr.

  She noted that the air lock seal was hissing, so either it had snakes in it or needed a smart patch. She told her helmet to send an alert to Main Hab. To Earthside, equipment failure was alarming; for Julia, it was just “Thursday.” Holes? Duct tape. Electro: re-rig it in the shop. Computer? Pull a board, usually, and let the smart 3D printer figure out what needed doing. Mars liked improvisation.

  While she worked, the team lugged the goodie bag of brown across the landscape—a big, rich gift to Mars inside a mercifully opaque plastic sack, compacted and frozen solid. The Planetary Protocols demanded that human waste be taken several kilometers from habitats, then buried in perchlorate-rich sands. But not too deep—the site had to be water-poor, unable to let waste trickle down into the volumes where the Mat lived.

  Ecology wasn’t just some science here, it was life itself. The hab used toilets that neatly separated s
olid and liquid waste—nature gave them separate exits, after all—and the urine got recycled, since it held 80% of the useful nutrients in their wastes. Kitchen scraps, of course, went back into the greenhouses. In the early days building the greenhouse, they had used “humdung,” the Earthside euphemism, for building the topsoil. Soon enough Earthside had reduced the term to TOTS, Take Out the Shit, an acronym that quickly became a hip shorthand Earthside for doing drudge work.

  The one trick the bioengineers had not yet managed was converting most of the solid wastes to anything useful or even non–sickening. Let somebody else “realize existing in situ resources,” as the manuals had put it, by composting. Frozen, it would keep.

  Yesterday’s ground crew had already dug the pit for it, a few klicks away across rocky terrain, using a Rover Boy backhoe. The perchlorate dust was the bizarre surface chemistry’s sole advantage—it plus the constant UV made the risk of contaminating the biosphere below tiny. Perchlorates ate up fragile biological cells in seconds. This surface was the most virulent clean room in the solar system, down to five meters. Any mess that escaped, Mars would kill every single cell within an hour.

  As she worked she thought. The Chinese kept their methods secret—that had been only the second time she had been invited into their main hab. So she knew nothing about how thorough they were. Humans were walking litterbugs. They shed human dander, duly vacuumed up and used in the greenhouse for valuable proteins and microrganisms. Early on, she had set out a sample—“a dish of dander,” she had called it in a published Letter to Nature—and Mars had killed every single cell. That kept the Marsmat isolated from both the searing surface and the alien, invading humans.