“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.
