Both Jeffers and Sergeov still had shadowy slot eyes. Carl said to them, “Don’t bust your butts, guys. Easy does it.”

They checked the mechs’ securing cables and pivoted the array to move up the center of the shaft. Telerobots had towed the microwave-digger assembly, minus its tripod mount, all the way down from the surface. Without its legs it lost its former spidery grace and became merely another lumpy machine, pipes and struts sticking out at odd angles.

Ahead, the smooth surface of the tunnel was broken by purple strands jutting into the vacuum.

—They’re not moving,—Lani said. Beneath her high, melodious voice there was an undercurrent of fatigue.

—How long has the air been gone from this shaft?—Saul asked.

—Days,—Jeffers answered.

—And the temperature is down? Then the purples may be dormant.—

—What’s ’at?—Jeffers asked fuzzily.

Saul glanced at Carl questioningly, as if to ask, Is he groggy?

Carl shook his head. We’re all tired, so what? We haven’t been sitting on our asses in a lab all this time.

—The larger forms apparently were stimulated by leaking heat at the intersections,—Saul sent, —where the collar makes contact with the ice. But once they broke through, looking for more heat, they hit a bonanza. The air warmed them as it rushed out, and the forms kept growing—for a while. Now it’s almost as cold in here as the ice, so they’re dormant again. Mostly.

—Uh-huh.—Jeffers stared straight ahead, somewhat blearily chewing at his lip, and Carl couldn’t be sure the man had understood any of it.

“The purples will break in anywhere the gunk grows,” he said. “That means anyplace there’s heat or light or air.”

They slowed, the mechs’ jets taking up the inertia of the microwave borer. Bulbous Halleyform organisms protruded into the shaft all around Tunnel 3E. In yellow-tinged phosphor light they seemed to be sweating a film of oily blue.

—Beautiful, huh?—Jeffers sent sarcastically.

—In a way,—Lani said somberly, taking him seriously. —So strange…—

“Philosophy later,” Carl said. “We’ve got to kill it.”

—No, I want a sample first.—Saul coasted over to the wall and smacked into it awkwardly. Carl grinned maliciously. Let Saul make his own mistakes. He wasn’t going to waste energy babying anybody, especially Lintz.

—I have not seen them in this state. I had only reports to judge by.—

Oh great. “You mean you don’t know you understand them?”

—Oh, we’ve learned a lot. For instance, we now know that they aren’t really differentiated organisms at all, not like mammals or insects or earthworms. They’re more like jellyfish or slime molds… where different groups of independent cells take on specialized tasks for brief periods. I haven’t seen a phase like this before, but their fundamental chemistry could not change simply because they have a respite in their growth cycle.

The bland professorial arrogance of it irked Carl. “Who says so? How come you’re so sure?”

Saul pulled out a sample bottle. —General biological principles. The resonant frequencies of their long-chain molecules can’t change simply because their life rhythm slows.—

Saul clipped a fragment from the nearest jutting growth and caught it in the bottle. He peered into the open cut, where darkening tissue oozed. —Remarkable. It exudes a film for protection against the loss of vapor to vacuum. Yet the film itself is a fluid that somehow doesn’t sublime.—

“Hey, come on,” Carl called impatiently.

—I suspect it’s a very high-surface-tension fluid Somehow it hinds to the surface, yet remains liquid enough to cover the plant entirely, compensating for injuries.—

Saul clipped a section from another, then pushed off. —Done.—

—Good! Let’s get the microwave oven ready for fried eggplant,—Jeffers said.

Carl directed the mechs to focus the antennas on the plants. There would be side lobes that would lap onto the walls, but that couldn’t be helped. The trick—Saul’s idea—was to tune the microwave borer to the precise vibrational frequency of a molecule peculiar to the native forms so that a short burst would fry them without also heating the ice, nearby.

“Hope you’re sure.”

—The calculation’s straightforward. I’m confident.—Saul eyed Carl. —Look, if it works on purples, I can tune it to some of the worst varieties of green gunk, too.—

“To kill this stuff you might have to blister everything else around. If the exposed ice vaporizes, we’re going to be smack in front of a hurricane.”

Saul caught his look. —My calculations show… oh, to hell with it. Let’s try anyway.—

—She all tuned?—Jeffers asked.

Saul nodded. Carl put his glove on the manual switch “Firing.”

There came a faint buzz beneath his hand as the capacitors discharged, and then the wall flew at him. A white streaming gale hit Carl, blowing him across the shaft, slamming him into the wall.

He bounced off, spun, regained his attitude. The comm line carried grunts, swearing, a yelp of pain. —Watch the spider! It’s gonna crash into the wall,—Jeffers said.

The microwave unit was drifting backward with ponderous menace. If it slammed into the fiberthread—

“Mechs! Mechs!”

Jeffers and Carl leaped for the mech-command module. Stopping the mammoth machine by themselves would be impossible.

Jeffers punched his side console, swearing. Figures moved in the dim light, frantically grappling for purchase on the ponderous, awkward bulk. Mechs surged in several directions, slowing the unit. In a slow-motion swirl they applied force and leverage, while seconds ticked and forces merged.

It worked—barely. The unit bumped into the wall in a slow scraping of green.

“Any injuries?”

—No.—

—Only to my pride,—Saul sent. He brushed at a smear of green on his suit bottom. —Ouch. I guess I must’ve sprained my wrist, too.—

Slowly they assembled. The burst of vapor had blown Lani in a three-bank shot, ending up a hundred meters away.

—Hey!—Sergeov sent. —Regard.—He pointed to the rim of Tunnel E.

“The plants… they’re gone,” Carl said.

—Not just fried. We disintegrated ’em,—Jeffers sent.

—Of that I was certain,—Saul said. —But why so much vapor? Must’ve boiled the water in their tissues. I’ll have to adjust the frequency better.—

“Tune all you want,” Carl said. “Come on! Slap patches on those holes before something else grows through them.”

It took another two hours of tuning before they could blow the native forms apart with a single short burst from the spider and cause only a minor steam-storm of hot steam. Carl slowly admitted that the idea seemed to work. It was hard to get used to.

Dr. Oakes was enthusiastic. She approved orders to bring in two more spiders and crews to man them. If they worked three shifts per day they might clear the most important shafts and tunnels inside forty-eight hours.

The advantage of the microwave technique was that it ripped apart the Halleyforms down at the molecular level—much more effective than chopping them up or tearing them out of the ice by hand, hoping you had gotten every root and strand.

Now, he thought, now to get rid of the goddamn green gunk itself.

Carl began to feel a faint ray of optimism cut through his bone-deep weariness. He sent Virginia slow-frame pictures of purples exploding as the microwaves hit the bulbs. She sent back an enthusiastic “Yaaaaay!” then echoed it artificially so that it sounded in his headphones as though an entire stadium were applauding him. That lifted his spirits more than anything.

They were heading back toward Central, inside a pressurized tunnel, when the madman struck.

“Leave it, leave it, leave it be! You killers! You’re the aliens here!”

They turned to see a man in a tattered ship-suit, hanging from a side passage, glaring at them angrily.