From a distance, Newport’s World looked like a typical outer-belt snowball, a poor prospect for uranium. But the asteroid smelled like uranium to the Buck-Dancer’s Choice particle detector. After the last washout, Blue Heron was not going to argue. All they had found on that rock was radium and a scattering of low-grade uranium sulfate. They would have lost money trying to refine the ore. Heron had picked that rock out himself, so there was no blaming it on anyone else. At least Captain Cole would take the heat if this prospect did not pan out.

“What do you make of it, Blue?” Cole asked.

Heron shook his head, flipping through different sensor channels. “It’s massy for a snowball, and I’m picking up some alpha particles. The flux varies; it could be an exposed node of uranium.”

“Can you get a fix on it?”

Heron dropped out of real time and integrated his readings into a three-dimensional model of the asteroid. He studied the puzzling image for a few moments before replying. “There’s more variance than can be accounted for by the rock’s rotation.”

“In other words,” Cole said, “no.”

Heron shrugged. He could not change his instrument readings. “Maybe someone has already established a base. These traces look a lot like an active mining operation.”

“Listen to the expert,” Cole said. “I checked the records. Newport got run out years ago and it’s been deserted ever since.”

Heron shut up. He was tired of the sarcasm, but he was just going to have to ride it out. Either he would prove his worth to the Buck-Dancer’s crew, or he would find a berth on another mining ship.

“All right,” Cole said to the bridge crew. “Let’s haul up and anchor down at one of the poles. We’ll see if we can eyeball the ore in person, since our remote sensing specialist can’t spot it for us.”

Across the clustered consoles, the ship’s engineer caught Heron’s eye and shrugged. Greg had been on the Buck-Dancer’s Choice since the ship was commissioned and was seldom the target of Cole’s scorn.

Cole switched on the intercom. “All hands secure for high acceleration. Report your status.”

The Buck-Dancer’s crew of sixteen sounded off as they made ready. It did not take long to account for everyone.

“Stand by for acceleration,” Cole said over the intercom.

A rumbling vibration came from the stern as the fuel pumps turned over. The propellant passed through the motor’s electric arc with a bang and Heron was pushed back into his seat as the ship began to accelerate. A flicker of motion on the rock caught his eye, but the weight of acceleration slowed him down. By the time he had zoomed in on the spot, it had rotated out of sight over the horizon.

#

One long burn killed their relative velocity and left the Buck-Dancer’s Choice hanging a few kilometers above the asteroid’s heavily-cratered north pole. The less time the motor was lit, the less likely that someone would observe them and come to visit later. Mining was a hard business, full of abandoned camps and plundered claims.

“Looks like we’re not the first ones to check this place out,” Heron said. The wreckage of another ship was strewn across the crater floor. “You want to stay here, Captain?”

“Is the wreck radioactive?”

“Slightly,” Heron said. “Not enough to be the source of what I was picking up, though.”

“What do you think, Linda?” Cole asked the ship’s medic. “The radiation will help conceal our reactor emissions if anyone scans the area.”

Linda glanced over the readouts. “Our shielding can handle these levels. Anyone who goes outside will have to wear a shell.”

Cole nodded. “I can live with that. Go ahead and fire an anchor, Blue.”

Heron aimed the Buck-Dancer’s coil gun at a clear area near the wreck and squeezed the trigger. A puff of dust marked the hit. Seismic data flowed back up the anchor line and his model of the asteroid began to fill with a blurry representation of its internal structure.

A deep regolith of pulverized rock covered the asteroid and gave it a radar signature similar to that of a snowball. Underneath the dust was a hard rock core. Shadowy lines within the core could have been fracture planes from asteroid impacts or the signature of extensive underground facilities.

He put the analysis on the net so the others could see it. “Just what was this Newport character doing out here, anyway?”

“Some kind of robotics research,” Cole replied. “The footing looks good; take us in.”

Heron shrugged and turned on the anchor line winch. The ship jerked as the line came taut. Then they began to settle slowly towards the surface, aided only slightly by the asteroid’s weak gravity.

“Greg,” Cole said, “I want you and Heron to explore that wreck after we touch down. We might get some useful salvage out of it.”

#

Heron’s shadow was crisp on the asteroid’s chalky regolith. He scooped up a handful of the dust. It consisted of finely pulverized silicates. He let the dust trickle through the stainless steel fingers of his shell’s manipulator and then straightened up. The floor of the crater was pockmarked with a rough grid of conical pits.

“You think the ship crashed here?” he asked Greg. If the ship had broken up before it hit the asteroid, it might explain the pits.

The engineer shook his head. He looked like a lobster in his shell, soft meat inside ceramic armor. “No, its basic structure is pretty much intact. It was stripped after it set down.”

“Claim jumpers,” Heron said.

“Could be. What do you make of these pits?”

“They’re hotter than average,” Heron said, “but I can’t figure out why.”

“Of course not,” Cole muttered over the radio. There was muted laughter in the background. Heron recognized Linda’s voice and felt himself blushing. The bastards never let up.

Greg ignored the comment. He slid a set of digging tines down his shell’s forearm and locked them into place. “Let’s have a look underneath.”

The engineer’s digging tines scooped deeply into the regolith. He levered the blades out of the dust. Attitude thrusters on his shell’s shoulders flared to counteract the torque and keep his feet on the surface. The arc-jet thrusters produced a hiss of static that was clearly audible on the radio.

Something that looked like a mechanical sperm was caught between two of the tines. A root-like tail writhed slowly below an angular head. Greg brought it closer to his face so that he could see it better. The tail cracked like a whip and hit his shell just below its faceplate. There was a searing flash of light as the shell’s radiation shielding discharged.

“Shit!” Greg shook the thing out of his tines. It started burrowing back into the dust.

A burst from Heron’s crest laser cut the thing’s head in two. The tail spasmed once before it seized up. Heron’s faceplate superimposed a bright glow of alpha particles over the robot’s interior. He rolled the larger half over with his foot, careful to stay clear of the tail. It looked like a nuclear battery inside.

“How’s your suit?” Heron asked.

“Shielding is coming back up,” Greg replied after a moment, “but I’ve lost a couple rings where the ceramic chipped. Pressure’s holding steady.”

Pressure wasn’t as critical as shielding. Both men were wearing skinsuits inside their shells. If a shell lost pressure, the skinsuit automatically sealed to protect its occupant, but a skinsuit did not offer any protection from radiation.

“It could be some kind of mining robot,” Cole mused. “The tail could extract uranium from the regolith and concentrate it in the head.”

“We’ll take a look in the wreck,” Greg said. “There may be more of them inside.”

“I don’t want you both going inside,” Cole said. “The hull will cut our radio link, and if you didn’t come back out we wouldn’t know what the hell happened. Heron, your shielding’s tight. You check the ship, and lay an optic back to Greg so he can relay your telemetry to us.”

#

The wreck had gone down on her side. She had roughly the same layout as the Buck-Dancer’s Choice, a hundred-meter cylinder with the main engines at one end and the glassed-in bridge at the other. Cargo pods and fuel tanks ringed the cylinder’s midsection above the twisted landing gear.

A hole the size of a small truck had been ripped in the wreck’s side; titanium plate had been peeled back like foil. Heron pulled himself through the opening. Fiber optic spooled smoothly off a reel mounted on his shell. The thin line spiraled back to Greg, waiting on the ground beside the ravaged hull.

“How’s the picture?” Heron asked.

“Clean on my end,” Greg said. “Captain?”

“We’re recording,” Cole said.

A broad corridor of destruction led towards the stern of the ship. Whatever had ripped through the ship had not bothered with the niceties of bulkheads and hatches.

“It looks like someone drove a bulldozer through her,” Heron muttered.

“She was a miner, all right,” Greg said. “Check that spectrometer on the wall above you. We’re in her lab.”

Heron moved slowly through the wreck, panning his shell’s camera over the carnage for the sake of the Buck-Dancer’s crew. There wasn’t much left worth salvaging; with the exception of a few instruments like the spectrometer, most of the ship’s gear had been stripped out. All that was left was a tangled mess of wiring and ducts.

“Hold it,” Cole said. “What was that over to your right?”

Heron turned to look, then focused his headlights on a combat shell wedged between a locker and a desk. A hole had been melted in its back, exposing the core of its fission reactor.

“It looks like most of the core is gone,” Heron said, puzzled. The room should have been flooded with radioactivity, but the emissions from the shell were minimal.

Heron squatted down and heaved the shell over. Its faceplate was hazed with frozen air and blood crystals; he couldn’t see the suit’s occupant. He pulled the shell’s emergency release and the top hatch popped up a centimeter.

“The frame’s twisted,” he muttered. He jammed steel fingers under the edge of the hatch and levered it up the rest of the way, bending the rim in the process.

“Sweet Jesus,” Linda said softly.

Heron clenched his teeth to keep his bile down. The shell’s occupant had been baked alive. His tongue had swollen out of his mouth from the heat, and the lenses of his eyes had congealed and burst from their gelatinous sacks like milky-white marbles.

“It would take a couple minutes to burn through a shell with a standard crest laser,” Greg observed analytically.

“What kind of person could do that to another human being?” Linda wondered aloud.

“All right Blue,” Cole said. “Let’s move on. The salvage team will haul out the body.”

Heron swallowed and backed away from the corpse. He could feel his heart beat against the claustrophobic constraint of his shell. He nervously checked the status of his laser before moving on.

The trail of destruction stopped at the wreck’s engine room. Heron’s faceplate painted a residual glow of radioactivity over broken fittings and severed mains.

“The reactor’s gone,” he said.

“I guess you were right, Blue,” Greg’s voice came over the fiber optic. “Someone came and jumped them. Took their ore and their reactor and ran.”

“Yeah,” Heron said, thinking about the shadowy lines under the surface of the asteroid. “I suppose so.”

#

Back inside the Buck-Dancer’s cafeteria, Greg and Heron huddled over bulbs of burnt coffee. They had not bothered to take off their skinsuits; the work day was just beginning, and they would be going out again soon enough.

A salvage team suited up in the adjacent ready room. Ceramic plating scraped and clanked as the miners wormed into their shells and tested motor circuits. Cole watched critically from the doorway, arms folded across his chest.

“We’re ready to go,” the team’s foreman said over the intercom. In her shell, Harriet towered almost a meter over the captain.

“Listen up,” Cole said. The clanking ceased. “I want you to be careful over there. Buddy up and stay in contact with each other. Bug out at the first sign of trouble. I don’t want to lose anyone.”

Behind their faceplates, the miners nodded soberly.

“All right. As of now, you’re on hazard pay. Take your time and do a good job.”

There were a few grins at that; hazard pay was set at double-time. Cole sealed the door and joined Heron and Greg at the scarred plastic table.

“You bet I’ll take my time at that rate,” one of the miners said, forgetting that their radios were keyed to the intercom circuit.

Someone else chuckled. “Damn straight.”

“Decompression in five seconds,” Harriet said, cutting off the rising chatter. “Speak now or rest in peace.”

Heron shifted his chair so he could see the monitor mounted on the cafeteria’s bulkhead. It held a fish-eye view of the miners as they trouped through the Buck-Dancer’s mobile equipment bay, past rows of parked ore handlers and exploration vehicles. Frequent pressure cycling would have created a maintenance nightmare, so the bay was usually left open to vacuum.

“Are you going to need more seismic data before we can start hauling rock?” Cole asked. Heron turned away from the monitor, caught off-guard.

“The map we got off the anchor shot was pretty blurry,” Cole continued.

“Yeah,” Heron said, thinking about the anomalous signature, “blurry.” He cleared his throat. “A blast at the south pole should do it.”

Cole shifted his gaze to Greg. “Go ahead and take the drill truck. And keep Blue from hurting himself, all right?”

Greg nodded impassively and pushed himself away from the table. “If we’re not back in a couple hours, send out the cavalry.”

Heron followed Greg into the ready room, tossing their empty bulbs down the washer chute on the way. The ready room’s door shut behind them with a ratcheting sound.

“I’m going to have to fix that thing,” Greg said for what seemed like the hundredth time.

Heron didn’t bother to reply; there were a lot of things on the Buck-Dancer that needed fixing, and a noisy door was at the bottom of the list. He pulled his skinsuit’s hood up over his closely-cropped head and settled its mask over his face. “I’m ready.”

Greg triggered the air pump. Heron’s skinsuit tightened to compensate for the loss of pressure as the pump’s high-pitched whine faded into silence. The heavy door at the end of the ready room slid upwards with a faintly-felt vibration.

They hauled their shells from the ready room over to the drill truck, parked near the bay’s main exit. Weak sunlight slanted in through the open door, barely competing with the overhead lights. They strapped the shells into the drill truck’s open bed and climbed into the cab. Heron’s skinsuit relaxed its protective grip as the cab pressurized, and the vents in his mask opened. The air in the cab was cold and smelled faintly of oil.

He booted the truck’s autopilot and selected their destination. Pale sunlight slipped through the cab as they backed out of the equipment bay. Heron engaged the autopilot. The main rocket motor hissed into life and dust billowed beneath them as the exhaust stream hit the regolith. The truck accelerated away from the surface on a course for the far pole.

#

The truck’s elliptical orbit took them over the terminator, a rough line that split the asteroid into light and shadow along its equator and brought every bump and crater into sharp relief. Greg had dozed off, and Heron was so deep in his thoughts that he did not immediately notice the missile tracks rising towards them from the surface of the asteroid.

Then the motion caught his eye. He stared at the faintly-glowing tracks in confusion, then reached over and flipped on the truck’s radar. Stealth was a fine concept, but he wanted to stay alive. The collision alarm promptly sounded, jolting Greg awake.

“What’s happening?” he asked. “Are we under attack?”

“Sure looks like it,” Heron said. He disengaged the autopilot and tumbled the truck ninety degrees so its nose pointed at the missiles coming up on their flank. Then he waited, watching as the gap between the truck and missiles narrowed.

“Maybe we should do something about it,” Greg suggested.

Heron nodded, his lips moving silently as he counted off the distance.

“Now,” he said, and he lit the truck’s motor with the throttle wide open. The plane of their trajectory rotated towards the radar tracks, and then passed safely above them. There was no way the missiles could change course now with the speed they had built up.

The collision alarm fell silent as the tracks receded behind the truck.

“It’s a mistake to try to run away from an intercept,” Heron commented. “That just gives an attacker time to respond.”

He scanned the console for more signs of trouble. Radar was showing some movement on the surface near the launch site. He levered the truck’s telescope out of its recess in the hull and swiveled it around to look at the launch site. A thin cloud of dust obscured the surface of a deep crater.

“Something’s down there,” he said.

“No shit,” Greg said grimly.

Another volley of missiles rose from the crater’s mouth. Their exhaust lit the dust cloud in shades of yellow and orange. Heron was ready to take evasive action, but motors still firing, the missiles arced back down towards the surface of the asteroid. Cotton ball puffs of dust marked their impact points.

“I don’t get it,” Heron said. “They didn’t come anywhere near us. They didn’t even try.”

“Do we have enough fuel to reach the launch site?” Greg asked.

Heron glanced over at the engineer in surprise, then looked the console over. They were too far past the launch site to reverse course, but they could extend their present orbit and come down by the launch site after they’d overflown the pole.

“We’ve got plenty,” he said. It was a cheap maneuver.

“I want to come up on them low,” Greg said. “Minimum profile.”

Heron shut down the truck’s radar and programmed the course into the autopilot. “You’re sure about this?”

“You said it yourself,” Greg said. “The biggest mistake you can make in this game is to give your enemy time to respond.”

Heron engaged the autopilot.

#

They landed a kilometer from the launch site, safely over the horizon. The landscape seemed hushed when they went outside to get into their shells. The darkness gave Heron the creeps, and he heaved a sigh of relief when his shell powered up.

He unlatched the reel on his waist and plugged its fiber optic line into Greg’s shell. “Ready when you are.”

“Hang on a minute,” the engineer said. He opened the explosives locker and pulled a seismic charge out. It looked like a cartoon bomb, a sphere capped with a cylindrical grip. A battery in the grip powered a shield of molecular superconductors that contained the emissions produced by the charge’s plutonium core.

“Here’s some insurance,” he said, handing the charge to Heron. He pulled out another for himself. Heron clipped the charge to his waist with a short tether.

“All right,” Greg said. “Turn off your thrusters and lock down your tines. We’re going to go in as quiet as we can.”

The engineer took the lead, digging the tips of his tines into the regolith and pulling himself over the surface by his arms. Heron followed, angling away from his partner until they were about ten meters apart. It was not as dignified as walking, but on a low-gravity world it was a lot faster, and it didn’t require the use of thrusters.

It only took a few minutes to reach the lip of the crater that held the launcher. Heron watched, heart hammering, as Greg cautiously looked over the rim.

“All’s quiet,” he said after a moment. “Come on up.”

The dust that had obscured the crater when they first saw it had since settled, revealing a yawning cavern at the bottom of a roughly conical pit.

“Shoot first and ask questions later?” Heron asked hopefully. He was pretty sure he could lob a charge down the throat of the cavern. “A low-yield nuke should take care of anything that’s down there.”

“I want to know what we’re up against before we start shooting,” Greg said.

“How enlightened of you,” Heron muttered. Greg glanced at him sharply, and Heron felt the heat of a flush on his face. He just wanted to be back in the sunlight at the north pole, with the Buck-Dancer’s Choice near at hand.

“You stay here and cover me,” Greg said. “The line should reach as far as I need to go.”

Greg pulled himself over the lip and down towards the crater floor. The fiber optic line snaked after him, unreeling from Heron’s shell. Heron repositioned himself so he had a clear shot at whatever might come out of the cavern. Greg reached its throat and peered inside. He hesitated for a moment, then much to Heron’s discomfort, pulled himself head-first into the opening.

“Damn it, Greg” Heron said, standing up, “don’t do this to me.”

Silence. Heron restrained himself from looking over his shoulder. Stay focused, he thought. If something happens, it is going to happen fast.

“It looks like someone else got here first,” Greg said from inside the cavern.

#

The cavern was full of machinery, much of it wrecked, very little of it familiar. What looked like the remnants of a coilgun littered the cavern’s floor. A missile magazine hulked nearby, its loading train torn apart.

Greg eased a missile out of the magazine. Heron watched apprehensively. If it was salvage-fused, they’d never know what hit them.

“It’s just like the thing that dinged my shell,” the engineer said. “It has a rocket booster instead of a tail, but otherwise it’s the same thing.”

Heron traced the remnants of the loading train into the recesses of the cavern, which appeared to go back quite some ways. In its shadowed depths he could see other missiles in various stages of completion. Looking around the cavern, he spotted stockpiles of components: nuclear batteries, coiled tails, boosters.

“It’s some kind of factory,” he said incredulously.

Greg set the missile down on the cavern floor.

“This is where they’re built,” Heron said. “They launch out of here, and then come down and burrow back in to the regolith. They weren’t shooting at us at all.”

Greg shook his head. “I don’t get it.”

“That second volley wasn’t aimed at us,” Heron said. “It didn’t come anywhere near. Maybe the first volley wasn’t either. Maybe this thing,” he gestured at the machinery around them, “is the mechanical analog of a plant, and the missiles…” He hesitated, disturbed by the implications. “The missiles — and the thing we found near the wreck — are its seeds.”

Greg’s eyes narrowed. “You mean they replicate themselves?”

“Can you think of a better explanation?” Heron fired back. “It explains the readings I got on the way in. If each ‘seed’ contains uranium, then the distribution would vary over time as they disseminate.”

“All right.” Greg held up one hand. “For the sake of the argument, let’s say we’re looking at some kind of self-replicating machinery, some kind of advanced mining system. If that’s the case, why there aren’t there more of them? If they reproduce with any frequency, these plants, or whatever you want to call them, they should’ve taken the whole rock over by now.”

Heron nodded, relieved that the engineer saw the problem too. “That’s right. They should’ve, but they haven’t.”

The engineer’s eyes swept the ransacked cavern. “So… something must be controlling the population.”

Heron nodded again, thinking about the wrecked ship. Maybe it had not been the work of claim jumpers after all.

Greg cleared his throat. “Maybe we should head back to the truck.”

“Fine by me.” Heron moved aside so that Greg could reach the exit.

The engineer crouched below the opening and jumped upwards. Unnoticed by either man, the fiber optic communication line that linked them together had looped around a piece of debris. The line snapped taut, jerking the engineer into a tumble before its plug popped out of his shell. His shell’s communication system automatically switched back to broadcast mode, faithfully transmitting the resulting burst of profanity.

Something moved at the back of the cavern. Heron froze, his eyes straining at the darkness. The staccato cough of Greg’s thrusters cut across the radio spectrum as the engineer stabilized himself.

A robot moved out of cavern’s shadowed recesses. It was easily twice as large as a man, quadrupedal, its massive forelegs clawed for digging. Heron’s faceplate painted a glow of alpha particles over its segmented torso; evidently it was powered by some kind of fission reactor.

The robot’s boxy head swung back and forth as if it were searching for something. The thing’s snout was fluted in the characteristic manifold of a charged particle detector. The lens barrels of its eyes twisted as they focused on him. Heron remained absolutely motionless.

“Sorry about that,” Greg said over the radio.

The robot’s head jerked up. Greg drifted into sight about five meters above the surface. “What’s the hold up?”

The robot reared up on its hind legs, reached clawed forelegs into the throat of the cavern, and pulled itself up into the opening.

Heron swept up the tangled fiber optic and pulled it apart in his hands. The last thing he needed at this point was to get hung up on the end of a line. He reactivated his shell’s thrusters as the robot cleared the opening.

Outside, Greg was noticeably silent. Heron took a deep breath and launched himself through the opening. A snarl of static greeted him as he shot past the robot. It twisted around trying to track him and Greg at the same time.

“Head for the truck,” Greg said.

Heron cancelled his forward motion and lined up on their landing site. His shell’s main thrusters kicked in, snapping his head back against the padded rest. “I’m out of here.”

“On your tail,” Greg said.

Halfway to the truck, Heron cut off his thrusters and spun around to face back the way they had come. Motion in the distance confirmed his fears: the robot was following them. He triggered the mains again and began to decelerate. It was going to be close; while they were slowing down, the robot kept coming at a constant speed, covering the ground with a bounding gait.

They were not going to make it in time. One of them would have to get out of his shell to pilot the truck, and the robot would be on them before then. Heron glanced over at Greg. The glare of the thrusters on his back made it impossible to see his face. Heron increased his thrusters to emergency maximum and dropped out of formation.

“What are you doing?” Greg exclaimed.

“I’m going to distract it,” Heron said. “Pick me up on the way out.”

Greg swore, but it was already too late for him to do anything else. Heron came down right in the robot’s path. It slowed as it approached him. Heron checked his status display nervously. The laser was ready to go, but he was running low on fuel. Just before the robot reached him he jumped and tucked into a roll. He came out of the roll looking back down at the robot. It reared up on its hind legs, watching him.

Heron lined up the cross hairs and carefully shot out its eyes. A scream of static ripped through the radio and it jumped for him. Heron triggered his shoulder thrusters. The robot passed in front of him and Heron shot it again. The beam raked its segmented belly in a glare of light.

“I’m in,” Greg said. Attitude rockets flared on the sides of the truck with a radio-frequency hiss.

Heron hit the ground hard enough to bounce. He regained his feet as the robot landed. Its head swung blindly as it sampled for the alpha particles produced by Heron’s shell. He took aim at its snout but it sprang just as he fired, and the beam reflected harmlessly off its chest. He jumped again, this time a low arc in the direction of the landing site. He caught a glimpse of motion to the side and braced himself for impact, thinking it was the robot on an intercept course.

Greg braked the drill truck with a long burst from its thrusters. “Get in,” he said urgently.

The robot moved so quickly it was hard for Heron to follow. It hit the side of the drill truck and tore off one of its landing legs. The truck toppled in slow motion, twisting from the impact.

“Lift!” Heron shouted.

The truck hit the ground, raising a cloud of dust. Heron moved forward into the cloud. An actinic flash of blue light lit the cloud, accompanied by a snap of static over the radio. The truck’s lights went out.

The cab had been partially sheared off the body of the truck by the force of its collision with the ground. Greg sprawled across the console, maybe unconscious, maybe dead. Heron hesitated, torn between his desire to help his partner and the threat the robot posed.

Another flash of blue light cut through the settling dust cloud. Heron turned away from the cab and climbed up onto the truck’s bed, now turned sideways to the surface. He pulled himself cautiously over the edge of the bed.

The robot crouched beside the truck’s fission reactor. It tilted its massive head upwards and bright traceries of molten metal flowed along the sides of its snout into the manifold’s recesses. Its head dropped back towards the reactor, and the actinic light flashed again. Its ruined eye did not seem to be bothering it much.

Heron lowered himself out of sight. They were not going to fly home. Greg’s shell was still strapped into the bed; Heron released it and let it drop to the ground. He punched out one of the cab’s windows and cleared the ragged edges with a sweep of one stainless-steel hand. Then he pulled Greg out through the opening, careful not to rip his skinsuit.

The telltales set in the periphery of the engineer’s face mask showed that he was still alive. Heron tried to stuff him back into his shell but it was a hopeless task. He transferred the engineer’s unused seismic charge to his own belt. Then he cradled Greg’s limp body in both arms, balancing his weight. He crouched and jumped, triggering the shell’s boosters at the same time.

#

Newport’s World was only twenty kilometers long, and the powered jump put them on an escape trajectory. Heron did not see that as a major problem; he was relieved to be off the surface. When they had gotten far enough away from the rock that he could see the pole where the Buck-Dancer was anchored, he turned his radio back on.

“Mayday, mayday. Buck-Dancer’s Choice, we need assistance.”

There was no reply. He frowned and tried again, then switched to a different frequency. But there was still no response from the ship. Something was wrong, and Heron was afraid he knew what it was. He felt sick with apprehension.

They came out from behind the asteroid’s shadow. Cold sunlight washed over them. Greg stirred in his arms, then came bolt awake, eyes wide with fear.

“It’s all right,” Heron said. Then he brought the engineer’s mask against his shell’s faceplate. “It’s all right. Turn on your radio.”

“I think my shoulder’s dislocated.” Greg’s voice came faintly through the speakers. His face was pale; he was probably in shock.

“We’ve got a bigger problem than that,” Heron said brusquely, hoping to snap him out of it. “The Buck-Dancer isn’t responding, and we’re on an escape trajectory.”

The engineer squeezed his eyes shut. “How much propellant does your shell have left?”

Heron checked his status display. “Not enough to bring us back.”

“What if there were only one person?”

Heron hesitated, then took his friend’s mass out of the equation. The numbers were marginal. “It would be a hard landing.”

“Maybe break a leg, eh?” Greg smiled feebly. “Serve you right.”

“Look Greg, I don’t think this is a good idea.”

“Can’t say I like it much myself,” Greg said. “But you’ve got a shell and I don’t, and there’s not much point in both of us dying. You could get back here before my air runs out. I’ve got another couple hours.”

Heron bit his lip.

“Here’s what you do,” Greg said. He reached across his chest with his good arm and pulled the other one up against his ribs. His breath was ragged over the radio. “Get lined up, then kick me off. The reaction will cancel some of your velocity and save some fuel to soften your landing.”

Heron watched the asteroid spin slowly beneath them. He could not sort his thoughts out fast enough.

“That’s an order, Blue,” Greg said softly.

“Damn it, Greg, I can’t just leave you out here!”

“The sooner you go, the better my chances are.”

Heron took a deep breath. The engineer was right. “Okay. Let’s do it, then.”

“Put my feet against yours,” Greg said. “We’ll push off each other.”

They positioned themselves foot to foot, heads pointing opposite directions. The stars drifted lazily around them. Heron killed their spin when they came around to the right direction.

“I’ll be back,” he said.

“I’ll be waiting,” Greg replied, and Heron could see the engineer’s tight smile in his mind’s eye.

“On zero,” Heron said. He began the count at three.

#

Heron came down a few hundred meters from the Buck-Dancer. He was too late; the ship was down on its side. He hit at an angle and tumbled, breaking a few antennae off his shell, a small price to avoid a broken leg.

An unpleasantly familiar growl of static came from the damaged ship. Heron looked around for cover. Someone waved at him from the wreck that he and Greg had explored. He launched himself on a low, flat trajectory, then skidded to a halt just in front of a tear in the hull. Cole reached out and pulled him inside and pressed his shell’s faceplate against Heron’s.

“Where’s Greg?” he asked, his voice muffled by the layers of shielding.

“I had to leave him,” Heron said. The story tumbled out of him. “We ran into a robot that looked like a big mechanical bear. It took out the drill truck and I had to jump with Greg. I didn’t have enough fuel left to bring both of us back. He’s on an escape trajectory with nothing but his skinsuit.”

“We heard your mayday, but we had our own problems. Sounds like the same kind of thing.” Cole shook his head grimly. “We tried to kill it, but it was too fast. It’s still inside the Buck-Dancer, ransacking it.”

“Where’s the rest of the crew?” Heron asked.

“They’re hiding deeper in this wreck,” Cole said. “We haven’t lost anyone yet.”

“We’re going to lose Greg if we don’t fetch him back soon,” Heron said. “If I could get a jeep out of the mobile equipment bay…”

“No one’s going into the Buck-Dancer while that thing’s inside it,” Cole said. “It would be suicide.”

Heron stared at the captain for a moment, trying to come up with an alternative. Cole was right; in the close quarters of the ship, there was no way a man could win against one of the robotic bears. Heron had been petrified with fear in the cavern, which was probably what had saved him. Even so, the thing knew he was there. If Greg had not come on over the radio, he would have ended up like the dead man they had found in the wreck.

Cole started to turn away.

“Wait a minute,” Heron said. “There’s got to be a way…”

Cole’s jaw knotted, but he refrained from his usual sarcasm.

“I blinded the one that attacked us,” Heron said. “But it could still tell where I was. It has some kind of particle detector that lets it home in on fission reactors.”

“So we’ve got to blind it and disable its particle detector?”

“No,” Heron said slowly, “I don’t think so. I think we can use its particle detector to our advantage.”

Cole raised a questioning eyebrow.

“Lure it out with something that smells too good to ignore.” Heron unclipped one of the charges and held it up. “Something like a seismic charge with its shielding turned off. When the robot comes out, someone goes inside for a jeep –“

“And we blast the robot,” Cole finished.

Heron nodded. It just might work.

#

Heron’s heart pounded against his rib cage as he climbed up onto the Buck-Dancer’s hull. He could tell by the stale taste of the air in his face mask that his skinsuit was having trouble keeping up. He felt naked without the protection of his shell, but that was part of the plan. If the robot could detect the shell’s particle emissions, then he stood a better chance of surviving without it. And even if the suit were punctured, he wouldn’t suffer from decompression; the fabric would bind to his skin and confine the leak. Frostbite, yes, even hemorrhage, but at least he wouldn’t strangle on his own blood.

The ship was silent. He waved at Cole, positioned on top of the wreck. Cole waved back. Harriet waited by the entrance to the mobile equipment bay. Heron took a deep breath to steady himself, then made his way down the spine of the ship.

The engine room had several portholes. Heron padded over to one and cautiously looked inside. The robot was crouched over the ship’s partially-disassembled reactor. It had retracted its fore-claws to reveal a pair of hands that moved with delicate precision over the skeletal outline of another robot, built of parts gathered from the ship.

Heron unclipped a charge from his tool belt and turned its shielding off. The robot’s head swung around and its eyes fixed unerringly on Heron. He sprang away from the hull. A moment later, claws the size of butcher knives punched soundlessly through the plating where he had been. The robot levered its claws and peeled back the plating.

Heron hit the ground and took off running across the crater, trying to stay low. In the periphery of his vision, he saw stroboscopic flashes of laser light.

“Come on, you son of a bitch!” Cole shouted. “Look at me!”

Heron thrust off in a different direction.

“Hah!” he heard Cole exclaim over the radio.

“You get him?” Heron panted.

“I think so,” Cole said. “He’s stopped, anyway.”

Heron dug in his heels and came to a halt after a couple of skips. The robot was casting its head about, trying to sniff him out. It took a step in his direction. Heron turned the charge’s shielding back on.

He circled around the robot, and when only ten meters separated them, turned the shielding off again. The robot’s head jerked towards him. Heron lobbed the charge at its face. The robot batted at it, deflecting it down into the dust. It pounced on the spot where the charge had landed and came up with it in one hand. The ceramic shielding was designed to withstand abuse, but it crumbled in the robot’s grasp.

Heron armed the remaining charge and leapt towards the robot. He landed on its back and it jerked upright. He searched frantically for a way to attach the charge’s tether, but its back didn’t offer any holds.

The robot levered first one elbow back and then the other, fast enough to dismember a man. Then it started to roll over. Heron jumped off; he’d had enough. He triggered the charge and rolled it underneath the thing. He had set it to detonate in sixty seconds. If he did not reach shelter before it went off, he was going to fry.

He ran for where he had left his shell.

“He’s moving off,” Cole said over the radio.

“Count from five,” Heron said. He skidded to a halt, raising a plume of dust, then turned back towards the robot. It had already eaten the bait and was lumbering back towards the Buck-Dancer. The active charge was nowhere to be seen, probably buried somewhere in the dust. He swept the scuffled area with his hands until he found it.

“Fifteen,” Cole said.

Heron pulled the charge’s tether out straight. It looked long enough to fit around one of the robot’s legs.

He caught up with the thing easily enough. His heart hammering, he reached around its back leg with the end of the tether and snapped its clip back over the line to form a loop. He yanked it tight and the robot stopped abruptly.

Heron let go of the charge and ran.

“Forty-five,” Cole said. He jumped down from his position on top of the wreck. “You’re not going to make it.”

“Get out of the way,” Heron panted. The air in his mask was foul.

Cole did not bother to reply. He swept Heron into his arms as he tried to pass and, holding him against the front of his shell, turned his back on the robot. The charge went off with a light so bright that even its attenuated reflection dazzled Heron through his eyelids. Cole grunted as if the air had been driven from his lungs. He released Heron, his face chalky.

“Shrapnel,” he whispered. His knees buckled.

There was nothing but a small, glassy crater where the robot had been. The side of the wreck that faced ground zero was white with dust blown against it by the blast. When Heron blinked, the afterimage of the blast was lurid against his eyelids.

He rolled Cole over. A small hole had been punched through the back of his shell. Frost surrounded its edges, all that remained of the air that had rushed out of the shell. Luckily, the captain had his skinsuit on. That would keep him alive if he did not simply bleed to death.

“Linda, you better get out here,” Heron said. “The captain’s hurt.”

“I’m on my way,” the medic’s voice came over the circuit.

Heron popped the shell’s hatch and dragged Cole out. Blood bubbled on his back, bubbled and froze into fragile crystals. Heron felt dizzy. Blood baubles, he thought. They spiraled down to the ground, ice shot through with sunlight, perfectly silent except for the ringing in his ears. He fumbled in his repair kit for a patch.

Linda appeared beside him. “Are you all right?”

Her voice was full of echoes. Heron wanted to tell her about the patch, but he couldn’t find the breath to speak. The last thing he saw before his eyes rolled back into his head was the exhaust trail of the jeep heading out.

#

Heron woke up in the Buck-Dancer’s sick bay. Examination tables hung crazily on the wall beside him. He took a breath and cold clean oxygen burned his throat.

Linda took the oxygen mask off his face. “Better now?”

“Hell of a headache,” Heron mumbled. He sat up and the scene righted itself. The Buck-Dancer was still over on her side, and what should have been the floor was now a wall. “How long was I out?”

“An hour or so,” she said. “I had to stabilize the captain first.”

“How is he?”

“He’ll be under for a few more hours at least,” she said. “He’s going to have to buy a new kidney when we get back to Ceres.”

Heron felt relieved; the man had saved his life, after all. He rubbed his forehead with icy hands. “What about Greg?”

“He’s trying to restore power so we can get out of here,” Linda said.

“He’s here already?” Heron swore to himself as he pulled off the straps that held him to the stretcher.

Linda drifted back, a concerned look on her face. “Now wait a minute…”

Heron brushed by her on the way to the door. He had to get to the engine room before Greg did anything rash.

The ship was noisy with crewmen repairing the damage done by the robot. As Heron went by, they exchanged glances and laid down their tools. By the time he had reached the engine room, an unnerving silence filled the corridor behind him. Harriet stepped out and blocked the doorway.

“Blue,” she said, and Heron cringed inside, expecting the worst, “that was a damn fine job.” She picked him up in a bear hug, and the corridor rang with a ragged cheer from the assembled crew.

“We all owe you one,” she said, setting him down. “You need to get something done, call me. I’ll make sure it happens.”

Heron nodded, blushing deeply. The corridor came alive again with the rattle and clank of tools. He found Greg bent over the Buck-Dancer’s reactor and the strange machinery that surrounded it. The pose reminded Heron of the robotic bear, intent on its creation, and he had to laugh at the association.

Greg straightened up and turned around. His arm was in sling, but otherwise he appeared to be in good shape. His scowl turned to a smile when he saw it was Heron. Then he scowled again, his good hand on his hip. “What’s so funny?”

Heron shook his head. “Nothing. It’s good to see you, is all.”

Greg nodded slowly. “Likewise Blue, likewise.” He looked over his shoulder at the robot’s skeletal construct. “It was reproducing itself, wasn’t it. Using the ship as a womb.”

Heron nodded. “This asteroid — it’s an artificial ecosystem, with both prey and predators. So far as the bears are concerned, a ship like ours is just another parts supply, easier to get to than a seeder plant. They probably see people as competitors, to be driven off or destroyed.”

“I almost hate to tear it down,” Greg said. “But we need to get out of here.”

Heron had expected as much. He began his argument carefully. “I agree that we’ve got to lift before another one comes along. But I’m not sure we should tear this one down.”

Greg’s eyebrows rose in a silent question.

“It used the Buck-Dancer’s reactor as a core, right? Well, that implies that seeder plants have something like a reactor core too. If we could find them and dig them out like the bears do, we’d make out like bandits.”

“Yeah,” Greg said, “and so would the bears. We’ve been lucky so far; no one has died. But it’s just a matter of time.”

“Well,” Heron said quietly, “if you can’t beat them…”

#

The crater smelled like uranium to the bear. Heron concurred, and together they moved in for the kill. The seeder plant sent up a fusillade as they tore at its shaft, but the bear was expecting this response. It dodged away when it felt the coilgun’s launch field tense and the missiles went by harmlessly. The bear tore at the shaft again and its claws broke through the superconductive cladding with a shower of sparks. Heron shared its fierce exaltation.

Soon they were inside the main chamber. One swipe disabled the seeder launch mechanism, but when the bear turned towards the back of the cavern where the reactor was located, Heron activated the inhibitor Greg had implanted in its nervous system. The robot stopped and swung its head, looking for the source of what was bothering it. Heron keyed in a light-attraction circuit. Reluctantly, the beast climbed out of the cavern.

“We’re in,” Heron said. He put the robot into a dormant state and switched off its sensor feed. His projection visor cleared to reveal the Buck-Dancer’s bridge.

“You’re sure it’s safe down there?” Cole asked.

Heron shrugged. “At least until another one comes along.”

Cole dispatched the recovery team down to the surface.

“If they’re all this easy,” Greg said, “we’ll have more high-grade uranium in a couple weeks than we could get in a year, mining hard rock. We’ll have to come back for the rest.”

Cole nodded absently. “You know, I bet we could wipe them out. Bait them onto the surface with a reactor, then nail them with an anchor.”

“Probably so,” Heron said, stretching hugely in his seat. It had been a long day. “But if we leave some alive, we won’t have to worry about claim jumpers moving in while we’re gone.”

Cole looked at him sharply and then he laughed, shaking his head. “You know, Blue, I didn’t think you had it in you.”

Heron smiled to himself. It was all going to work out fine. He turned the bear’s sensor feed on and got back to work.

– Copyright © 1993 Doug Franklin