They went into the center of the dome, just to the edge of the bomb crater. The plan was simple. Nikki,

being the smaller, Luke camouflaged underneath the rubble, laying shards of wall material over her, with just enough of an opening left to see and shoot through. After, he concealed himself behind a wall and waited. They wanted the aliens to spot his position first and concentrate their fire there. Then Nikki could pick them off.

Luke scanned the jagged top of the dome wall.

"Okay, kiddo. The second they clear the wall, let 'em have it," he said. "And let's hope they come over this side."

One did, one didn't.

Nikki heard, "Oh, dammit!" over her comm as one alien floated into view. She fired, the laser on continuous beam, just as Luke had told her. She waved the beam through the target. The Phinon, caught in the beam, flipped over, returning fire wide of Nikki's position. Then its repulsor was hit and it fell slowly to the surface.

"Bastard got me," Nikki heard.

Nikki flung off her camouflaging debris, jumped up, looking, tense. She didn't understand how Luke could have been hit. Her Phinon was lying in the rubble, flopping and writhing, bouncing in the low gravity.

She spotted the second Phinon. It was hovering over the dome. Luke stood by the wall holding his left shoulder.

His arm was gone. His rifle lay on the ground.

"Luke!"

"We're dead, Nikki," he gasped.

The Phinon had the drop on them. It seemed to be calmly taking in the scene. Or was it? How come I keep thinking of a deer frozen in the road, dazzled by headlights? Nikki thought.

Suddenly, with a flash of suit jets, the Phinon bolted toward its ship.

Nikki rushed to Luke. "Son of a bitch came from the other way. Damn, this hurts!" Luke said. Nikki stood by him, looking at his injury. The suit's trauma units had neatly sealed off the shoulder. Diagnostic lights on the medical display glowed green.

"The painkillers should kick in soon. You're going to live," Nikki said.

"For how long? You've got to stop him, Nikki. You can't let him return to his people."

"You're hurt."

"Don't worry about me, dammit! He's getting away."

"Why didn't he kill us?"

"That's how they behave. Remember the briefing? First in the Oort cloud. And that second ship fleeing from Slingshot."

The remaining alien was still tossing and flopping. "He didn't even help his friend."

"Maybe they don't know what friends are," Luke said, retrieving his laser. Viciously he played it over the downed Phinon. It gave a final convulsion and lay still. Luke whipped back to Nikki. "The joy juice is kicking in. I'll be fine. Take the skiff and go after him!"

Nikki hopped the wall and jumped into the skiff. In seconds she was racing toward the alien ship. The Phinon was easy to find. It wasn't making any attempt to cover its flight, just flying straight and true. In the far faster skiff Nikki drew to within 50 meters. She set the skiff to autopilot. She stood with her laser and took aim.

The Phinon noticed. It dodged, started flying a drunkard's walk zigzag, though still getting closer to its ship. Nikki fired, missed, fired again, to no avail. "It's no use. I'm no marksman. I'm a pilot. So pilot!"

She resumed control of the skiff and punched it. The Phinon never fired, never looked back, as she picked her moment and rammed.

It took the flight out of both of them. The Phinon lost repulsor control, started helixing, flying wild loops. Its weapon went flipping away. It shut off its flight unit and hit the surface, ricocheted, bounced, and skidded to a halt.

Nikki had problems of her own. The collision had wrecked a stabilizer. She fought the skiff for a minute, but it started tumbling. Gear fell out-ration packs, water, and even her laser were scattered away. She finally got the skiff down in one dented piece.

She was between the Phinon and its ship. It was coming toward her, moving fast in long, flat hops, using all four limbs.

Nikki stood her ground.

The Phinon came closer, bearing down, was almost upon her when it took a high hop and tried to hurdle her.

"Oh no you don't!" Nikki said and launched herself in the low gee, the power suit making her a potent

missile. She crashed into the Phinon and held on, gripping him around both legs. The power of her jump

sent the pair in a high arc above the surface.

The alien struggled violently. Though her suit gave her the raw strength of five men, for her it wasn't enough. The alien's steel skeleton driven by organic hydraulic pistons made it incredibly strong.

Protrusions on the limbs where tendon rods connected gave it a huge mechanical advantage. It pried and twisted itself out of her grasp.

It's like wrestling a piece of road equipment! Nikki thought.The Phinon finally kicked itself free and the laws of low gravity ballistics brought them slowly but inexorably to the surface. The alien landed in stride 20 meters ahead of Nikki and resumed the race to its ship. Nikki picked herself up to follow, tried to take a step, fell. Her right leg wouldn't work.

"Shit! Damaged the power couplings." Unpowered, moving her leg was like walking with a concrete

block tied to her foot. She couldn't pursue; her gun was gone. Nikki watched helplessly as the alien reached its ship and entered.

"I'm sorry, Luke," she whispered. "I couldn't stop him."

The tail of the alien craft lit up in a creamy glow. It started to rise on repulsors.

Then her faceplate polarized as a blazing green spot appeared on the side of the ship, remaining there even as the ship accelerated. Two hundred meters up, it exploded. Nikki ducked and covered as shrapnel and debris pelted down around her.

"Got him! Nikki? Nikki? Are you okay? I made it to the laser batteries."

"I noticed," Nikki said. "Good thing. I couldn't stop him, Luke."

"But you slowed him up. That was enough."

"How are you feeling?"

"At the moment, fantastic," he said.

Nikki began her gimpy return to the skiff, taking long, poorly coordinated hops with her functional leg. "I'm coming back to the base," she said. "But it's going to take a while."

"We have the time," Luke said. Then: "Y'know, we could send a message with this laser. We might be rescued after all."

Something high above the surface caught Nikki's eye. A movement. A shimmering line of white appeared for an instant, then was gone. A second Phinon ship going FTL? Running away, the cowards, Nikki thought triumphantly.

It was then that she saw the flickering line of a projectile speeding toward the surface, and intersecting the horizon at the Deepguard base with a cold explosion.

"Luke! Luke!" she screamed into the comm.

To no avail.

II.

Dykstra enjoyed his visits to Sammi's lab. The bulk of his own life had been spent in the areas of physics and high technology, and in those fields it was difficult to find anyone who could teach him something really new. More than once he'd attended seminars by bright, up-and-coming physicists where they'd been trying to describe their latest theoretical approach to some old problem, with all the confident self assurance of youth, only to find that the bright young person had merely rediscovered an idea that Dykstra had heard before, when some other bright young scientist had arrived at the same idea-maybe forty years before.

But outside his own fields he could routinely come into contact with other new stars with genuinely fresh ideas, or at least with ideas that were fresh to him.

Sammi was one of those stars working in the new world of genano engineering. Her name was not known outside her field, not yet anyway. But Dykstra was certain that she'd be heard from, that given time she would inevitably be recognized as one of the top practitioners in the field. He'd seen her type before.

No, not exactly her type, he corrected his thought as he entered the lab, cane gently tapping on the floor. There was something else about Sammi that made her special, something ineffable, but possibly sublime. He didn't know what it was though. Certainly, she had the same shininess of spirit that his dearest friend Jenny had also possessed, and with Sammi he felt that same kinship of similar souls. But there was more, too.

Perhaps much more.

The lab was the same as always, cluttered with high tech nano-manipulating equipment, and every device decorated with fingerprints and odd, sticky residues from spills of those sort of biogoops the biology types dealt with. Dykstra tried to make it down to the lab every few days, particularly since Sammi had a habit of burying herself there.

In the back alcove where Sammi kept her workstation, Dykstra noticed a flickering light coming out of the room's dimness. That would be her computer screen. He walked over and saw the recording of Sammi's experiment with the Phinon femur being played. The scientist herself he found with her face flat on the desk, sound asleep.

Her golden hair lay scattered over the desktop, entangled with a stylus, offering a nesting place to the mouse. Her lips were parted slightly, and even though she was sleeping, Dykstra could see the laugh lines that her smile had long ago engraved upon her face. But there were other lines, recent acquisitions, around her eyes. Lines born of stress and overwork. And grief.

He almost turned around to leave. She needed sleep more than she needed to make conversation with him. He lifted his cane, would walk without it out of the lab. In so doing he momentarily lost his balance, reached out a hand to the table to steady himself, and knocked over a small specimen rack.

"Huh? What?"

"Good morning, Sunshine. Although actually it's evening. Sorry I woke you," Dykstra said.

"Oh, man," Sammi said. "I can't believe I fell asleep. I have so much I need to do yet." She stretched, reaching high above her head and arching her back, which made obvious feminine features which even Dykstra was not too old to notice. "And with big brother watching, too." She gestured toward one of the ubiquitous security monitors. "I've got to get back to work."

"What's that you have playing on the screen?" Dykstra asked.

"That," she said, "is the video record of my latest, circa last week, remarkable success. I hope. Actually, I'm running into some problems I can't see my way around." She explained to him the details of the experiment with the femur, pointing out that she was pleased with the speed at which the bone had disintegrated. "But I can't seem to get the bugs to reproduce properly," she added.

"What characterizes the problem?" Dykstra asked.

"Where do I begin?" she said. "My original bugs were supposed to live in the Martian soil. I've gotten this particular strain of bacteria to live in Phinon tissue, so the viruses can use them to reproduce. Given time and a supply of live Phinons I could probably tailor a virus that will reproduce within Phinon cells, but why not just wish for the Moon?"

"I gather the problem isn't with the virus side of the symbiont?"

"Yes and no," Sammi replied. "I can get ideal reproduction rates of the viruses, but I can't get them to duplicate their tools properly. In a proper setup, the bacteria should live in the Phinon, and the viruses should reproduce in the bacteria, but not just themselves-their tools also. But they won't. To do the femur experiment I supplied them with premanufactured nanotools. The results were gratifying. But they'll have to make their own when they're out there infecting aliens. And I can't see how to get them to do it right now."

Dykstra laid a gentle hand on her shoulder. "What's getting in your way?" he asked.

"I don't know. Stress. Overwork. But mostly it's just that I don't have a live alien to work with. I keep guessing and counterguessing the parameters of the environment the genanites will have to thrive in, and then I rapidly get overwhelmed by the possibilities. The other biologists have their own problems to work on, and I'm still the only genano engineer here." She mock-collapsed back onto the desk. "What am I going to do, Chris?"

He looked at her, and deadpan, said, "I would recommend a party."

"What?"

"Sunshine, you've been hitting it way too hard. It's time you got a break from this. I'm having a small get- together in my suite tomorrow night. Lieutenant Nachtegall will be there, as will Drs. Vander Kam and Arie Hague-"

Sammi shook her head, protesting. "I'm just too busy."

"You're spinning your wheels."

She'd been staring at the screen again, then she turned to him and there were tears in her eyes. "I'm . . .

I'm not ready yet, Chris. I'm just not ready."

"I'm sorry, Sammi," Dykstra said. "But I really have to ask you to force yourself. I need you to come. We have some things to discuss. Some very important things. But I don't wish to discuss them now.""So you need me?" She didn't really believe it."And I also wanted to say good-bye.""You're leaving?!" Her eyes betrayed the look of a child about to be abandoned."For a while, Sammi. Only for a while. I'm going back to Earth. Probably for only several months, if all goes well. Rick and Arie will be going with me. The lieutenant will have to spend some time with us,

too, but he'll be able to travel back and forth."