He heard Brennart chuckle softly. "You like it, eh?"

"It's terrific!"

Neither Greenberg nor Rhee said a word. Doug wondered how Bianca was taking the flight. At least they weren't weightless for more than a few seconds at a time; Brennart kept goosing the little rocket engine, pushing them higher in short spurts. But the lurching, spasmodic flight was starting to make Doug's stomach gurgle.

Brennart took the little hopper up above Mt. Wasser's flat, U-shaped summit, looking for a safe place to land, checking the actuality against the satellite photos they had studied.

"Flat area over to the left," Doug said. "About ten o'clock."

"I see it," said Brennart.

A minuscule puff of thrust from two of the maneuvering jets set along the corners of the platform and they slid over sideways until they were just above the relatively flat area. It was clear of boulders, although Doug saw the sharp-rimmed edge of a crater big enough to' swallow their hopper, clearly etched in the harsh sunlight.

His stomach told him they were falling. Then a burst of thrust. Falling again. Another burst, lighter, and Brennart put them down deftly oirihe bare rock.

It was like being on the top of the world. Doug unhooked his tether and pulled loose of his foot restraints, then turned around in a full circle. All around them stretched peaks of bare rock, as far as the eye could see. They seemed to be floating on a sea of darkness, the land below them in perpetual cryogenic night.

"We made it." Bianca's voice sounded breathless in Doug's helmet earphones.

We're up higher than Mt. Everest, Doug thought.

"Let's get to work," Brennart ordered. "Stavenger, I want you to record every move we make. Hop down and start taping us as we unload the nanobugs."

"Right," said Doug. He slapped down the railing and jumped from the hopper's platform, floating gently to the bare rock. His boots slid; the rock was smooth as glass.

Pulling out his vidcam, Doug put its eyepiece to his visor and was just starting to record when Killifer's voice grated in his earphones: "Killifer to Brennart. We just received word that a solar flare broke out at seventeen-twenty-six and forty-one seconds. Moonbase advises all surface activity be stopped and all personnel seek shelter immediately."

MOONBASE.

Greg asked, "Are they going to be all right?"

"Brennart's as experienced as they come," said Jinny Anson. "He knows how to take care of himself and his people." But the worried frown on her face belied her confident words.

They were in the base control center, a big low-ceilinged room crammed with control and communications consoles. Every pump, valve, airlock hatch, air fan, sensor, heater, motor, and other piece of equipment in the base and outside on the surface was monitored from the consoles and could be manually controlled whenever it was necessary to override the automatic programming. One whole wall of the darkened, intensely quiet control center was an electronic schematic map of Moonbase, glowing with colored lines and symbols that showed everything in the base and its environs.

Anson had rushed down the tunnel from her office, with Greg in tow, the instant she heard that the flare had erupted. The focus of the center was a U-shaped set of communications consoles, with a trio of operators sitting within fingertip touch of a dozen different display screens. On those screens Greg saw several sections of the underground base, mostly labs and workshops, a lot of plumbing and pumps, and one chamber that looked like a hydroponics farm. There were also views of the surface outside on the floor of Alphonsus. The transfer rocket that had brought Greg to the Moon still sat out there, unattended. Tractors were pulling into the main airlock, trundling slowly across the crater floor to get into the garage and safely sheltered from the expected radiation cloud.

One screen seemed to be looking in on an office Earthside.

Greg could see a window with trees outside, behind an earnest-looking middle-aged man n a tweed jacket.

Anson pulled up a spindly wheeled chair at one end of the consoles and worked the keyboard there. Hie tweedy graying man's face appeared on her screen.

Standing behind her, Greg tried to figure out where on Earth he might be. Then he noticed a saguaro cactus poking its stiff arms into the bright blue sky amid the trees on the hillside beyond that window. It had to be Arizona.

Noticing him behind her, Anson handed Greg a headset.

"... Class Four," he heard the man saying as he slipped on the earphone. "Almost a Class Five."

"Yes," Anson said, "but will it hit the Earth-Moon region?"

"Still hard to tell, Jinny. If we had warning satellites inside Mercury's orbit, as I've been begging for over the past ten years we'd be getting data right now. As it is, we'll have to wait for the plasma cloud to reach Venus's orbit before we get any hard numbers."

"How long will that take?" Anson asked.

"Judging from the microwave measurements, about another two hours."

"It's moving fast, then."

"Faster than a speeding bullet."

"Okay, thanks. Keep us informed, please."

The gray-haired man nodded. "Certainly."

Anson blanked the screen, then turned to Greg. "Well, they've got at least a few hours before the heavy radiation hits. If it hits at all."

Greg asked, "It might miss us altogether?"

"There's a chance. The flare spits out a big cloud of plasma, mostly very energetic protons. Bee ee vee protons."

"Bee ee vee?"

"Billions of electron volts. Killer particles. Fry your butt in a few minutes."

Doug's out there, Greg said to himself. He hardly knew his half-brother. Over the past eighteen years he had seen Doug in person fewer than a dozen times, and then always with their mother between them.

"A couple meters of dirt is enough to stop the particles," Anson was assuring him, "so as long as they're inside the shelters they've dug they'll be fine. Just like we are."

"But you said the cloud might not even reach here."

She nodded vigorously. "The cloud's a plasma; ionized gas. That means it's steered by the interplanetary magnetic field. The field is weird; it gets all looped up and tangled by the Sun's rotation. So until we start getting radiation data from the satellites we've got between us and the Sun we won't really know if the cloud's going to come our way or not"

Greg murmured, "I see," as he watched Anson's face closely. " She was telling him pretty much what he already knew about solar flares, but to her this was no dry astronomical colloquy. This was as real and vital to her as breathable air. "They'llbe okay," Anson said, trying to smile. "Your brother "will come through this fine, I betcha."

"Of course he will," Greg said, wondering if that's what he wanted. Doug's only eighteen, he told himself. He's no threat to me. But another voice in his mind countered, Not yet He's no threat at present. But he's out there on the Moon's surface getting experiences that you've never had. Sooner or later he's going to challenge you for control. Sooner or later. And Mom will be on his side. You know that. She'll be helping him.

"Hey, he's going to be all right!" Anson repeated, mistaking Greg's withdrawn silence. "Really! You'll see."

"Of course," Greg said.

"Come on." Anson got up from her chair. "There's lots more to see around here."

"Now?" Greg asked, surprised. "With the flare and all?"

"Nothing we can do about the flare," Anson said, almost cheerfully. "It either hits or it doesn't. In the meantime there's a lot for you to learn about and not much time to get it all in."

"But I-"

I'm not going to miss my own wedding because you haven't been completely briefed," Anson said. She was smiling, but her tone was far from gentle. "Come on, we can start at the water plant"

Feeling just a little dazed, Greg followed her out of the control center and down the long tunnel.

"We've got to go all the way down to the end and then cut across, Anson said.

Feeling awkward," almost embarrassed in the weighted boots, Greg asked," 'Aren't there any cross tunnels? Besides the one up at the main airlock?"

"Two," replied Anson, "but they're for emergency use only. They carry piping and electrical lines."

Greg glanced up at the color-coded pipes and electrical lines running along the ceiling of the tunnel. "You mean that everybody has to walk the length of one tunnel to get to the next?"

"That's what they're supposed to do. Officially."

"And in reality?"

She grinned at him. "They take shortcuts."

"Then why don't we?" He made himself smile back at her.

"It's kind of cramped."

"I'm not afraid of getting my coveralls dirty," Greg said.

She seemed delighted. They ducked into the first cross-tunnel and Greg saw that it was indeed narrow and low enough to make him keep his head down. But he followed her along its dimly-lit length, noting idly that a fat person would have a difficult time squeezing through. Anson was not fat. She filled out her coveralls very nicely, but she was certainly not overweight.

"The EVC is all the way at the back of the base, as deep inside the mountain as we could put it," she told Greg.

"EVC?".

"Environmental control center," she explained. "That's where we regulate the air's CO2 content, the temperature and humidity and all. It's not a hundred percent closed-loop, though. We have to add oxygen and nitrogen from time to time, keep the balance right."

"Oh," said Greg.

She went on, "We wanted to get the maximum of protection for the EVC. We can go for a couple of days without water, but if the air goes bad-blooey, everybody in the base is dead in an hour or so, I betcha."

"But the water plant's up front, near the main airlock?"

"Yeah," Anson replied. "Plumbing's easier that way. Cost an arm and a leg to dig the EVC in so deep. We had to run big exhaust tunnels through the solid rock. Corporation decided once was enough, so when we built the water plant we put it where we had easy access."

Greg nodded. He knew all about the exorbitant costs of digging new living and working spaces on the Moon.

"I've been talking to some people at the University of Texas." Anson said, "where my husband-to-be teaches. They think our water recycling system might be useful for big cities like Houston and Dallas."

Really?"

"Really." Anson said, with just a hint of sarcasm at Greg's doubting tone. I'll be talking with some people from Houston when I get back Earthside."

Despite himself, Greg was impressed. "You could start a whole new product line for the corporation," he said.

"Water recycling systems for major cities," Anson chirped happily. "We could make a mint on it, I betcha."

Once in the adjacent tunnel she led him to its front end.

"Main airlock is through that hatch." Anson pointed. "That's where we garage the tractors and decontaminate surface equipment."

"Decontaminate?"

"Vacuum off the dust, mostly," she said, leading him away from the hatch. "Freakin' dust gets into everything, especially moving parts. It's a real pain in the butt."

They walked along the front face of the tunnel until they came to another airtight hatch. Greg saw WATER FACILITY stencilled on the smoothed rock wall next to the metal hatch. Beneath the neatly stencilled letters someone had daubed in orange dayglo. You make water; we make water. And over the hatch, another graffito: Recycling is a piss-poor way of life.

"You leave them there?" Greg jabbed a finger at the graffiti.

With a half-smile Anson replied, "We scrub them off every now and then. Matter of fact, I was going to have the whole base cleaned up in your honor, but you got here too quick. These are new, though."

Greg snorted with disdain.

"Don't knock it too much' Anson said. "Graffiti help people let off steam. And cleaning them up takes water that's better used for more important things. Like living."

He kept his silence as Anson showed him through the maze of pipes on the other side of the hatch.

"Everything in here is fully automated, so it's not built for human comfort. Operators monitor the equipment, of course, but it runs by itself most of the time."

"You need access for repair personnel, don't you?" Greg asked.

"Sure. This is it, where we're walking."

The chamber was dimly lit, its ceiling oppressively low. Narrow walkways threaded through the convoluted piping. The place felt cold, but not dank, as a cave on Earth would. The pipes were all wrapped in insulation, Greg saw. Not a molecule of water was being wasted.

"Oxygen from the nanoprocessors comes in there," she stretched an arm toward the shadowed recesses between the largest pipes, anodized green. "It's in gaseous form, of course. Hydrogen comes in along those red lines. They're mixed in those vats and the water is pumped out to the rest of the base along the blue pipes."

"And the yellow pipes?" Greg asked.

"Used water coming in for recycling. Never eat yellow snow and never drink from a yellow pipe."

Greg nodded in the shadowy dimness. Grinning, Anson seemed to be waiting for a reaction from him. After a few moments, though, her grin faded and she resumed her explanations.

"Hydrogen's getting more and more expensive," she said.

"How come? The nanomachines-"

"We have to go farther and farther out from the base to find hydrogen. We've picked the regolith clean of the stuff nearby."

"Really?"

"Hey, we're talking about individual atoms trapped in the regolith. There's just not that much hydrogen out there. One hundredth of a percent, by mass, tops."

"Still, the cost should be negligible."