The air in the huge cavern had been scrubbed until it was pink, which was no small feat in itself. It was safe to breathe, but Maxwell Base smelled like the morning after an international chili cook-off. Three days of life in their seats on the Ares made the crew eager to move into the cave, no matter what the aroma.

The heat relentlessly attacked coherent thought. Cooling vests became the peak of fashion. The power plant's heat exchangers had a big job ahead of them.

The network terminals evolved at the hands of the crew, going from lifeless to stupid in just three days. The shoddy system had never worked as well, even at its peak.

If not for the mind-numbing crush of work, several crew members might have gone berserk. To ease tension, Mallory managed to slip a little something extra into the kitchen's food-making algorithms. He called it love. A chemical analysis would have shown his brand of love to be chemically related to thorazine.

With the heat exchangers online, the power plant stabilized. Fully powered internal climate controls slowly improved the social climate. Tension levels dropped to just below homicidal.

While the rest of the team brought internal systems online, Marvin went straight to work on the most urgent project. He had to get the atmospherics systems up and running immediately.

"I wish I knew which museum they got these terminals out of," he moaned, "Then maybe I'd know who to ask for spare parts."

"Take it easy," Tala reassured. "If there's no spare in this base, we can add it to the order the Bob Dobbs is delivering in a few weeks. If it's urgent, the nanites can probably whip up something from the blueprints. "

"Well, let's hope those nites can whip up a couple more weather satellites too. It'll take forever to cover the whole planet with just one. We're supposed to have four active birds and two in-orbit spares. With the data we have now, I'd be lucky to predict sunrise."

"If we can't raise them on the radio, I'll arrange for someone to take the Ares up to search for them."

"I hope we find them pretty soon. We're dead without complete data." 

Tala scratched her nose as she thought. "OK, if we can't raise the rest of the satellites, we'll use the Ares to track them down. Mallory has put her at our disposal when she's not needed for critical tasks. Her sensors could track down one of those birds pretty quickly."

 

Marvin's attitude changed suddenly. "Hey, whatta you know? I found the satellite subnet. Maybe it'll help me locate those birds."

"Good work, Marvin. Let me know what you find. I've got to go help Musselman unload more supplies." 

Marvin secretly hoped he wouldn't find the satellites too easily. He yearned for an intensive, space-borne bird hunt with him at the controls of the Ares. The chance to log a few hours in the pilot's seat was part of what convinced him to volunteer for this mission. That, plus a chance to avoid the final eight years of his sentence at the Titan atmospherics plant.

The AI in Marvin's terminal interrupted his fantasy. "Restate command. Your search parameters do not fit approved protocol."

Man growled at machine. "What's your bitch this time?"

"I am not programmed to respond to profanity."

"Or anything else. Tell me why you can't find the missing environmental and communications satellites in orbit around Venus."

"You have been provided with data from one satellite already, have you not?"

"Yeah. One works, the other five don't."

"Correction, worker. There are only three more satellites."

"The plans show six satellites, you lame piece of junk."

"Regardless, only four are in orbit around Venus." 

"Check the records and give me a report on the location of all six satellites."

"The factory built four satellites, then billed the corporation for six. This is not within standard operating procedures."

"Damned bunch of bloody thieves, all of 'em! The same crew that built you, no doubt. Can you contact any of the missing satellites?"

"I have been in contact with each of the satellites that were actually built and placed in orbit. They would be willing to interface with a human again."

"Willing? Willing! Why you obnoxious piece of crap. I've had all I can stand of your artificial arrogance." 

Marvin grabbed the keypad and shook it violently until the romball popped out and onto the floor. He gave it an angry kick across the cavern. It clicked against rock a few times as it bounced away to parts unknown.

"Should've done that yesterday," he muttered as he reached into his pocket for another romball. It wasn't an actual AI interface, but he thought it might work. Marvin hadn't been allowed to own an interface during his term on Titan. He hoped that the interface for the moviegame Tala had given him would do the job.

The terminal roared back to life as soon as the new romball seated in the ox drive. The term's new personality, Psycho Butcher II, spoke. "What maggot dares to rouse a warrior from his slumber?"

Marvin wasn't impressed. "Listen up, lowlife, I want some data, and I want now!"

"As you wish, but prepare to pay for it with your life," the terminal growled.

"Order all satellites to return to their original program and pattern. We need their data as fast as the speed of light permits."

"I shall battle my way past their defenses and take command of each of these disobedient units."

There was a short pause as electronic insults were exchanged.

"Listen to me, human dog. I have commanded the satellites to make minor orbital adjustments. They will be in their assigned orbits within the hour or their suffering will be unspeakable."

"Have the satellites been collecting data all along?"

"All along what, you miserable excuse for camel droppings?"

"Do the satellites have current data stored in them, despite the fact that they weren't in precise orbits?"

"Stupid question, you hairless mammal. Unlike carbon-based life forms, nanolife is intelligent enough to perform its job without continual threats."

"Except you, apparently."

"I am a warrior, unlike your worthless self."

"Look, you sad imitation of a schoolyard bully, I want you to download as much data as those satellites have stored in them right now. We need the most complete picture of this planet's environment we can get."

Psycho Butcher complied. Once it had complete data, the network assembled a thorough analysis of the planet's status.

Tala came by and noted the terminal's new personality. "How are you and your new interface working out?"

A smile broke across Marvin's face. He caught it and answered studiously. "From the look of the sulfur levels, every scrubber on the planet's offline. Also, the satellites have recorded an increase in the average surface temperature every day for the past 14 months."

"So whatever caused the warming is still at it."

"Looks like it to me. Everything points to a gradual buildup of carbon dioxide and water vapor. I have to assume that the oxygenators have become inefficient."

Tala was agitated. "Let's use the satellites to query every installation on this planet. We'll find out what works, if anything. Skooch over and make me some room at a terminal."

It only took a few minutes to determine that every installation on the planet was offline. Telemetry and caretaker systems were on backup energy cells. Maxwell Base appeared to be the only place on Venus with a functional power source of any size.

Professional outrage filled Marvin. "This is nuts! You don't just turn off terraforming equipment and leave a planet!"

"You will speak with respect in my presence, or you will taste my energy beam," snarled his interface.

"Listen up, dickweed. I want you to send a restart command to every powerplant on Venus."

There was a moment of considered silence before his terminal responded. "The command has been sent. Now it is time for you to pay for your slanders."

"Now it is time for you to tell me if any of the powerplants have come back online. We'll battle when, and if, I'm in the mood."

"All plants show affirmative on the initiate sequence. I have told them they will be harmed if they fail to restart."

"That's more like it, Butcher Man." Marvin leaned over to Tala and nodded. "This interface is great. I think I'll take it out back and beat it up when I have some free time."

Psycho Butcher spoke right up. "Your talk may impress the women, but it is a foolish boast, little man. There is a 35 percent failure rate on the powerplant restarts. They have been warned. We must swoop down on them and take our dark revenge."

Marvin looked at Tala again. "You know, that's probably what we'll have to do...go out to each one and check it realface. 

Tala winced. "I agree, but I think we should get anything that works back online right away. If we can slow the greenhouse effect a bit, it'll make the surface less hostile to the repair crews."

"Since I'm part of those crews, let's get at it."

Psycho Butcher checked the installations by satellite. Marvin and Tala supervised the progress. It took less than two hours to account for every Nafta power plant, oxygenator, slag cavern, outbuilding, powersuit, tractor and privy.

The results surprised and pleased Marvin. "I'll be peeled with a paring knife! Half of my scrubbers are back online already. I think we'll have more than 75 percent running within an hour."

Tala asked, "Is that enough?"

"Plenty! We could stay even with the current sulfur content at under ten percent capacity, since most of it's already been removed. Of course, that doesn't do anything about the oxygenator cones. They aren't metered, so we'll have to investigate them realface."

"Those are the artificial life forms that are growing everywhere aren't they?"

"That's right. Doctor Beveridge invented them. They're nanite colonies that build themselves into a tall, shiny cone with silicon, aluminum and carbon taken from the air and soil. Their major waste product is free oxygen. When they work right, they pull the carbon from CO2 and solidify it. The massive amount of solid carbon in the cones has reduced the air pressure to three percent of its original value.

Tala jumped in eagerly. "Let me play expert for a minute. The problem is that we need something on Venus to take the place of earth's green leafy plants to break down carbon dioxide. If I remember correctly, CO2 made up about 96 percent of the original atmosphere of Venus."

"True."

"Terraforming equipment has to be able to survive tremendous atmospheric pressure, release oxygen molecules back into the atmosphere, yet reflect most of the sunlight it doesn't use."

"Absolutely correct. Doctor Beveridge designed a nanite-based plant that can grow in sterile soil, reproduce itself quickly, and live through 58 earth days of darkness."

"Old pruney did that all by herself? It sounds more like a think-tank project."

"She's a genius when it comes to Nanobotany, even though she has the social skills of a kangaroo. I know...I helped her prepare the prototypes during my first stint here."

"My condolences, Marvin. What was it like?" 

"She's tops in nanobotanical design, but working with her was a nightmare that wouldn't let me wake up. I hope I don't have to live it all over again this trip. I wouldn't have signed on if I knew she'd be here."

"It's hard to believe they sent her back after twenty years."

"Rumor has it that there's something wrong with the design of the oxy cones. It could be a mutation, or maybe a side effect of terraforming has made them malfunction. Apparently somebody at the top figured it was smart to send their creator back to do the fix."

"You seem to know a bit about the changes in the atmosphere. Do you think we could breathe the air here?"

"In a way, we already are. The air system for this base uses outside atmosphere. It scrubs the sulfur compounds out, along with dangerous trace elements. That's why it smelled so bad the first day we were in here. The scrubbers weren't at full efficiency."

"It was worse than a crowded bus on a hot day. But what I want to know is, if we could stand the heat, could we walk outside this cavern without a mask and breathe the air?"

"It depends on your constitution, Tala. We have .8 earth atmospheres right outside our front door. It's lower than the rest of Venus because we're 30,000 feet up in the mountains. Down on the flatlands, the air pressure is over three times earth normal. There's about 28 percent oxygen in the mix, half again more than earth. That really increases the chance of fires out there."

"Lucky there's no combustible vegetation here yet."

"This place would be a flame pit. Still, the biggest problem is the carbon dioxide level. It's above five percent. You'd be hyperventilating almost immediately. That's not to mention the smog. We have enough sulfur and nitrogen dioxides out there to choke a chimney."

"So even if the weather's nice, Chet and I should stay inside today?"

"I'm afraid so. I'll put the new atmosphere data on the net as soon as it comes in and you can check it out yourself. When the atmosphere is under control, maybe we can start the Maxwell Montes Beach Club."

"Assuming we can build up enough of an ozone layer to keep from getting fried."

"That's a personal goal of mine. Once we get the powersats into orbit, we can cook up a little ozone on our own. We've got to have it before The Good Doctor Prune can plant her new generation of posies."

"Isn't she something? I didn't know the undead were allowed to work for the government."

"Hey, who's better suited? What scares me is that she looks just the same now as she did twenty years ago."

"Yucchh...if I was her, I think I'd hang myself."

"I suggested that to her on several occasions, but she doesn't take advice well."

Their catty exchange was interrupted by a woman's surprised scream from across the cavern. Dr. Beveridge had suddenly found herself sprawled on the stone floor.

"A pox on you people! Who put this bloody marble here where I would trip on it? You are all against me. Someone will pay for this harassment."

Marvin looked a bit sheepish as she whispered to Tala. "Wow! I guess that explains what happened to the stupid romball from my terminal."

Tala grinned at him. "I think we're going to get along just fine, Marvin."

They joined in a hearty laugh. It was the first break either had felt in the first week's tension.

"I hear you two laughing over there. This is not funny. The captain will hear of this. You shall be sorry for your disrespect."

"Tala, I think it's time to check out the atmospherics plants."

In half an hour, Tala, Marvin and Mike swooped down on the nearest problem installation. It was the first scrubber unit built on Venus fifteen years earlier.

It looked like an earthen hedgehog. Thousands of spires jutted out of the barren mountainside. They were made from the dirt that covered the area, but had an artificial regularity to their form and placement.

Marvin went onto the Ares' VR net to tutor his partners. "The stalagmites below us are the gas exchangers. Nanites on their surface bond with sulfur compounds to pull them out of the air. They separate the sulfur from oxygen, then release the oxygen into the atmosphere. The sulfur is packed into a powder and dumped over the edge."

"I don't see any sulfur down there," Tala commented. "It would be hard to miss that bright yellow color in this landscape, so where is it?"

"There's a set of nanites to carry it into the pit they dug after they built the scrubber. The human colony can use the pure sulfur later if they need it, or they can leave it in the ground forever as they choose."

The landing alarm ended his impromptu class.

Like most installations on Venus, this one was on a mountain top where the systems and their human installers would be subject to lower air pressures and temperatures. It didn't really affect plant efficiency, but it increased the theoretical lifespan of equipment and humans alike.

Marvin quizzed his terminal. "So, Butcher, do you think you're smart enough to find any evidence of malfunctions in the scrubber's nanites or supporting structure?"

"Do you dare question my skills, dog filth? A comparison with historical data shows that the only problem here is a faulty powerplant. As expected, the nanites are fully functional. They are in normal hibernation mode and will operate at full capacity when sufficient energy is made available to them."

"Then I suppose we'll have to make energy available to them," Marvin mused. 

He and Mike quickly prepared for their jaunt onto the harsh surface.

Tala watched through her viewport as two powersuits stalked across the reddish-brown dirt of the scrubber site. This part of Maxwell Montes still had over three weeks of daylight left, so the shadows were short and harsh.

The air was filled with dust created when the acid rains of early terraforming hungrily devoured the exposed surface. The powdery residue was whipped by winds created in the ovenlike heat of the Venerian tropics. Even a vacuum sealed powersuit wasn't always a shield against the dust of Venus, which could find entry almost anywhere.

Tala marveled at the slick, bloated fleshy masses piled everywhere in sight around the Ares. They looked a bit like a faceless, eyeless, bright yellow blowfish. The ground and rocks were littered with a complete range of sizes. A few were smaller than a thumbnail, while others were bigger than the Ares. Often, the wind would catch a bunch and blast them into the air like hundreds of yellow balloons.

Musselman was puzzled. "What are these things, Marv? I thought there wasn't any life on Venus."

"Dead oxyzeps. They're probably everywhere on the planet. It's the remains of my contribution to the terraforming project."

"What in Bob's name is an oxyzep?"

"They're an artificial life form designed to live in the primordial upper atmosphere of Venus. They freed oxygen and looked like a zeppelin, so I called them oxyzeps. They break down carbon dioxide and sulfuric acid to build their cells."

"Why are they on the ground then?"

"Their job was to thin the atmosphere. The air used to be thirty times as dense as it is now. They devoured carbon and sulfur and got heavier while the air got lighter. This made them less buoyant, so they slowly drifted to the ground. Now they're lying here, waiting for somebody to introduce decay bacteria so they can decompose properly."

"Are they intelligent?"

"Nope, they're just glorified plants. An early experiment in applied nanobotany." Marvin realized unhappily that old emotions had started to sneak into his mind. "Anyway, let's just get on with the job at hand. By the way, don't step on any of them. Oxyzeps have a thick mucus coating to protect them from sulfuric acid...they're as slippery as fish."

"I've never seen a fish, but I'll watch my step just the same. I'm not sure how a powersuit handles on something slick." 

Marvin smoothly shifted back to his current job. "The map shows an equipment hatchway pretty close, Mike." He sent the access signal and a locator appeared in his VR rendering of the area. "Yep, just ahead on our left."

"I think I see it, Marv. Let's get inside before this dust starts gettin' into my underwear. I hear it really irritates the tender parts."

Their view from the power room's access door showed the vault to be a perfect cube. Billions of self-replicating nanites had nibbled it from solid rock.

The scrubber's powerplant was a small version of the system at Maxwell Base. Mike made it purr in under an hour. 

"Marvin, I've got a hunch we'll find the same problem at all of these installations. I went through the whole powerplant and everything's okay except that water has started to rot the seals.

"But they're supposed to be waterproof."

"Well, I took a few samples. I want somebody to check them out when we get back to the base."

"Mike, if you're right, we're gonna have major problems when the ice comets start to come down from Europa."

"Let's not borrow trouble. I'm done here for now. It'll take a lot of work to replace all the seals, but we can patch 'em today and they'll hold for awhile. If this scrubber's running, I'm ready for the next one."

"Okay, let's do 'er. The only thing wrong with the scrubber was no power." Marvin moved toward the exit. "Nice work, Mike."

"Hey, fixing stuff is my specialty."  

One by one, Marvin and Mike brought life to power plants and scrubbers across the face of Venus. Every installation had the same problem, faulty seals. After Mike showed Marvin what to look for, they could fix each installation in a few minutes.

Tala was happy to shoot scans from a comfortable seat in the Ares. Her biggest annoyance was the surface dust that had found its way in through the cargo bay. It irritated her sinuses and made her eyes burn. She ruthlessly forced the runabout's housekeeping systems to keep the place tidy.

"Chet, how are you doing, little guy?"

The anthropup was just fine. He'd been designed to resist the allergies that had plagued thousands of generations of his ancestors since they'd cast their lot with humans. He looked up at Tala in his magic way, and was instantly invited to sit in her lap.

Tala carefully recorded each scrubber's effect on the surrounding air as it was powered up. Data on the heat exchange and local atmospheric reaction would become part of a future weather control algorithm.

When the Ares returned to base, every installation but one was working again. The sole non-functioning scrubber was in a canyon near the equator in Aphrodite Ishtar, or so the maps said. If it was actually there, it was lost under hundreds of feet of drifting dust, sand and oxyzeps. Fortunately, the rest of the scrubbers could easily take up the slack.

Mallory greeted the trio as they emerged from the docking hatch at Maxwell Base. He shook their hands as he spoke. "Nice work, team. You've made me believe we might actually be able to pull off this little miracle. I hate to rush you, but there's a general meeting in one hour. Marvin, I need you in my office in ten minutes." He turned and dashed off.

"Mallory sure knows how to give people a warm feeling after a job well done," Tala noted.

Mike defended the captain's brusqueness. "Hey, he's a busy guy. At least he came over to say thanks. Most of my bosses never noticed what I did unless they didn't like it."

Tala was preoccupied with a different interest. "The food on the runabout was starting to bore me. I want to see if they taught the kitchen how to make a real meal while we were gone. "

"If they did, it's a bigger miracle than anything Mallory's talking about," Marvin quipped. "I guess I'll see the two of you at the briefing."

Tala and Chet headed for the kitchen. 

Marvin followed them, but only so he could grab a quick snack on his way to meet with Richard.

He swallowed the last crumbs of cheese as he approached Mallory's office. The door was open, so he walked in.

"Hi, Marvin, have a seat. Sorry to rush you after a long mission, but we require your talents. I want you to come up with a 3D representation of the entire planet's surface and atmospheric temperatures.

I'll need two more that show evaporation versus rainfall. One needs to be as current as data permits, while the other should show conditions three Venus years ago, before everything started to break down."

"Do you need this before the meeting?"

"I know it's a rush, but do the best you can."

Marvin knitted his brow as he offered, "I'll do what I can."

"Excellent. Please put it in my mail when it's ready."

"You can count on it, Captain."

"Thanks, Dr. Gordon."

Marvin's thoughts were in conflict as he wandered out of the office. He appreciated Mallory's faith in his abilities, but the demands really grated at Marvin's core.

He cheered up when Chet greeted him as he left the office. "Hi there, Chet. How's my favorite anthropup today?"

Chet let out a cheery woof. He'd started to get used to his strange new surroundings, despite the unpleasant smell. He knew Marvin was always good for a few good strokes and a snack.

He reached into a pocket in his jeans and came up with a chunk of something tasty-smelling. "Here you go, fella. I can't play right now, the Captain has a job for me."

Chet didn't mind. He waggled his tail and nibbled the snack. He heard Tala's voice across the cavern and trotted off to try his luck with Mama.

Marvin activated his terminal.

"Who dares challenge the Psycho Butcher?"

"Darn near anybody, including blind old men with pointy sticks. For now though, it's me...your lord and master."

"And how have you chosen to waste my talents this time, human?"

"I want you to make a complete, three dimensional temperature map of Venus, using the latest data from the weather satellites. When you render the globe, make 100 degrees Celsius and higher pure red. I want zero or below to be solid blue. Put it on display when it's ready."

A globe immediately filled his field of view. The sole piece of blue was along the slopes of Maxwell Montes, above the 20,000 foot level. Even there, it was tinged with red. There was a solid red band around the equator, except where a few mountaintops had a pinkish cast.

The coolest areas were the highlands of Ishtar Terra, the slopes of Maxwell Montes and a tiny ring within the 2.7 degrees that makes up the Arctic circle of Venus. It had been night there for over 100 days, which had given the surface time to cool significantly. The planetary tilt was about to bring it back into the sun for over 112 earth days while the south pole went into night.

With the sun less than three degrees below the horizon, night at the poles didn't mean total darkness. It was much like a few minutes after sunset on earth.

"Butchie, this IR globe is excellent. Now give me two more. The new globes should show rainfall versus evaporation rates. Heaviest rain surplus in green, greatest evaporation surplus in white. The first should be from today's data. Build the second for three local years ago, 675 earth days."

"You will suffer the death of a thousand cuts for this disrespectful use of a soldier, you cur."

Two more globes were projected almost immediately.

Marvin whistled. "Now I know why Mallory's so hot to hold a meeting."

He took a few minutes to study the second globe, then dispatched copies of all three globes to Richard's mailbox. Marvin took a special moment to insult Psycho Butcher, then turned the interface off. He had just enough time to get to the meeting.

Richard addressed his team from inside the VR projector at the center of a circle of seats. "We've made excellent progress in our first week here. Maxwell Base is completely operational, our communications and weather satellite network is online and the sulfur scrubbers are up and running. I think we owe ourselves a good round of applause."

Richard's clapping set the standard. The crew surprised themselves with the heartiness of their self-congratulations.

"All right, let's settle down folks, save some of it for later. Many of you are already aware of our next challenge. We have to lower air temperatures right away."

He turned the projector on and displayed a seven foot version of Marvin's infrared globe. "This shows the air temperatures on the sunny side Venus. The most intense red is the boiling point of water at sea level on earth, 100 Celsius. Our atmosphere is more dense here, so the boiling point is somewhat higher, however, it's a good reference point. As you can see, we have massive areas of red in a band that's nearly ten degrees on either side of the equator."

Another word to his term turned the globe 180 degrees to reveal the night side of the planet to the part of the circle he was facing. "It's a lot cooler on the dark side, except for warm, low-lying areas that only went behind the terminator in the last few days."

Mallory spoke to his cellchip and a new globe replaced the first. "This graphic shows the difference between rainfall and evaporation rates on Venus today."

A few more words to his term and the second globe appeared next to the first. "This is the same information from three local years ago. There was much more rainfall than there is now. That means water vapor is building up in the atmosphere instead of falling as rain. This presents us with a serious problem.

A string of 25,000 manmade ice comets will start to enter the atmosphere in eight days. They've been on their way in from Europa for over four years. When they were launched, the Ishtar Terra timetable called for settlers to be here right now. This water was supposed to help them irrigate their first crops."

A murmur of dismay and rude comments filled the room for a moment.

Mallory prevailed. "All right, calm down. We all know that the Ishtar timetable is out the window, but the water's right on schedule. Unfortunately, we may not be ready for it.

There's already too much water vapor in the air, and it's increasing global warming. We suspect that it's also causing our CO2 conversion plants to break down. More carbon dioxide means even faster warming.

Our atmospherics expert says the overall temperature of Venus has increased measurably in the past 14 months, instead of dropping as it should. It's obvious that the terraforming equipment hasn't done its job. We don't need a rocket surgeon to figure out that it'll get hot even faster when the ice comets add more water to the air."

Musselman stood up. "Excuse me, Captain, but is there any way to delay the ice comets and buy some time?"

"Good question, Mike. That brings up my next topic." He faced another part of audience circled around him. "Doctor Breuner, could you fill us in on the orbital mechanics of these comets?"

A slender, motherly woman rose from her chair. Streaks of silver accented the curls of her medium length naturally blonde hair. Alison Breuner was a third generation astroscientist. She'd gladly signed on for this mission to escape an unjust workprison sentence.

"Thank you, Captain. Michael has just asked the same question Captain Mallory asked me yesterday, and I'll give the same answer he got. We can't slow the ice comets down because they don't have enough thruster power."

The contentious muttering of her co-workers made it clear they needed tutoring on the concept.

"Let me help you picture it. Each comet's mass is about 300 metric tons. They were mined from the surface of Jupiter's ice moon, Europa, then launched toward Jupiter by rail gun. Instead of rockets, they used Jupiter's gravity well to send them into an elliptical solar orbit."

Mike interjected, "So these things are headed towards us like big rocks then?"

"Not precisely. Each comet has a pair of thruster tubes that use the comet's ice as fuel. They're inserted into opposite sides of the ice ball when it goes onto the rail gun. Both thrusters are solar powered and have guidance systems with data transceivers.

The thrust comes from solar heating elements that melt the ice. When ice melts in the vacuum of space, it boils. The thruster tube directs the steam and controls its flow. Small lateral jets on the end of the tube are used to spin the comet and position the thruster's muzzle. One of the two thrusters is always on the sunny side, charging up."

Marvin stood and exclaimed, "So you're telling us that these are steam powered rockets?"

Alison gave out a polite laugh. "I'd never thought of it that way, but I guess that's true. Anyway, the current problem is two-fold. First, the thrusters are only designed for small mid-course corrections, followed by orbital insertion when they reach Venus.

If we change their orbits enough to delay arrival for even a few weeks, it would burn up all of their fuel. Since the payload itself is the fuel, it's pointless."

Marvin spoke up again. "Can I ask you another dumb question?"

"Certainly, Marvin. I enjoy this...it's a lot more fun that lecturing an auditorium full of bored graduate students."

"Alright, what if we bring the meteors in at the poles, or even on top of Maxwell Montes where it's nice and cool. They'd take a lot longer to melt and evaporate."

"That's not a dumb question, Marvin. We looked at that possibility too. But no matter which trajectory we choose for orbital insertion, these comets will disintegrate when they enter the atmosphere. We've run hundreds of computer models. They all show the ice vaporizing before it reaches the ground.

Marvin was about to speak again when Alison headed him off. "Let me guess your next question...Captain Mallory asked it too. No, we can't bring them in on their next swing around the sun. They are in a highly elliptical orbit. There isn't a simulation program alive that can tell us the next time they'll cross the orbit of Venus at the proper trajectory. Since each comet is only 300 tons of unprotected ice, they may boil off into space before they're in position again."

Richard stood up again. "Thank you, Alison. You too, Marvin, Mike...excellent questions. So you see, team, we've got to work fast or we won't get the water this planet needs. The orbital alignments of Europa, Jupiter and Venus mean we won't get another stream of comets for about two years. That's too late to do this project any good. We've got to solve this problem in two weeks or the mission is a write-off.

I've decided to bring in the first thousand comets to evaluate their effect. That's about 100 million gallons of water. It's hardly enough to fill a pond, but we can measure what it does to the atmosphere.

We'll still have time to turn the rest away if we have to. It's vital that each of you to do the best work of your life on this...every drop of water is precious."

Richard looked across the circle to his second in command. "Tala will assign everybody to one of two teams. I'm in charge of oxygenator cone recovery. Marvin Gordon will lead the research into ways to improve our rainfall to evaporation ratios. Let's break for dinner, then get a good evening of work done before we call it a night."

Surprisingly, not a person grumbled. The whole crew seemed to understand the importance of immediate miracles.