Donald Moffitt - Mechanical Sky 2 - A Gathering of Stars

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GATHERING

OF STARS

Book Two of The Mechanical Sky

Donald Moffitt

Library of Congress Catalog Card Number: 89-91891

ISBN 0-34.5-36574-7

Cover Art by Don Dixon

e-book ver. 1.0

Grateful acknowledgment is made to Arthur C. Clarke and his agents, Scott Meredith Literary Agency,

Inc., 845 3rd Avenue, New York, NY 10022, for permission to reprint an excerpt from "Space the

Unconquerable" from PROFILES OF THE FUTURE by Ar-thur C. Clarke.

"Try to imagine how the War of Independence would have gone if news of Bunker Hill had not

arrived in England until Disraeli was Victoria's prime minister and his urgent instructions on how to

deal with the situation had reached America during President Eisenhower's second term. Stated in

this way, the whole concept of inter-stellar administration or culture is seen to be an absurdity."

arthur c. clarke

CHAPTER 1

The mullah's knife flashed, and a spurt of arterial blood drenched his white robes. He continued sawing

away at the sheep's throat until he was satisfied, then untangled his fin-gers from the woolly head and let it

drop limply to the plastic sheet that the spaceport janitorial crew had spread to protect the inlaid floor of the

departure lounge.

"Well, you're guaranteed a safe voyage, at any rate," said Hamid-Jones's baby-sitter, an impressively

self-possessed young attaché from the Centauran embassy. "Are you going to go over there to dip your

fingertips for luck?"

"I don't think so," Hamid-Jones said.

Droplets of blood were hanging in the air, settling impercep-tibly in the almost nonexistent gravity of

Deimos. A couple of members of the maintenance crew were sweeping the air with large sponges to catch

stray drops escaping the tarpaulined area, but one jet of blood had traveled twenty feet, and another

cover-alled worker was hurrying to intercept it with a catch basin.

"Wise decision," said the watchdog. "Your ident's as good as we could make it, but it's best to stay in the

background as much as possible till you're safely aboard Centauran territory."

The mullah was winding up the sacrificial rites with a prayer. A number of passengers were

self-consciously lining up for in-dividual blessings.

"What about the person whose place I took?" Hamid-Jones asked.

"He'll be sent back down to Mars in the same diplomatic pouch that brought you up, and we'll do a lot of

computer shuf-fles over the next few months to pass along the hiatus till it's diluted enough to be wiped out.

How was the ride? Uncomfort-able?"

"It wasn't too bad."

The "pouch" had, in fact, been a sealed cylinder large enough to stretch out in. An outer shell was filled

with an inert gas and lined with a lot of sophisticated baffles, some of which projected false images of the

cylinder's interior. An inner suspension con-tained a cocoon that protected the passenger against jolts.

There was a miniaturized life-support facility that provided enough oxygen for thirty-six hours, and a rather

embarrassing sanitary facility that relied heavily on stickybags that would have to be disposed of later by

someone or other. Hamid-Jones had had a few bad moments when the pouch had been dropped or turned

upside-down, but once out of Mars's gravity field it ceased to matter. On Deimos, the Centaurans had

extracted him without being detected.

Hamid-Jones reflectively fingered the curls of his false beard, which was done up in ribbons and squared

off Centauran style. False was not exactly the word, since the whiskers had been force-grown from his

own DNA and grafted, hair by hair, to a three-day growth of his own stubble by molecular machines. A

coppery dye job disguised the disjunction at the roots, which could be presumed simply to be growing out

again and gave him the properly foppish look of a young foreign service officer. He had also sacrificed the

fleshy pad of a forefinger in the unlikely event that a DNA sample might be required at exit; he would have

a sore finger for a few weeks aboard ship as the graft was rejected and his own fingertip, already seeded

for cloned regen-eration, grew out again.

He had balked at losing an eye, even temporarily, and the ambassador had upheld him against the

insistence of the intel-ligence wallahs. "A retinal check is extremely unlikely," the ambassador had said.

"Mars has adhered to civilized standards for over two centuries. The last time they interfered with

dip-lomatic personnel was in the first unsettled years of the usurper, and even then they only checked the

identities of new arrivals, not returnees."

"Don't worry," the attaché laughed. "You look like a proper Centauran. Your build is a plus; it's fortunate

you were born on Earth. The gravity on our capital planet is two and a half times that of Mars—about

ninety-five percent of Earth gravity. You won't have any problems adjusting—our ships boost and deboost

at close to a standard G, so you'll have two years of subjective time to toughen up."

Both of them turned to look at the view outside the huge curving windows of the departure lounge. Lit

from one side, Mars was an enormous breast in the sky, with Olympus Mons for a nipple. The view from

Phobos, of course, was more spec-tacular; there, Mars filled the sky—almost was the sky. But on Deimos,

at least, one had the sensation that one was looking up at it, not in danger of plunging down into it at any

moment.

"Here it comes," the attaché said. "If you look close, you can just about make it out."

Hamid-Jones strained his eyes and was rewarded by the sight of a glimmering mote at the exact center

of the planet. Of course that was the only place it could be—at Mars's equator and di-rectly below, or

rather "above," the tiny moon. Even the east-west and west-east mail satellites, which dropped their own

skyhooks from orbits a little above, or below, synchronous or-bit, were constrained to an equatorial run.

As he watched, the mote grew more bright. It made the 12,000 mile trip up its spider's thread in a couple

of hours, and at about a hundred miles the braking rockets had to cut in to keep it from smashing into

Deimos. Its flattened nacelle shape was visible now. The last time Hamid-Jones had seen it, it had been

un-reeling itself from the Martian sky with a belly full of soldiers.

"It's the last one," the attaché said. "Do you want to board ship before the crush?"

"No, I'll wait," said Hamid-Jones. "I want to see if anyone I know gets off."

"Hmm, yes, there's that," the attaché agreed. "A starship's big, but it's best to see what inconvenient

persons you might have to avoid for the next two years."

"Five years," Hamid-Jones corrected.

"Yes, five to us stay-at-homes. But time will fly for you. The time dilation effect won't be very noticeable

for most of that initial year of boost, but by the time you get up to within about one millionth of one percent

of the speed of light, it'll reach a factor of approximately seven hundred. So you'll do the entire middle part

of the journey—covering some three and a quarter light-years of distance—in what will seem to you to be

about a day and a half. Turnover will take place halfway through that day and a half, and I guarantee that

the captain and crew will be very busy. There's no gravity for several hours—while the ship is coasting

through that appalling void at ninety-nine point nine thousand nine hundred ninety-nine percent of the speed

of light—and I believe the passengers are confined to their cabins for safety reasons. Actually it's to keep

them out of the crew's hair. Then comes deboosting and another year of shipboard boredom."

"You seem to have it all down pat," Hamid-Jones said. He was getting tired of being on a leash, even

when the other end of the leash was held by a succession of scrupulously agreeable people like the attaché.

"Oh, I've given the tour many times," the attaché said. There might have been a tiny shade of resentment

in his tone, too. "There'll be a lecture aboard, I believe, for those passengers who are new to star travel."

Outside in the blackness, a last firing of retro rockets had slowed the hangar-size nacelle to a stop. It

strained at the end of its tether several hundred feet up, like an enormous flattened balloon. The passengers

inside would be technically upside-down—but that hardly mattered in Deimos's negligible gravity. A misty

puff from the attitude nozzles flipped the traveling ter-minal over on its belly, and it started slowly to settle

into its docking cradle. Hamid-Jones's eye was just quick enough to see the flick of the detached tether as it

snaked into its slot beside the cradle.

The stars above were suddenly occulted as the nacelle mated with the departure lounge. Craning his neck

around the curve of the observation window, Hamid-Jones saw the great lid come down and connect the

two structures. He felt a faint vibration under his feet as the lounge rang in vacuum.

"Quite a circus," the attaché murmured as the first embark-ees came through.

Passengers in the lounge stared at the newcomers making their way across the vast floor. At the head of

the throng was a wave front of four-armed dwarfs in gaudy puffed costumes and turbans like fat pretzels.

The little men were laden with suitcases, glad-stone bags, small sea chests, brass-bound coffers—one to

each arm. Many of them were outmassed by their burdens, and though weight was no problem in Deimos

gravity, the dwarf's must have been enormously muscled under their flaring finery to have man-aged all that

tonnage on the surface of Mars.

"Product of Palace bioengineering?" the attaché asked.

"I'm afraid so," said Hamid-Jones. "The Emir always went in for that sort of novelty."

"Handy for carrying a gentleman's luggage," the attaché said dryly.

"They're not a particularly elegant example of gene redesign, like sandipedes or hexapodal camels,"

Hamid-Jones said with professional distaste. "They were created by a rather crude form of somatic

replication—the Palace cloning department uses a lot of shortcuts. They wouldn't breed true if, in fact, they

weren't already sterile."

"That's a relief," the attache said as the little men marched past, the weight of their multiple loads keeping

their buskined feet more or less in contact with the floor. "I'm sure they're much esteemed here on Mars,

but they wouldn't be a very suit-able gift from one sovereign to another if there was any danger of their

spreading."

Hamid-Jones suspected the attaché was making fun of him, but he could detect nothing but seriousness in

his expression.

"My word, look at that!" the attaché exclaimed. "Your Emir certainly does have a taste for these

prodigies!"

Following the dwarfs was a gaggle of four-legged dancing girls in scanty, sequined costumes that left no

doubt of their profession. Their faces were concealed for travel, but the leg-veils billowing below were

gauzily transparent. They moved across the floor like skittish racehorses, their dancers' skills do-ing for

them what anchoring weight had done for the dwarfs. The effect of the double-hipped platforms bearing all

those slen-der, upright torsos was rather like a procession of candles on trivets.

"If one may ask," the attaché said, "does two sets of legs, ahem, also imply two functional sets of other

apparatus?"

"They're capable of bearing children at either fork, if that's what you mean," Hamid-Jones said, annoyed.

"Two in one!" the attache exclaimed. "That truly would be a princely gift from royalty to royalty—if the

recipient had a taste for the bizarre. Our Sultan, however, is a man of uncom-plicated though hearty

appetites. He'll probably pension these dancing quadrupeds off. I have no doubt they'll all find hus-bands.

But did I understand you to say that they're not sterile?"

"That's right," growled Hamid-Jones. "But they carry a sex-linked lethal recessive that goes with the

quadrupedia. So any surviving male children would be back in the genetic main-stream."

After the dancers came a matched set of two-headed singers capable of performing duets with

themselves—the pair of them constituting a quartet.

"What, one wonders, is their repertoire?" the attaché drawled. A lowering look from Hamid-Jones cut off

his further comment.

The amazed stares of the spaceport bystanders changed to admiration as the next offerings of the Emir

filed past—a suc-cession of handlers and grooms with some of the finest animals in the Solar system.

There were prancing salukis, their silky ears flying in the low gravity, held down to the floor only by the

pressure of the leash; fierce, caged Marsfalcons with magnifi-cent plumage.

"The poor creatures will never fly on Alif Prime," the attaché' said, serious now. "Those great fragile

wings would snap like matchsticks at first flutter. They'll have to be sent to one of the moons and kept in a

zoo."

Hamid-Jones's heart stopped as he recognized al-Janah lead-ing the string of Mars stallions being

escorted by Royal Stables grooms. Had someone else—Rashid or Ja'far—completed the cloning project

he'd started? After he recovered from the first surprise, he realized that there wouldn't have been time to

carry a clone to maturity. The horse was unmistakably al-Janah, but he would have to be the product of an

earlier cloning.

"Wonderful animal," the attaché said. "Is something the matter?"

Hamid-Jones turned away. "I hope that none of those grooms can recognize me through this disguise."

"You won't have to worry about them once you're aboard. They'll turn the horses over to our own

stablemaster and return on the next tethershuttle."

Porters with padlocked cases, in lockstep with armed guards, followed the animals, and then came crews

of navvies floating pallets with huge crates, big enough for elephants, a few inches off the floor. Jewels,

perhaps, in the smaller cases. The contents of the crates could only be guessed at. In a previous exchange

of gifts between rulers, the Emir had sent a custom-built state yacht, tested on one of the enclosed palace

lagoons and then dismantled in sections; the Mars-made craft could not have stayed afloat for five minutes

in Alpha Centauri's seas, but as a gesture it was hard to top.

Last of all came the new Martian ambassador and his consid-erable retinue, who were to present the

collection of state gifts. The current ambassador, four light-years away, could have no inkling that he would

be replaced upon the arrival of the star-ship. Even the news of the bogus Emir's "recovery" from the

ambushed operation would not arrive by radio until a year before the ship. The distant ambassador was a

Rubinstein man. He was definitely on Ismail's list. Hamid-Jones wondered whether there was a killer in the

replacement ambassador's retinue, or whether the execution would wait until the old ambassador returned

to Mars.

"Is there anyone in that bunch who might know you by sight?"

Hamid-Jones studied the ambassadorial staff. There were too many eunuchs among them—about fifty

out of a total of a hun-dred or so. The uncastrated men tended toward civil service fops, some of them as

gaudy and overadorned as the eunuchs.

The ambassador himself, a cadaverous fellow with shifty eyes, was not a eunuch—that would have been

an insult to the Sultan— but he was Ismail's man nevertheless. It was more than four light-years to Alpha

Centauri, but fear made a long string.

"I don't recognize anyone offhand, but you never know."

"If worse comes to worst, you can put yourself under the captain's protection. He won't be able to

acknowledge you openly—there's already too much diplomatic strain between Mars and Alpha

Centauri—but perhaps he might tuck you away somewhere. I don't know how many coverts are traveling

with that dressmaker's circus, but it's unlikely that even the loosest cannon would compromise his

ambassador's position with a shipboard attempt on your life." His teeth gleamed in a perfect smile.

"Governments generally hire the Assassins for that sort of skulduggery."

"That's very comforting," Hamid-Jones said.

"There go the last of them," the attaché said, turning. He was a bit of a fop himself, but when his short

Centauran-style chlamys parted, Hamid-Jones clearly saw the outline of a shoulder holster. "You'd better

get a move on. Do you have your boarding pass?"

"Yes."

"Good. I'll leave you here, then. I'm not cleared past the gate. Good trip and all that."

"Thanks."

Hamid-Jones picked up his carry-on luggage and joined the last-minute flow to the departure gate. There

were fewer than a thousand people left. They parted in two streams around the mullah, who was cleaning

up the remains of the sacrifice while an impatient custodial worker rolled up the edges of the plastic

tarpaulin. A number of passengers were pausing to dip their fingertips or pick up a fragment of the

laser-charred mutton. At the last moment, Hamid-Jones did the same, popping a black-ened morsel into his

mouth with a mumbled prayer.

As he moved in a low-gravity shuffle through the long trans-parent passage that curved over Deimos's

small horizon, never more than a hundred yards away, he lifted his eyes with almost everybody else to

watch the rising of the starship above the pocked skyline.

It was a vast onion shape, over a mile in diameter, that would flatten out still further under acceleration.

He could see the gos-samer shroud clinging to the ship and all the complicated rigging and stays that would

unfold it in flight to protect the craft from the howling storm of charged particles that would impinge on it at

relativistic velocities; the superconducting fabric was gaily painted with colorful Kufic calligraphy, though

the decorations would char away long before the ship reached even a fraction of its final speed.

The ship itself, of course, was mostly wood, varnished to a glossy sheen. Wood was the most practical

material for large structures built in space. It didn't have to be lifted at great expense out of the gravity

wells of planets—it was sent spiraling inward from the cometary belt, where the forests of mankind had

been growing for five centuries. The great shipyards beyond the orbit of Uranus fashioned the

comet-grown lumber into starships, space stations, habitats, intrasystem liners—everything except the small

craft designed for atmospheric reentry. The giant trees, bio-engineered to live in a vacuum, subsisted on the

water, carbon, and nitrogen of cometary ice and in the absence of significant gravity grew to immense size.

Timbers a hundred miles long, used in the construction of habitats, were not uncommon.

For a starship like the Saladin, timbers and planking a mere mile or so in length sufficed. Hardly a bolt or

fastener had been used in the Saladin's construction. Like the Arab ships of yore, it was sewn

together—not by coir, as in the ancient seagoing vessels, but by thousands upon thousands of miles of rope

made from monofilament fiber. The stitched construction gave the starship the advantage of flexibility. Like

a living thing, it could change shape and adapt itself to the enormous stresses of con-tinuous one-G boosts

over periods measured in years. Wood and cord were far more sensible materials than metal, which would

have had to have been worked into movable joints, or plastic, which was inclined to deteriorate under

exposure to the shorter wavelengths or, still worse, to snap.

Wood had been an underrated material in the early days of space exploration, but once mankind had

outgrown its tin cans, the engineers had begun once again to appreciate its virtues of high tensile strength,

elasticity, and superior insulating quali-ties. The cedars of Lebanon were reborn—this time in the com-etary

wilderness. Someday, when the spreading ecology had transformed the Oort Cloud, the greater portion of

humanity would live on comets.

"It looks almost like a giant mosque, doesn't it?" remarked an elderly gentleman who was shuffling along

beside Hamid-Jones, holding a bird cage. He peered nearsightedly at the wooden onion with its slipcover.

"Er, yes, I guess you could say that," Hamid-Jones agreed politely.

"And the covering with the sacred inscriptions—it reminds me of the embroidered covering of the Kaaba.

Have you been to Mecca?"

"Er, no, not yet."

"The inscriptions—will they protect us from harm, do you think?"

"Well, uh, when the magnetic umbrella opens up it will cer-tainly protect us from all the hydrogen atoms

that will rain on us at relativistic speeds."

The old man squinted rheumily at Hamid-Jones. "Don't I know you from somewhere? Have we met?"

"I don't think so."

"Just a minute and I'll have it," the old man said.

"It's been nice talking to you," Hamid-Jones said, and hur-ried to leave the old man behind.

A smiling steward was waiting to greet him at the head of the gangplank. He compared Hamid-Jones's

boarding pass to a list summoned up on a palmscreen and said, "Welcome aboard, sidi. A porter will show

you to your cabin. There's plenty of time to get settled—we don't cast off for another hour and a half. I

suggest you go to the observation deck to watch our departure. It's a grand sight. We borrow Deimos's

orbital motion to assist us, and as we pull round on the sunward side, you'll see Mars go through all its

phases in a half hour. A full Mars at only twelve thousand miles is worth seeing! There won't be much to

see after that—Earth will be visible to the naked eye for only about a week, and two weeks after that, the

Sun will be only another star. By the time we reach a third of the speed of light, the stars themselves will

start to disappear—blind spots will appear both ahead and behind as the stars Doppler through the spectrum

and become invisible, below infrared behind, beyond ultraviolet forward. The blank disks will enlarge,

squeezing the rest of the stars between them into rainbow hoops, until there's just a thin band around us.

We ride through a void after that. So see the sights while you can."

"Thanks, I will," Hamid-Jones said.

"Don't worry about acceleration, though. You'll have plenty of time to acquire your space legs. We'll give

you about six hours to get up to a Martian standard G—takeoff's practically unnoticeable—and then we

give the passengers a month to work up to a standard Centauran G. There are exercise programs available

to help. We suggest strongly to all Marsborn passen-gers that they sign up, but if you're Centauranborn or

Earthborn to start with, and you've only lost tone on Mars, the gradual increments of acceleration are

generally sufficient to get you back in shape—though mind you, an hour or so daily in a pen-guin suit can't

hurt."

He was looking curiously at Hamid-Jones. Hamid-Jones re-membered that while he was dressed and

coiffed as an Alpha Centauran and traveling under a Centauran name, his accent was distinctly

Solar—Martian with an underlay of Anglo-Arab. His sturdy frame though, forged in Earth's gravitational

field, had more in common with Centauran physiques than those of most of the inhabitants of the Solar

system.

"I'll keep that in mind," Hamid-Jones mumbled.

The steward snapped his fingers. A porter appeared at Hamid-Jones's side, dressed in blue pantaloons

and a white jacket. He touched his tarboosh respectfully and gently pried the bag from Hamid-Jones's hand.

"Would you like me to carry you, too, sidi?" he said, producing a wraparound girdle with two handles.

Hamid-Jones had no intention of being toted like a log of wood. "No, thank you, I can manage very well in

low gravity," he said snappishly.

"Very good, sidi," the porter said, and launched himself in a flat trajectory, leaving Hamid-Jones to follow

as best he could.

The cabin turned out to be more like a stateroom, with its own tiled bath and a curtained sleeping alcove.

There was plenty of room aboard a starship, the economics of interstellar travel being what they were. The

prayer nook contained a circular rug that perfectly illustrated the nature of star travel with its contin-uous

boost. Instead of a pointed mihrab to align the worshipper properly, the prayer niche was round, with a

circular target for the forehead. Mecca would always be directly below during the first half of the journey,

directly above for the second half.

He washed his face, fiddled with the holovid to see what the ship's library contained, sampled a piece of

fruit from the bowl on the table. A pamphlet told him that the Saladin possessed its own orchards that

were supplied with light in the growth spectra diverted from the awesome glare of the total annihilation

drive, its own flocks of sheep and chickens for fresh mutton and poultry, grew its own garden vegetables

and heterochronic grains—though there were bulk suppliers aboard for a two-year subjective voyage should

blights or poor harvests afflict the hy-droponics cages. There were also several paradises aboard, with

purely decorative trees, flowers, and songbirds. Passengers were cautioned to be careful about letting

songbirds escape when en-tering or leaving through the double doors.

A chime sounded, and a pleasant disembodied voice re-minded passengers that the ship would cast off in

one hour, for those who wished to secure a good place on the observation deck. Hamid-Jones struggled for

the better part of a nanosecond against the desire not to appear overeager and unsophisticated, then

jammed the unfamiliar tarboosh back on his head and joined the trickle of passengers moving through the

corridors. It wasn't every day that one set sail for the stars.

With a groan of protesting timbers that was audible within the ship but went unheard on Deimos's airless

surface, the Saladin cast off its mooring cables and started to rise. Slowly, ponder-ously, like a vast

squashed balloon, it drifted upward on the momentum imparted by the loaded springs of the landing cra-dle.

Once, the gentle nudge had come from compressed CO2, but worried Sufi environmentalists had pointed out

that the mol-ecules tended to linger, even on a body with an insignificant gravitational field like Deimos.

Deimos fell behind, a smallish potato crisscrossed with the glittering threads of enclosed tubeways and

studded with the thumbtack shapes of the hotels and spaceport facilities that had grown there over the

centuries. Two of the potato's eyes were glazed over—Swift and Voltaire craters wore bubbles contain-ing,

respectively, a park and a low gravity recreational lake over a mile in diameter. Somewhere in Swift Park

was a monument displaying a replica of the first Deimos lander, a Russian craft of the early twenty-first

Christian century.

The intrasystem fusion drive kicked in when the Saladin was far enough away from Deimos not to

endanger it. The initial boost was at a gentle one hundredth of a gravity. Within the ship, loose objects,

including people, began to settle to the floor. Water stayed in basins. Flower arrangements in cabins showed

the slightest droop. People weighed a pound or two—more than they had when the ship was berthed at

Deimos.

Steadily, weight increased. In ten minutes it had doubled. At the end of the first hour it was up to about

six percent of a Terrestrial G and still increasing. The ship's modest hydrogen reserves would be used up

long before it crossed the orbit of Jupiter, but by then it would be safe to turn on the Harun drive— at that

point the Saladin would be traveling several million miles below the plane of the ecliptic, no inhabited body

of the Solar system would be anywhere near its path, and the memories of the Solar system's traffic

computers would have been searched to insure that no spacecraft had strayed from the ecliptic on a course

that would risk intersecting the trajectory of the Saladin at close range.

The Harun effect was well understood after six centuries, and there had been no major accidents since

the unfortunate release of the antihydrogen cloud that had wiped the surface of Hygeia clean and turned it

into a ball of fused glass. But one doesn't take chances when one rends the curtain of Creation.

The great wooden bubble, a world in itself, steadied and trimmed until it was aligned with the Centaur.

Once, that con-stellation's brightest star had guided Arab mariners venturing south of the equator by

pointing the way to the Southern Cross. Now it shone as a yellow beacon beckoning toward another of

Allah's kingdoms in the sky.

"I beg your pardon, but could you help me to a seat? I can't seem to stay on the floor."

Hamid-Jones turned his head and saw the old gent who had been carrying the bird cage. He was clinging

for dear life to the backrest of Hamid-Jones's seat; evidently he had lost his nerve while trying to negotiate

his way toward one of the few empty chairs.

"Here, take mine," Hamid-Jones said, springing to his feet and managing to stay anchored himself only by

grabbing a knob on the armrest.

"Oh, I couldn't . . ."

"That's all right. Sitting or standing, it doesn't matter much at a sixteenth of a G. Here, let me help you.

Maybe you'll be more comfortable with the safety belt fastened."

The old man settled gratefully into the cushions. "Oh, you're the young man I spoke to at the spaceport."

"Er, yes." Hamid-Jones started to edge away.

"I was afraid I 'd bounce up too far and fall into that! It makes me quite dizzy just looking at it."

He gestured toward the central well that rose through the mile-wide acreage of the observation deck. It

was a thousand feet across and surrounded by a chest-high railing. It was there to allow for expansion as

the Saladin changed shape, and it was the core of the ship. From the lounge chairs drawn up to face it, one

could look down into a chasm that at present was a half-mile deep, or up to see the destination stars of

Centaurus. Most of the ship's passengers were seated a halfmile away to watch the retreat of Mars

through the ports that girdled the ship, but the more romantically inclined had taken their positions here, to

dream and to speculate.

"Oh, there's no danger of that," Hamid-Jones assured the old man. "If you look close you can see the

safety threads rising from the railing. They're very fine, but you'd have to be really determined to squeeze

through them. The well can't be glassed in, of course, without a lot of expansion joints that would spoil the

effect."

"I suppose one couldn't really get hurt, even if one did fall through," the old man said, pulling at his

snow-white beard. "You'd just float to the bottom."

"Oh, don't make that mistake," Hamid-Jones warned. "You might only weigh nine or ten pounds at the

moment, but that's quite enough to break your neck at the end of a half-mile fall."

"I've been thinking about where I could have met you. Have you ever gone hunting in Tharsis?"

A finger of ice ran down Hamid-Jones's spine. "No."

"Perhaps I'm mistaken. I've catered hunting parties there. My name's Izzah Zarrab." He peered

expectantly at Hamid-Jones.

For an awful moment, Hamid-Jones couldn't remember his Centauran name. "Murjan Khalil Khulafa," he

said with a gulp.

"May your hands be blessed, ya Murjan," the old man in-toned.

"And yours, too, sidi," Hamid-Jones said.

"I could have sworn—"

"Have you traveled to the stars before?" Hamid-Jones inter-jected hastily.

"Ya satir, no! They say that star travel makes you young, or at least you come back not as old as you're

supposed to be, but I don't understand such things. But I haven't the years left to try to find out. I'm going to

live with my daughter. She was taken to Alpha Centauri by her husband, an artisan, many years ago. He's

very kindly offered to take me into his household. That's what the message said, though it took them almost

nine years to answer me." His watery eyes were trying to puzzle out Hamid-Jones's tarboosh and facial

curls. "And what brings you to this journey? "

"Family," said Hamid-Jones, and left it at that.

"When the sky shall split and become doors," the old man said indistinctly.

"What?"

"It's a verse from the Koran. The seventy-eighth surah." The old fellow fumbled with a chain around his

neck and brought forth a charm with a scrap of paper in it. "The mullah gave it to me to protect me through

the splitting. Will that happen soon?"

"Oh, when they turn on the Harun drive? I suppose the sky does split in a way, but not the way you think.

I gather it's more like opening a faucet. I shouldn't think that would be for another day or two. They have to

get up to a certain speed. There'll be an announcement beforehand."

"I would have thought such a thing impious. But the mullah assured me that what Allah allows must be

Allah's way. Do you agree?"

"Yes," Hamid-Jones said, seeing a note upon which to make his escape. "It must be Allah's way."

"More caviar?" the steward said, bending over the table.

"Thank you," Hamid-Jones said. He pushed aside some of the eggplant appetizer to make more room on

his plate.

"There'll be another seating for the lecture after lunch in the small theater on jim deck," the steward said,

spooning out a generous portion and arranging several wedges of flatbread. "There are still a few seats left.

Would you care to go?"

Hamid-Jones wiped his mouth with a napkin. "Yes, I would. I tried to get into the breakfast seating, but it

was jammed."

"The response caught us by surprise. More than four thou-sand passengers signed up—about a fifth of

the passenger list. That's almost twice the usual number. The poor cosmologist and his assistant are giving

five lectures a day, and they've roped in the first officer as well."

"I'll look forward to it."

The steward leaned closer. "I've got you into the assistant cosmologist's talk—frankly, the chief is a bit of

a stick. It should be a little livelier than the ones you missed—if my spies have informed me correctly, and if

the captain doesn't change his mind, we should switch to the mutual annihilation drive some-time during the

lecture itself. So be sure to wear your seat belt."

"Thanks, I appreciate it," Hamid-Jones said.

"Here, let me give you a little more caviar."

"Oh, I couldn't. It's very good, though."

"It ought to be. It was collected this morning. That's as fresh as you can get."

"Don't tell me you have sturgeon aboard?"

The steward laughed. "Our pools aren't quite that oceanic. No, this is heterochronic caviar. It reproduces

itself without an intervening generation of sturgeon. Don't ask me how. You'd have to be a cloning

technician to understand it."

"Uh, I suppose so." Hamid-Jones popped a wedge into his mouth and became too busy to talk further.

The steward smiled at him and left.

The cosmology officer was a stocky young man with smooth rosy cheeks and an air of intrinsic

self-confidence. He was natty in a blue uniform decorated with the triplet of gold, orange, and red stars of

the Centauran service and a specialist's patch show-ing a representation of the universe surmounted by a

Feynman diagram in gold braid.

"You've all heard the announcement, so I won't waste time by repeating it, except to say that nothing

much happens when the annihilation drive goes on. Your weight goes off for a minute or two after the

fusion engines shut down and before the Harun drive cuts in, that's all. Then we'll take about fifteen

minutes to bring the ship up to full thrust again—the drive techs will be fine-tuning the proportions of matter

and antimatter. So sit tight for the first few minutes. You can move around freely for the present, but when

the buzzer and warning light go on, please fasten your safety belts."

"Excuse me—I thought we were supposed to be weightless for several hours," said a nervous passenger

in the front row.

"You're thinking about turnover. That won't happen until a year from now. A year of ship's time, that is.

About two and a half years will have passed for the rest of the universe. We'll have spent the first year of

that getting up to within about one ten-thousandth of one percent of the speed of light. In the pro-cess, we'll

travel about half a light-year. Time will hardly have seemed to slow down at all for us during most of that

time. But when we get to about ninety-nine percent of the speed of light, the relativistic effects will begin to

increase very rapidly, so that at our top velocity, time will slow down by a factor of about seven hundred. In

other words, the remainder of the first leg of our trip after that year of boost—about twenty months at

very nearly the speed of light—will go by for us in less than a day."

"Oh . . . I see . . . it's not today, then?"

The cosmologist took a deep breath. "No. We won't experience prolonged weightlessness till midpoint in

our journey. Then we'll have about six hours of it while the captain turns the ship around and realigns it

precisely. We'll be coasting at our top speed then, and our six hours will be more like six months for the

folks back home—we'll travel half a light-year in that time."

"I see," said the passenger, more confused than ever.

"But we don't have to worry about all that right now," the officer said with heavy professional patience.

"I'm going to start with a little history."

He moved to one side of the large holo frame that had been set up on the stage and looked around the

small theater to assess the comprehension level of his audience. There were about two hundred of them,

mostly Martians and other Solarians. The Al-pha Centaurans who were returning home, of course, would

have been exposed to orientation lectures on their way out and would consider themselves seasoned star

travelers.

Hamid-Jones took the opportunity to study his fellow voyag-ers, too. He saw rows of earnest expressions,

the faces of people determined to squeeze the last drop of significance out of this— for

most—once-in-a-lifetime journey.

The cosmologist, on the other hand, might have made the crossing six or eight times, despite his apparent

youth. Each round-trip would assess him only four years of his lifespan, while stay-at-homes aged a dozen

years.

It was an arresting thought to Hamid-Jones: that fresh-faced youngster had probably been born before

most of the graybeards in the audience. It brought home the magnitude of the journey. The people around

him would be his neighbors for the next two years. And when he finally disembarked at Alpha Centauri, he

would be separated from everything and everyone he had ever known by a gulf of time. Lalla would be a

woman of mature years, older than he, before he could return to her; Aziz, if he were still alive, would be

declining toward middle age.

"The key to feasible travel between the stars was discovered in the eighteenth century of Islam—the

twenty-fourth century for those of you in the audience who are Christians."

The cosmology officer made sure he had their attention before going on. "Until that time, launching an

interstellar vessel of any sort was a ruinous and impractical enterprise that even a rich society could afford

only once or twice in a generation. Here's what some of those primitive starships looked like."

The holo frame flickered into life and began to show a pro-cession of improbable shapes. There were

great scepterlike ob-jects with bulbous ends, their scale impossible to guess. Collections of checkered

spheres in frameworks. Flatirons at the ends of poles. Double-ended umbrellas turned inside out. A thing

like a dandelion gone to seed. Even something that looked like a child's kite.

"These early efforts divide basically into three groups. Ships that carry their own fuel. Ships that collect

their fuel on the way. And light sails and other schemes for getting a free kick from something that remains

in the Solar system, like mass drivers."

The audience gaped at the collection of antiques. Hamid-Jones heard a few oohs and ahhs. There was

something impres-sive about those brave, ungainly shapes. They showed the indomitable spirit of man.

"Let's take the fueled ships first. They came in many styles. Ion drives. Various fusion

reactions—deuterium-deuterium, deuterium-tritium, deuterium-helium three. There was an inter-esting

fission engine using a boron 11 to helium reaction that needed a hydrogen fusion reaction to trigger it, but

that provided a better push than any of the merely fusion drives. And would you believe that there were

actually plans for one early star drive that depended on the explosions of nuclear bombs—one every few

seconds—to kick the ship along?"

He gave the audience a look at the ship—a bundle of cylinders with something that looked like a snowball

at one end and a goblet of steel at the other.

A hand popped up in the third row, and the lecturer said, "Yes?"

"Excuse me," came a hesitant voice, "but you didn't men-tion any kind of antimatter drives."

"You're getting ahead of the story, but yes, there were crude beginnings in that direction, too. They knew

how to make antimatter as a laboratory trick—not too practical for producing antimatter in industrial

quantities. An antimatter factory was actually built out past the orbit of Neptune. A Triton-Swiss

en-terprise, I believe. The accelerator rings were about fifty miles in diameter, stacked in a cylinder a

couple of hundred miles long. It was able to produce about a gram of antimatter per day."

After a pause to let that sink in, the cosmology officer allowed the ghost of a smug smile to steal over his

face. "Pity. Because gram for gram, an annihilation reaction produces about one hun-dred forty times the

energy of, say, hydrogen-helium fusion. Even so, they'd have been lugging along moonlet-size tanks of

hydrogen and antihydrogen—the antihydrogen being stored in some kind of gigantic magnetic flask with its

own ticklish en-gineering problems. And then, a ship the size of the Saladin would have to carry seven

times its weight in fuel to reach sixty percent of the speed of light. The time-dilation effect would be

negligible—about one point two four. A trip to Alpha Centauri would take five years of our lives instead of

two. Perhaps civi-lization could manage. But a trip to, say, Delta Pavonis would cost us about thirty-three

years of lifetime instead of, essentially, the same two years. Impossible! And to get up to ninety-nine

percent of the speed of light with a time-dilation effect of seven to one—still not as well as we do in

modern times—a ship like the Saladin would have to carry forty thousand times its mass in matter and

antimatter. So we see that the annihilation drive by itself is not the answer."

He began to pace a little. "The problem with all star drives that carry their own fuel is the same: the great

satan called mass ratio. The faster you want to go, the more reaction mass you must carry—and all that

additional reaction mass itself must be accelerated, at ever-increasing energy cost. For example, that ship

whose picture I showed you would have to carry one hun-dred fifty times its weight in nuclear bombs in

order to travel ten light-years in one hundred fifty years. To shorten the trip to eighty years, it would have to

carry twenty-two thousand times its own weight. And then it would have traveled only as far as Epsilon

Eridani."

He fiddled with his holo wand and produced tables of figures to which no one paid attention.

"So the ships that settled the nearer stars were slow boats, traveling at five or at most ten percent of the

speed of light. The first load of colonies to Alpha Centauri took ninety years to reach there, and when they

landed, they found the children of the second colony ship waiting there to greet them. Some of the

generation ships are still undoubtedly out there in the void. We can only wish their inhabitants well and hope

for a safe planetfall for their descendants."

Hamid-Jones's attention strayed to one of the rows in the next aisle. Out of the corner of his eye he

thought he had seen some-one there twist a head to look in his direction, then look quickly away again. But

when he turned to see, there was no one to meet his gaze—just a row of earnest profiles engrossed in the

lecture. One of the profiles was obscured by a fringed headcloth as the man slouched forward in his seat to

get a better view of the stage. There was nothing to distinguish him; by his headdress and natty robes, he

looked like any Martian prosperous enough to afford passage on the Saladin.

Hamid-Jones remembered the attaché's warning about Assas-sins and covert government hit men and

decided he was being morbid. So what if someone had glanced at him? Other passen-gers, their attention

wandering, were also sneaking looks at their fellow voyagers; he was doing it himself.

He returned his attention to the lecture.

"So much for ships that carry their own fuel. But what about ships that scoop up their fuel on the way?

Fuel that then has only to accelerate the payload and not itself?"

The holo frame showed a tremendous web floating in space. It was insubstantial enough for stars to shine

through it. The holographic window rushed toward it at dizzying speed until it finally zoomed in on a tiny

mite at the center of the web. There was another adjustment of scale, and the mite became an enor-mous

vehicle, a double-ended cone assembly bristling with many spokes. One could see that the machine was

spinning its own web with a thimblelike hub that was rotating like a whirligig.

"This is something called a Bussard ramjet. The theory was that it would scoop up hydrogen atoms in

interstellar space, squeeze them in a magnetic field, and initiate a fusion reaction whose efficiency would

increase as the ship went faster. The hydrogen not used in the fusion reaction would be shot out the rear as

reaction mass. There was no theoretical limit to the speed such a ship could attain, and velocities in excess

of ninety-nine percent of the speed of light were thought possible, giving the Bussard ramjet a relativistic

advantage over ships that had to carry their own fuel, and making possible the same sort of in-terstellar

commerce we enjoy today."

He shook his head sadly. "But this promising vehicle finally foundered on engineering difficulties.

Hydrogen is thin in or-dinary interstellar space—on the order of one atom per cubic centimeter. Magnetic

scoops thousands of miles in diameter would be required. To keep such a scoop extended, it would have to

spin round its hub, and if the spin failed it would collapse and destroy itself. Then there was the problem of

the mass of the scoop itself. A very modest thousand-ton vehicle would need a scoop the diameter of

Earth's moon, with a collecting area of about four million square miles. Translated into something even as

insubstantial as a one-mil superconducting fabric, that would add up to over two hundred million

tons—twenty thousand times the mass of the spacecraft itself. You're back to the same kind of mass ratios

as when you tote tanks of hydrogen."

The child's kite appeared again in the holo window and re-solved itself into an immense hexagonal figure

braced by struts and stays. A flealike reentry vehicle gave it scale. The kite disappeared, was replaced by a

radiating burr with a tiny pod at the center. The burr, in turn, gave way to something like a shiny parachute

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AGATHERINGOFSTARSBookTwoofTheMechanicalSkyDonaldMoffittCopyright©1989byDonaldMoffittLibraryofCongressCatalogCardNumber:89-91891ISBN0-34.5-36574-7CoverArtbyDonDixone-bookver.1.0GratefulacknowledgmentismadetoArthurC.Clarkeandhisagents,ScottMeredithLiteraryAgency,Inc.,8453rdAvenue,NewYork,NY10022,forpe...

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