by John Barnes
After a few more kisses, she led him quietly to an unused, dark utility space, and whispered that she wanted to "try the whole thing."
When they had finished with Phrysaba's introduction to the whole thing, and both were feeling comfortable and happy, Jak said, "I suppose I should feel guilty about Sesh, but it's not easy to; I probably won't even get to see her again, probably not ever. And they have to keep her physically comfortable, no matter what the idiots on the viv and the vid are saying."
Phrysaba rolled against him, her small firm breasts pressing on his chest, and gave him a long deep kiss. "There. That may help you forget."
"Well, you don't have the skill level yet—"
They practiced some more, but weren't quite inclined to continue again; he was a little tired, she was a little sore, and both just enjoyed the contact with each other too much to want to interrupt it.
"So," she said, "since tomorrow afternoon is when the ship starts prepping for the cargo switch at Mercury, we probably won't have another time like this till after that—probably a couple of days afterward, allowing for recovery time. I have a feeling that this is best when you're well rested and in a good mood."
"Your feeling is singing-on. Everyone seems to be either anticipating or dreading the cargo switch—why? I mean, if it's so awful, why do ships do it, or if it's such a great thing, why all the bitching?"
She sighed. "About a week from now you won't have to ask at all; you'll dak it as well as you dak anything. The great thing and the terrible thing about the cargo switch at Mercury is that it's a short time of unbelievably intense work and the whole future of the ship rides on it. I had a literature teacher who said it's kind of Like how groundside farmers used to feel about harvest, or retailers feel about Christmas—either it works or it doesn't, and if it doesn't, you're scrogged. Mercury is the thing that keeps most of the sunclippers flying and making what little profit we do; they're really the heavy-metals industrial center of the solar system, so they need everything biological, informational, pretty much anything you don't make out of metal, and they export stuff that everyone else needs—pretty much everything you make out of metal.
"Plus they're located way down the solar gravity well but also where there's the most sunlight and solar wind to catch in the sails and scoops. So no matter what you picked up in the upper system, if you can just drop in for a fast swing around Mercury, you can sell the whole cargo and get a whole new one that will be in demand, and usually pick up enough momentum to have a fast, straight shot to your next destination. That's why there's the old saying among crewies that 'There's always gold in Mercury.'
"But on the other side of things—well, first of all, unloading almost all of the cargo and replacing it with another cargo is quite a job. The stuff comes aboard in mixed lot containers and then goes into containers routed to everywhere on Mercury, so we have to get it from all its various storage places, repack it for Mercury, loop launch it, get it onto Mercury's loop—which means that everyone who can fly a longshore capsule gets to play a frantic game of tag in space for hours— and fit all that into the window of a brief pass at the planet.
"And then, too, it's dangerous. That much cargo handling always is, and the sails are more dangerous when there's a loop deployed, and around Mercury you're always coping with substorms."
"What's a substorm?"
"Mercury has a pretty strong magnetic field for its size—not like Earth or Jupiter, but plenty more than most other planets—and particles from solar storms get trapped and sometimes pile up in one place or another, so that you get these very intense local events, which can make the sails do weird things because part of how they're controlled is by manipulating electrostatic charge on them, and they can suddenly pick up a charge ten or twenty times what we use to control them, just at random.
"Coming into the Jovian system or the Earth system it's no big problem, because those planets are big enough and their fields are strong enough so that usually when you're dealing with a substorm, you're fairly far out in space, with lots of time to recover. Mercury's field is weaker, and Mercury is airless and small, so you can lit-erally have substorms touch down on the surface—that's why they have so many deep shelters all over the planet. So you can be just a few thousand kilometers away from the surface, with a million square kilometers of sail spread, a short distance from Mercury's launch loop and with your own loop deployed, when all of a sudden the sails start buckling, or waving, or collapsing, or pushing apart from each other. It scares the hell out of everyone, and rightly so.
"And that," she said, "is everything I know about why we all hate Mercury and love Mercury. Because we have to go there to keep going, financially (we'd never make it financially if we didn't), and because once we do it's miserable hard dangerous work. How do you feel about rescuing this princess of yours?"
"I guess it's kind of the same," Jak said. "I have to, but I'm scared, but I really want to… Well, shall I take you back to your quarters, or do you want to work on forgetting all about it for a while longer?" He stroked the inside of her thigh, letting his fingertips just reach onto her buttocks.
"Hmmm. Forget the cargo switch, or forget the princess?"
"Bet if we try we can forget both," Jak said, and kissed her deeply, again.
When he finally got to his bunk, before he drifted off to sleep, Jak thought about how quickly everything with Phrysaba had happened, but still it seemed very much in character from what he had learned of crewie ways. The spaceborn are not sentimental. They tend to make a firm, considered decision, one way or another, and then implement it with complete commitment. The djeste of it all specked to Jak, when he thought about it. People who spend much of their lives making close passes at objects moving at orbital speeds, and are forever making irrevocable decisions that will determine what happens to them many months hence, are people who act more than they worry. It was another reason to think he might want to stay in this world—after he rescued Sesh, of course. Everything came after that.
Jak had gone to bed early enough to make sure of getting an extra hour of sleep, because everyone had warned him about how exhausting cargo switch would be.
It took about eighteen hours to spin up the loop. Thus they always started the loop when they were a bit more than twenty-four hours from transfer time, so that they had a generous allowance of extra time and so that the most likely problems would still leave them time for another try. Ideally there would be eighteen hours of spinning the loop up and shifting freight in the hold into containers to be taken over; an hour and a half to fly all the containers to the Mercurial loop; an hour and a half to fly back the new containers; and then three hours of moving containers and catching and re-storing the longshore capsules. If anything went wrong, it could be much longer. A few "lucky" workers—and Jak had volunteered to be one of them—would be working at top speed for very nearly the whole time.
Because rotation made everything more difficult, for the last day and a half before the cargo switch, the concentric rotating rings of the ship were very gradually braked to a halt, until finally the only remaining gravity was the fraction of one percent of a g from the solar-sail acceleration. When Jak awoke, he found a pen and a pair of earrings, which he had left on the little extensible night table, bouncing slowly around the room. He checked to make sure nothing else had wandered, caught his belongings, stowed them, and folded his bed. He pulled on his crew coverall and swam through the now all-but-gravityless corridors toward the central area where removable walls had been pulled to form a giant commons.
The sound of the big early breakfast was loud and sharp, with the nervousness of those who had done the planning, the boisterousness of those who would be working hard and long, and most of all the awareness that today they would be doing something unusual. Jak filled up quickly on the squeeze bottles of coffee and the pastries filled with textured protein; the stuff had been engineered to get more than a day's worth of calories into everyone quickly, without stuffing their sto
machs, and as far as Jak could tell from the heavy acid feeling in his gut, it was working.
His first assignment was in the holds; nearly all the boxed cargo in the hold would be getting off at this stop, and it had to go into the big cargo containers in a particular order. As he moved each container into place and locked it down, its sides glowed with the numbers of the containers that must be parked next to it—get it wrong and a warning bell sounded, not to mention the supervisor glaring in a very disturbing way. Only the smallest children got it wrong, and even they learned quickly because their friends and older sibs made fun of them when they made mistakes. Of course, autodol-lies did most of the moving and large parts of the lift-ing, but human hands and eyes were still the quickest, and the ability to look into a cargo container a hundred meters long by twenty square and see dozens of numbers, then recall where they might be, was surprisingly important even when the machines were keeping accurate track of the location of most of the cargo most of the time. It takes a human eye, attached to a human body that might get some extra rest if things work out, to guess ahead and cause the sort of result commonly called luck.
All the while, Jak was walking back and forth beside autodollies, or carrying a box around a corner or through an opening too small for the autodolly, or helping to carry boxes because the autodollies were all in use and this could speed up the loading process, or rechecking what an autodolly thought it should do next and changing that to something better.
After six hours, with only a minute or two now and then for a drink of water or a quick piss, Jak was beginning to see why Piaro had thought he ought to be warned about what this would be like. He was tired and sore, and he'd bumped himself now and then just often enough so that a part of him was already looking forward to the big party in the Public Baths that traditionally followed cargo switch. Furthermore, though he and the many others had already loaded an impressive number of containers, the pile of containers waiting to be activated and opened was still at least two-thirds of what it had been when they had started, and the vast stack of loaded containers did not look nearly as impressive as the many, many rows and heaps of yet-to-be-packed cargo.
Then Lewo came by and tagged him on the shoulder.
"Old pizo, union promotion rules say I need to add a few untrained workers for the spin-up crew, and you're thoroughly untrained—I should know, I failed to train you myself. Report to the loop room in twenty minutes. On your way there, hit a bathroom and wash up, then hit a canteen and get at least two sandwiches and two cups of coffee in you. You're overworking and underresting."
Jak managed to exceed orders by one sandwich and two cups of coffee and still get to the loop room a minute early. Where the cargo packing had been a matter of adding human judgment to large-muscle activity, the loop room was a place that relied on the human brain's ability to multitask and to absorb and interpret large amounts of information quickly. Uncle Sib had always said that every task at which humans excelled machines made use of some ability that had been useful back in the caves. Rethinking cargo packing on the fly was using the same parts of the brain that had evolved to make decisions when a hunted animal didn't do what it was supposed to. What he was doing in the loop room was using the part of the brain that, fifty thousand years before, had been good for hitting a bird with a thrown stone.
A loop is a closed ribbon of superstrong superconductor, moving at very high speeds, yanked through a superconducting magnetic coil like a plunger through a solenoid and kept open by its own centrifugal force, so that it forms a giant circle. When fully deployed it is tens or hundreds of kilometers across and moves at several kilometers per second; any craft with a variable magnetic drag linducer can be accelerated up to the speed of the loop, and if it has the power reserves to run the lin-ducer for forward propulsion it can even accelerate beyond loop speed, so that the amount of fuel a shuttle or package must carry is drastically reduced.
Outgoing cargo carries a small fraction of the loop's energy away with it; incoming cargo adds energy to the loop. When the loop is braked and coiled for storage, almost all of the energy is recovered into the brakes, so very little energy is wasted, and in fact if a ship or station happens to be receiving more than it is sending, very often it ends up with a net energy gain (for which, of course, it is expected to pay).
Phrysaba had explained that to Jak; since they were dropping off an unusually large and heavy lot of cargo at Mercury, they would be deliberately coming in on a trajectory that would require the highest delta-v permissible, to produce an exaggerated net energy difference and thus slightly increase profits. This meant having the biggest possible loop at the highest possible velocity; it made the Spirit of Singing Port harder to handle, but they had done this many times before, and it had always worked out.
On an immense station like the Hive, almost as big as Earth's moon, where spaceships of all kinds come and go constantly, a loop is simply left up and running, but because of its enormous angular momentum, a loop is also a very effective gyroscope, and on a sunclipper, which must move and maneuver, having a loop running for more than two or three days is a major nuisance. Thus when approaching a big station, an asteroid, or an airless world that has a loop up and running, a sunclipper deploys its loop as late as possible before closest ap-proach, aiming to have loop speeds and directions at the outer edges match as nearly as possible during a critical period of no more than about five hours, and then furls its loop as soon as possible after cargo and passengers are transferred. While the loop is deployed, the ship is almost unmaneuverable, locked into its course until it can recover the energy from the loop.
Deploying a loop is like spinning up a lariat big enough to lasso New Jersey, fast enough to orbit the Earth, while running it through a croquet wicket. Many thousands of parallel processors run faster-than-realtime simulations to decide when to attach another piece and when to cut it open to expand the loop. But although machines have superb reflexes, they are not noted for their perception. Machines can calculate what is about to happen, and calculate what will happen if you change something, and they can draw it on the screen, but they cannot tell a harmless wobble from a disastrous snarl nearly as well as a human being.
So the job Jak and his many co-workers were doing was to supply judgment for the massively parallel processor system that ran the loop. He had a scale from red to green, with yellow between, and a movable pointer, on his screen; the machine showed him possibilities a few seconds into the future, and he marked them as anything from harmless to disastrous on that scale. Each evaluator saw a dozen possibilities per minute or so; every possibility was evaluated by three different evaluators, and only those which received three full greens were considered for actual implementation. The result was that with 250 evaluators working, the system could consider about a thousand possibilities per minute, which gave it an effective accurate reaction time many times that of a human being, and yet with an almost human level of judgment.
The most dangerous period was the middle period of the spin-up. When the loop was still small, just a kilometer or two across, it had relatively little momentum and any accidental waves or wobbles could be fixed by drawing energy back; when it was all the way out to sixty kilometers across, it had so much momentum that the last increments of loop material and kinetic energy could make relatively little difference. But between about five kilometers' diameter and about thirty, it was still possible to jolt the loop enough to make it misbehave from mere normal increments of energy and material, and it was no longer possible to trust that the available forces would suffice to keep it controlled and out of various forms of dangerous behavior—sinusoidal waves that could cause it to brush the coil with explosively disastrous results, twists that could make it begin to fold in with equally catastrophic potential, and so forth. Thus, where a small number of technicians sufficed at the start and the finish, the middle required everyone who could be taught to recognize the basic pattern of trouble and move the slider quickly enough.
&nbs
p; Outside the loop whirled at about five kilometers per second; at the end of the coil, new pieces were fed on, each ten meters or so long, folded so that both ends were attached to a welding clip. The clip grabbed the loop and welded both ends of the new piece to it, just a half centimeter apart, then snipped the loop between the two new attachment points, fast enough for the new, welded-in length to clear the entrance to the coil about a second later, as the loop came back around. Second by second, dekameter by dekameter, the loop grew and circularized into space on the sunside of the sunclipper, a mere kilometer from the thousands of monosil lines that could cut it instantly. Making the whole job harder, the angular momentum of the loop locked and held the ship in a single orientation that constantly threatened to collapse the sails, so that the sailing crew was triple its usual number and working like mad; fusions were constant, and riggers were out cutting and splicing all the time, as well. The whole process, from the three mainsails each twice the size of Africa to the city-sized habitat to the immense racing loop behind it, stretched across six thousand kilometers of a sky, a barely controlled disaster that was always less than a second from going out of control.
A distant corner of Jak's mind was grateful to be as busy as he was with the screens and images; if he had thought about what was happening, he might have frozen in sheer terror.
When Jak's relief tagged him and sent him to the foot of the relief line, the process of swimming out of his chair disoriented Jak.
He gratefully gulped the icewater and more coffee that the kids serving the line brought to him, swallowed the nutrition supplement they handed him, and washed it down with yet one more round of coffee and icewater. He breathed, stretched, and focused as the line of other workers taking a break moved ahead of him. Everyone around him was also stretching, yawning, trying to work out the kinks. The line snaked into a rest room and Jak got a welcome moment's relief.
