Wheelers

by Ian Stewart

  The cloud layer is about forty miles thick, with winds that typically average more than two hundred miles per hour at the equator. The temperature rises rapidly, so that at the bottom of the layer it is close to that of Antarctic ice fields on a summer's day. The pressure there is much the same as it is on the Earth at ground level. In neighboring bands of cloud, the winds blow in opposite directions, relative to the atmosphere's mean rotation; high-speed jets of Jovian air mark the boundaries of the bands. The deeper regions are hotter still, but the pressure also rises dramatically with depth, so that below the cloud layer the gas giant's "atmosphere" soon becomes liquid. Like Earth, Jupiter is an ocean planet. Unlike Earth, its oceans merge almost smoothly into its air, and both are made from hydrogen and helium, mixed with small amounts of methane, ethane, ammonia, acetylene, and other gases.

  What all this meant to the vacuum-balloons' designers is straightforward. Pressure is not a problem, even if you want to go below the clouds into the unknown layers that lurk beneath. Temperature is not a problem, as long as you design for intense cold. The greatest problem is wind—not the winds that forever encircle the giant globe, but the local gusts, up to five times as fast, that spin off as swirling vortices. A balloon, however, can readily sail with the wind if it is kept away from extremes. The turbulent "wake" of the Great Red Spot is definitely something to avoid, and the easy way to do that is to stay north of the equator. So Skylark dropped its probe neatly above the relative calm of the North Temperate Zone, dipping its technological toe into the Jovian sea to find out whether anything wanted to bite it.

  The probe got as far as the cloud tops, and there its descent was temporarily halted while the team digested the data acquired so far, paying particular attention to the gadgetry that monitored the stresses in the balloon and the suspended gondola. All seemed well, and the decision was taken to deploy three more balloons, all above the cloud layer and in different atmospheric zones—North Equatorial Belt, North Temperate Belt, North North Temperate Zone.

  Already, the biochemical sensors and analyzers had found ample signs of Jovian life. There were complex organic molecules in abundance, curious quasi-bacterial organisms, the occasional strand of floating pseudoalgae . . . there were no words for what they were seeing, so they took refuge in terrestrial terminology and vague Latin prefixes. Their reports caused a stir back on Earth—the first alien life! But the stir was muted by a feeling of anticlimax—the task force wasn't looking for bacteria and primitive plants, it was looking for intelligence. The big masses of gas-sacs, discovered soon after, looked promising—for a time—but it quickly became apparent that they had no more intelligence than the seaweed they resembled. Still, Jupiter's surface area was truly gigantic, and its atmosphere was deep beyond human experience. Patience was the watchword. There was plenty to study, a whole new world of exobiology was opening up . . . Time slid by, and reports rolled in by the thousands. The scientific justification for the expedition was undeniable. Unfortunately, that wasn't an important issue, though in the flurry of excitement it was easy not to notice. To most people, the comet still seemed comfortably far away: with roughly a year and a half to go, the task force would surely succeed in stopping it. Others, though, were beginning to fret, and, Sir Charles was coming under mounting pressure from Uhlirach-Bengtsen—which was largely counterproductive. It was leading to a crisis of confidence, not helped by things like the allegedly humorous item he'd found in his Xmail one day, downloaded from the Tyrannosaurus Wrecks Xsite:

  1 yard 10 years germicide

  10 yards 25 years insecticide

  30 yards 50 years homicide

  100 yards 100 years countrycide

  1,000 yards 100,000 years genocide

  10,000 yards 30,000,000 years tyrannicide

  100,000 yards 1,000,000,000 years distinctlyonthebigcide

  Perhaps because of his growing lack of confidence. Sir Charles was becoming even more cautious than before, and this affected his strategy for deploying the probes. From a distance, Jupiter's cloud layer seemed impenetrable, but that was an illusion resulting from a viewpoint that tried to look down through hundreds of superimposed sheets of cloud. There were gaps and holes everywhere, changing positions erratically as the winds carried the clouds at different speeds in different layers. Light bounced down through these gaps, penetrating to a surprising depth. Some regions would be briefly ht by broad shafts of sunlight when several gaps temporarily lined up, but between the clouds the light was mostly diffuse, dimming to twilight and then total darkness as it filtered into the depths. Because the cloud cover was unpredictable. Sir Charles was understandably reluctant to fly his balloons blind. For several months, therefore, he refused to permit them to be sent below the cloud tops.

  Having arrived at Callisto, Prudence was no longer sure that it would be a good idea to make a beeline for the buried wheelers. Their luck had been bad: by chance the task force had stationed several probes in very awkward places, making it far more difficult to get near the burial site than she'd hoped. And increasingly the approaching comet gnawed at her mind. The interminable trip out to Jupiter had given her time to think, and her motives had started to seem shameful. Maybe Charity had been right after all. She might have been able to ignore these thoughts, and go wheeler hunting with a clear conscience, if the task force had been making real progress. But the more she looked into what it was doing, the unhappier she became. The wheelers would have to take a backseat for a while: Earth's vital interests were not being well served.

  "The problem with Charles," said Prudence, "is that he's enormously efficient and enormously ineffective. He hardly ever stops working, but it's nearly all routine stuff. . . I'm sure he thinks he's making tremendous progress, but mostly he's chasing his own tail. He puts up an effective smokescreen, though: you have to have your brain seriously in gear to realize that he's not actually getting anywhere. Me, I'm different, more intuitive. See things in context, leap to conclusions . . . From the first day I was assigned as his student—long ago, I'll tell you all about it sometime—anyway, right from the start it was obvious to me that he lacked any real originality. No flair, no instinct—but man, was he a slave-driver! Drove himself more than anyone, too. And he was an absolute stickler for scientific protocol— sound experimental design, very thorough analysis of every possible way for measurements to go wrong ... He taught me a lot when it came to technique, he was the most thorough person I've ever met. He just . . . had no sense of the bigger picture."

  She was finding it increasingly difficult not to get involved in the task force's work. Her original plan—get in quick, grab as many wheelers from their icy tomb as Tiglath-Pileser could carry—was firmly on the back burner. From out here, with the homeworld a distant speck of light, it seemed petty. She should have known, space always had that effect on her. What was the point of digging up a few more wheelers if Charles screwed up? And the more she watched him in operation, the more firmly she became convinced that this was exactly what would happen.

  "Jonas, didn't I say that the aliens had to be on Jupiter itself—way back, before we even left Earth?"

  "You did," Jonas agreed. "Mind you, at various times you also said that they were probably in pressurized installations beneath the ice of Ganymede, and in orbit on huge generation starships."

  Prudence grimaced. "Yeah, well, can't get everything right. But I did have Jupiter a lot higher on the list than those awful, barren moons that that fool Charlie Dunsmoore's wasted years running through a fine sieve!"

  "Absolutely," said Jonas. "We all agreed on that. But we didn't have the slightest evidence to back that theory. Charlie-boy has to rely on advice from experts, and we all know what they told him. He just did what he was instructed to do."

  "Precisely my point," said Prudence though clenched teeth. "And fair enough, to begin with. The problem is that he failed to cut his losses when it first became likely that the aliens weren't where the experts expected them to be. He should have done a few things th
at he wasn't instructed to do. Damn it, he's the boss, right?"

  "He has to carry an awful weight of responsibility," said Cashew. "I've seen network execs in the same kind of position, and most of them stick to their brief. If you use your initiative and anything goes wrong, you can't cover your back. Stick to the book: no worries!"

  "And if it goes right," added Bailey, "someone higher up grabs the credit."

  Prudence acknowledged their points with a wave of her hand. "Sure, sure. But Charles doesn't have a back to cover. If he uses his initiative and it doesn't work out, all that happens is the critics get blown to smithereens!"

  Jonas finally realized that Prudence was leading up to something. She seemed unusually diffident, and it took several minutes for him to persuade her to say what was on her mind.

  "Jonas, I've spent much of my life trying to stay well clear of Charlie Dunsmoore. I absolutely don't want to help pluck his irons out of the fire. But there's a frail, beautiful world back there, and if I don't do something soon, it's going to get smeared all over the face of creation. I think we're going to have to bail Charlie out."

  Jonas looked worried. "But Pru, he'll never cooperate with us! There's been far too much dirty water under the bridge—"

  "I know. In a way, it helps. At least I won't have to work with him. But I am going to have to do his work/or him." She balled her hands into fists. "Damn his eyes . . . Jonas, check me out on this, okay?"

  "Okay"

  "One: we know the aliens are on Jupiter."

  "Check."

  "Two: Charlie hasn't found hide, hair, nor reptilian scale of them above the cloud layer. Lots of primitive life, yes—some big . . . rafts of organic bubbles, that kind of thing . . . but nothing intelligent."

  "Check."

  "Three: ergo, they aren't there. They're down in the clouds where it's hard to see anything. Got to be."

  "Check. That's where I'd be if I was an alien."

  "If they're down in the liquid ocean, we're dead. No hope of making contact."

  "Check."

  "But—I just don't believe they are. The cloud layer is much more likely."

  "Hmmm. Not sure of that one."

  "Me neither. Hope over reason, maybe. But we don't lose anything by making that assumption."

  "Check."

  "Unfortunately, Charlie isn't keen to send valuable balloon probes down where there's no visibility. Even with heavy searchlights, state-of-the-art sonar, and all-around radar. He's scared he'll lose one."

  "Check."

  "Which is where you come in."

  "Che— What?"

  Prudence told him.

  Montgolfier —balloon probe 2—was mapping the distribution of germanium tetrahydride at different levels in the North North Temperate Zone of Jupiter's lower troposphere. There was reason to believe that the levels of this rare gas correlated in some manner with the occurrence, miles below, of the "white ovals" that had puzzled astronomers for centuries. It was slow, careful work, for the exotic gas was present in concentrations of one ten millionth of a percent. So far, the evidence for a significant correlation had been decidedly tentative, so Sir Charles had authorized a further week's observations. Ostensibly this was because there was germanium in wheelers, so germanium tetrahydride might be a sign of wheeler manufacture. A positive correlation might indicate that it would be worth taking a close look at the white ovals at some future date.

  The probe hovered less than a mile above the cloud layer— the lowest that Sir Charles had yet dared to authorize. It zigzagged slowly to and fro on its attitude thrusters, sampling the external gases and transmitting telemetric data back to Europa Base by way of the newly installed network of jovicentric comsats.

  Back at Europa Base, everything seemed routine, and Keith Chow, senior technician, decided to take a quick break for a bulb of coffee and a protein bar. He wasn't exactly forbidden to leave his post, but it wasn't exactly permitted, either. However, they all did it, because the scheduled workload left no room for substitute controllers, even if only for a few minutes.

  When he left for the kitchen area, the probe was functioning normally. When he got back and cast his eye over the diagnostics window, he caught his breath. The numbers didn't look right. Two data streams in particular gave cause for concern—altitude and internal gas pressure.

  He called over to a second controller at a neighboring console, whose nominal task was working with probe 3. "Zirphie, if I slave you some data can you spare a moment to check it out for me? I think we've got a problem with probe two." Zirphie nodded: it would help relieve the boredom.

  After a few moments, she spotted the bad readouts. "Okay, Keith, I see what you mean. I'd say you've got a slow leak in the buoyancy shell. Air's getting in."

  That's what he'd thought, too. "I'm going to give the shell a squirt of sealant and flush the air out again. Can you back me up on that decision? Halberstam will chew me out if he decides I goofed." All the controllers knew that they had to play the game by the rulebook—there was very little room for on-the-hoof improvisation. And Wally Halberstam was ultraconservative—administratively and politically Superficially, he seemed a bumbling oaf, but he could make your life exceedingly miserable if he didn't like your attitude. Mission-critical decisions had to be verified independently. Zirphie would have been happier if Keith hadn't chosen to ask her, but the responsibility went with the territory and anyway this was straight out of the guidelines. "I concur—if you don't do something soon we could lose the probe. Logging my support for the decision now . . . Okay, done. She's all yours!"

  Keith waited until his own console displayed her acceptance, and then instructed the probe to emit a short burst of gaseous sealant from a reservoir attached to the inside of its vacuum flotation chamber. The contingency had been planned for.

  What happened next, hadn't. The pressure indicator suddenly leaped above zero, and the altimeter began to drop like a stone.

  "Hey—what the hell did that do?" The probe was starting to topple gondola-up. Chow tried to right it, but nothing seemed to be working.

  "The reservoir exploded," said Zirphie calmly. "The release valve must have been faulty Look at those readings for sealant reserve levels."

  "Negative? But we can't have less sealant than zero—right, you got it, the sensor must have been damaged when the reservoir blew up. And judging by the change in attitude, gas is flowing into the flotation chamber through a hole where the reservoir ought to be."

  "Looks that way. I'll ask the computer for verification."

  "Okay. While you're doing that, let's see what the 'scope shows on visual . . . hmm, the image is faint and shimmery, but she's sure as hell dropping ..." By now Keith looked distinctly apprehensive. "Had to happen on my shift, of course . . . Zirphie, I didn't do anything wrong, did I?"

  "Can't think of anything. You did check that the valve was up to operating temperature?"

  "Yes, of course." Did I? Shit, maybe I didn't! I cant remember . . . where's the damn log file? Relief flooded through him. I did, praise the saints. Someone in the prep team must have screwed up . . .

  In the telescope image, the tiny dot of the probe was suddenly swallowed up by cloud. "The Old Man isn't going to like this, we're losing her. Any chance we can go to visual?" He tried. "No, nothing, the cameras must have been ripped off. She's starting to break up!"

  Words failed him; this was terrible. What if it was poor design? They could lose all four. It was a mess now—it could easily become a big mess. A mess with his name written all over it in indelible ink. He could only hope that he really had covered his back. The inquiry board would turn over every stone until something crawled out, and it was perfectly capable of finding something nasty even if the stone was as clean as a whistle. After all, the board would have its own back to protect, and that back was a lot broader than his.

  Bright Halfholder of the Violent Foam awoke from her shallow torpor and sniffed the air with nervous anticipation.

  It was time.
Time to strike a blow against the Elders' unthinking destruction of the lesser worlds—destruction born of needless fears, withered lifesouls, and mindless adherence to the mundane and the ephemeral.

  The rubbery walls of the blisterpond became confining instead of comforting, a sure sign that her mind was returning to full awareness as it emerged from a light level of estivation. The rippling of Halfholder's leathery hide sent wild shivers spiraling along her neural core as the excitement built. In an effort to remain calm, she worked though her checklist, deliberately confirming each item twice, making sure that her beltbag contained all the vital equipment prescribed by her advisers . . .

  The Carrier was sealed in a pouch, for safety

  She brought her prompter up to her eyes, and the shivers became unbearable. Yes, it is time. She could scarcely believe that the long wait was over.

  A brief squirt of release hormone peeled back the blister-pond's roof like an eyelid surprised by morning, and Halfholder floated cautiously upward, until her ring of eight oval eyes cleared the sunken rim.

  She spun gently in an i-spy

  As she had expected, the streets here, within sight of the Edge, were devoid of fellow blimps. No guardians, then. To one side the city's barrier fringemass swayed ominously, a deadly, moving forest. Wisps of floating plant life drifted past, then denser bunches, some possibly hiding predators. She bobbed back into the blisterpond, alarmed by a shoal of porca that swept past in line astern, bumping into each other and wallowing awkwardly in the vortices shed by the city's trailing edges. Foolish to react to such timid creatures . . . even more foolish not to.

  Soon Halfholder would have to negotiate those vortices, thread the dangers of the fringemass, and brave the freedom of the winds. She would deploy the specially offcast Carrier that she kept for safety in a reinforced pouch, bringing horror to her Elders and honor to her cause. Her gas-sacs tightened in anxiety To relax them, she reached into the pouch and brought out the Carrier, reveling in the feel of its rough metallic surfaces, passing it from tentacle to tentacle to bring its nodule-covered shell within range of her sharpest eye. Pride flared in her breathing tubes—the tiny semi-living machine had been a valid construct, the most valid yet of any of her offcasts.