21

JUPITER SWINGBY

The outer regions of the solar system are remarkably empty. It is certainly possible to run into another object, particularly when flying through the Asteroid belt, but you have to be freakishly unlucky to do so. And if that other object happens to be a ship, with its own navigational control system, then the chance of collision contains such a string of zeroes after the decimal point that no rational person should worry about it.

Humans are not, of course, particularly rational. Milly’s question of the Level Four Fax aboard The Witch of Agnesi was asked a thousand times an hour, somewhere in the system; but in fact there had never been a collision of two ships whose navigation systems were in working order. The OSL Achilles, outward bound for the Jovian system and Ganymede, crossed the trajectory of The Witch of Agnesi as the latter sped between the Jovian L-4 and L-5 points, and in celestial terms they made a “close approach” of less than two million kilometers. No human on either ship was aware of that fact.

The passengers of the Achilles were increasingly unaware of anything. Janeed had heard that in pre-war times a certain form of group mania infected the passengers of ocean liners. After the first few days nothing in the world existed beyond the ship, while what happened before and after the cruise became utterly irrelevant. A wild series of random courtships and short-lived affairs was the result.

Jan had hardly believed those reports, but now she saw evidence of their truth at first-hand. Colonists were pairing off, and as the ship drove outward toward its rendezvous with Jupiter an air of continuous festivity took over.

Not only the passengers were affected. The ship’s trajectory was computer-controlled, as were most of its on-board systems. The crew had time to relax. Paul Marr was able to devote a more-than-generous amount of time to Janeed. That certainly suited Jan. Within the first two days she had decided that everything she had been told about sex was right, or possibly understated. The more you did it, the more you liked it. The real danger was that you might become an addict. Jan suspected that she might be well on the way.

Occasionally, she would worry about Sebastian. She was seeing less and less of him as the days went by. On the other hand, Valnia Bloom seemed to be with him almost constantly. They spent most of the time hidden away in her private cabin. Jan didn’t think they were engaged in a sexual relationship, but even if they were, so what? Sebastian was a strongly-built and physically mature man in the prime of life. He and Valnia Bloom were as entitled to as good a time as Paul and Jan.

When she had boarded the Achilles, two weeks going on forever ago, Jan had expected to be impatient until the moment she set foot on Ganymede. Now, as that time of arrival came closer, she was loath to leave the ship. She and Paul had vowed that this would not be the end, that they would see each other again. But in reality, how many shipboard romances survived the day of disembarkation?

One major party still lay ahead. Jan had never heard of it before, but Paul explained as they lounged naked one evening in his cabin. The ship was in drive mode, and the two of them were reclining in sybaritic luxury on the most comfortable bed Jan had ever encountered. At the flip of a switch the floor had become soft and yielding, cushioned on the reservoir that contained the Achilles’ ample supplies of water.

She lay on her side, head turned to look across the flat plain of his chest and watch its steady rise and fell as he breathed. He had painted her nude, and when the picture was finished one thing had inevitably led to another.

“Of course the party isn’t necessary,” he said. “It represents a tradition from the earliest days of planetary exploration. The ships at that time all used chemical rockets—”

“Not nuclear?” Jan asked. “They had nuclear energy, you know, even back then.”

“They did, but they’d had bad experiences with it and a lot of people were still scared. So they used chemical rockets.”

“But the effects of chemical rockets on the atmosphere and ionosphere are a lot worse than nuclear. Didn’t they know—”

Paul had his arm around her and he gave her left breast a gentle squeeze. “Are you going to let me tell you about this, or do you want me to roll over and go to sleep?”

“Wouldn’t be the first time, would it? Go on, I’m listening.”

“The ships used chemical rockets. That’s not totally true, because there were already a few ion drives; but they provided such low accelerations that they were useless for passenger shipping. You can guess what it was like. Everybody was short of delta-vee for everything. They would scrounge, beg, or borrow as much momentum transfer as they could lay their hands on, but space travel was still marginal, all touch-and-go. The first ships to reach Jupiter didn’t have enough fuel to slow into orbit around the planet. If they didn’t do something different, they would arrive, swing past, and shoot away in some other direction. The answer — the only possible answer at the time — was to skim through Jupiter’s upper atmosphere and use air-braking for velocity-shedding.

“The theory was simple and fully understood for more than a century. Doing it, and getting it exactly right, was another matter. The Ashkenazy went in too deep and never came out. The Celandine erred in the other direction. It skipped in, skipped out, and left the Jovian system completely.”

His voice had gradually slowed and deepened. Jan squeezed the little roll of fat at his waist. “You’re supposed to be telling me about some big party we’ll be having, not zoning out on me. Are you drifting off?”

“I am not. I’m thinking how much easier we have it than the original explorers. The Celandine crew members were tough, and braver than you can believe. I’ve heard their recordings. They sent back data on the Jupiter magnetosphere until they were on the last drips of oxygen, then they all signed off as casually as if they were going out together for an early dinner. A dip into the Jovian atmosphere used to be a life-or-death proposition. Now it’s just a game. Jupiter’s atmospheric depth profile is mapped to six figures. The atmospheric swingby is a tradition and a good excuse for a party, but it is absolutely and totally unnecessary.”

“Like crossing the line.” She saw Paul’s forehead wrinkle. After sex he always seemed a little bit brain-dead. “In the old days of Earth-sailing ships, crossing the equator was a bit dodgy. The region around the equator was called the Doldrums, where the winds would fall away to nothing for days or weeks at a time. The ship would sit becalmed, in extreme heat, with no one aboard knowing if they would live long enough to catch a saving wind. Then steamships came along, and crossing the equator offered no special danger. But a ceremony called ‘Crossing the Line’ lived on. There were high jinks on board the cruise ships; parties and ritual shaving — not just of people’s heads, either — and silly ceremonies involving King Neptune.”

“It’s King Jove on the Jupiter flyby, but the rest of it sounds much the same.” Paul turned to look at Jan. “Look, I know it sounds stupid and it really is stupid, but as first officer I’m stuck with it. You don’t have to go along.”

“Are you kidding? Paul, there’s no way I’d miss this. If I had been there in the old days crossing the equator, I’d have been whooping it up like nobody’s business. My question is, can you as first officer take part in all the fun, or is it considered too undignified?”

“Define ‘too undignified.’ I suppose there are limits, but they’re pretty broad. On the last Jupiter atmospheric flyby, two months ago, the chief engineer dressed himself in a baboon suit. He had cut a piece out of the back. His ass was bare, and painted blue, and he said he was selling kisses. But I didn’t hear of any takers.”