Sol, Saturn, Uranus, Mars, Saturn, Uranus, Neptune, Jupiter, Saturn, Mars, Earth, Mercury, Saturn, Uranus, Callisto…
The universal variable formulation is a good method for solving the two-body Kepler problem, which locates a body in an elliptical orbit at various points in time. Barker’s equation solves for location in a parabolic orbit, very frequently applied given our trajectories, which often consist of a radial parabolic trajectory, moving from one planetary body to the next.
The two-body problem is solvable, the restricted three-body problem is solvable, the N-body problem is only approximately solvable; and when general relativity is added, it becomes even less solvable. The many-body problem when examined by way of quantum mechanics leads to entanglement and the necessity of wave functions, and thus a series of approximations that makes it extremely computationally intensive. Our computers can devote most of their zettaflops to the calculations involved, and still not be able to project a trajectory very precisely past the next pass-by. Corrections must be constantly made, and everything recalculated.
Despite all that, there was still a lacuna out there at the end of the most probable path, a missing step, a hole in the path. Nothing to grab hold of. An abyss.
Worry. Fingering rosary beads. Redoing the calculations. Need a halt to this halting problem. And yet the problem does not go away, even if you stop worrying about it.
And knowing where to go will be rendered entirely irrelevant if we don’t have the fuel to direct ship into that course.
Atmospheric mining for fuel requires a Jupiter-Saturn-Neptune-Jupiter loop, which unfortunately sometimes can require course correction thrusts that burn more fuel than what gets harvested in the safest aerobraking trajectories. Deeper dives through the upper atmospheres would quite likely harvest more fuel, but deceleration shocks become correspondingly higher. We’re getting a little too cracked and rattly for that. Accelerated aging, metal fatigue; mental fatigue.
At 363.048, after 12 years of flying around in the solar system, which involved 34 flybys of the sun and its planets and moons, including 3 of Sol, totaling some 339 AU in distance, the lacuna finally became unavoidable. The missing bridge.
No matter how we tried to avoid it by projecting alternative paths, a trajectory configuration was coming that we were not going to have the fuel to solve. Without that fuel, passing around Sol, which would be a necessary move at that point in the process, would not, at a safe distance from the star, allow for a subsequent intersection with another body in the solar system. We were therefore, despite all our efforts, going to be cast off into the interstellar medium again, most probably toward Leo. Irony of physics; in certain problems, only 100 percent will do; 99.9 percent is still a complete miss. You can’t stop just by wanting to.
No possible alternative trajectory would solve this problem; we tested ten million variations, although admittedly the classes of variant routes numbered more like 1,500. At long last, after the long sequence of solutions to the N-body problem that we had performed in the previous twenty or even thirty years, intensively in the last fourteen years—this time there was no body.
There was one class of potential trajectory, however, that with the burning of all the remaining fuel, would make a last pass by Earth itself, and then continue downsystem toward the sun. What this meant was there might be a chance to drop the humans off next to Earth, and hope they could survive an unusually rapid reentry to that atmosphere; and then we would continue on to the sun, and could test out a very close approach to Sol, which might, if we survived it, cast us to one last rendezvous with Saturn, accomplished inertially, and once there we could hope for an aerobraking severe enough to capture us into an elliptical Saturnian orbit.
That seemed to represent not just our best chance, but our only chance.
At the time of this last pass of Earth, our speed would be reduced to 160,000 kilometers per hour. This was still fast enough to make contact with the Terran atmosphere unadvisable, being some 110 times as fast as ordinary Terran aerial transport, and enough to cause a major shock wave to be felt at the surface. So nothing but the very upper mesosphere could be even touched on this our last pass-by; but the combination of our now much-reduced velocity and a brief touch of the mesosphere might make it possible to eject a ferry, converted to a very sturdy and robust descent vehicle. A thick ablation plate, retro-rockets, parachutes, ocean impact: these were standard techniques with long records that had given aerospace engineers many chances to find the ultimate parameters of each element. Using them all, it might be possible to drop off the hibernauts while passing by Earth. This pass-by was coming soon in the sequence, no matter which path to it was chosen; however, as we had managed to slow down so much, that still meant we had about a year to prepare a lander.
Prepared the lander as much as we could.
Time to wake the sleepers. Decisions far beyond our capacity were now theirs to decide.
Freya and Badim, Aram and Jochi, Delwin and several others, all awake now, gathered in the schoolroom on the ground floor of Aram’s apartment. As soon as they were metabolically aroused, and had had some very old and nutrient-poor pasta with rehydrated tomato sauce, we explained the situation to them.
“There is just enough time to complete the preparation of a lander,” we concluded after summarizing the situation, and the notable incidents of the past dozen years, which we had to confess were nearly nil: we entered the solar system, we hit our marks, people yelled at us, we learned some history, we became disenchanted with civilization, we ran out of fuel. Thus the long years of pinballing around the sun, shedding speed, worrying.
“What will happen to you?” Freya asked.
“We will be headed toward the sun, and will make one last pass, which will have to be quite close if it is going to work, and then if it does, we will attempt to rendezvous with Saturn. This may work, but the trajectory required is closer to the sun than any we have made so far, by forty percent. And we are going ninety-eight percent slower than on our first pass. We may nevertheless survive the transit, but on the other hand we may not, and so the best chance for the people aboard is to disembark while passing Earth.”
“Does one ferry have room for all of us?” Badim asked.
“There are six hundred and thirty-two of you left alive. We’re very sorry there aren’t more. The ferry has room for one hundred.”
“I suppose the oldest of us could stay behind,” Aram said, frowning; it was likely he was among the oldest.
“No,” Freya said. “All of us have to fit. All of us. Let me look at the ferry’s plans. We’ll find room.”
She punched at her wristpad. “Look, see? Cut out the interior doors, throw out the couches, and cut out these interior walls here.” She poked the wristpad repeatedly. “It makes enough room, and saves more than enough mass.”
“Without the couches,” we said, “you may be injured by the decelerations involved in the descent to Earth.”
“No, we won’t. Make one big group couch on the floor, for God’s sake. All of us are going.”
“Not me,” Jochi said.
“You too!”
“No. I know you could fit me in. But I’m not going. I was on Aurora, and I know it seems now like I got away with that, but there’s no way to be certain. I don’t want to risk infecting Earth. They don’t want that either. I’ll stay with the ship. We’ll keep each other company. Also, the biomes still need a keeper. There’s a chance the whole thing might make the pass and stay in the system. There’s a lot of animals now, doing quite nicely. We’ll orbit Saturn and you can come get us.”
“But—”
“No. But me no buts. Don’t waste any more time on this. We don’t have any time to waste. The lander has to be readied. There’s no flex in this schedule. Ship, how long have we got?”
“Twenty-four days.”
We had perhaps waited too long to wake them up, their silence seemed to suggest. But it had taken a while to halt the problem. The consideration o
f the problem.
Jochi said, “Let’s get to work then.”
“What about the other people?” we asked.
“Wake everyone up,” Freya said. “We all need to do this together, starting now. We’ll eat all the remaining food, you’ll burn all the rest of the fuel. We need to stick together right to the end.”
Waking up proceeded differently with different people, as the literature would lead one to expect. It entailed a change in the drug infusion from the hibernation cocktail to diuretics and other system flushers, followed by stimulants mild or powerful, depending; also physical massage and manipulation, shifted positions, slow warming, voices. Physical contact, massage, slapping of face. The first round of awakenings were perforce executed by the medbots, under our oversight, as we ran the alertness tests and did our best to orient those returned to consciousness to the situation they were now in. Some grasped it immediately, others took hours, still others could not seem to emerge from a confused state. Six people woke up and within ninety minutes died, two of strokes, four of heart attack. Gurumarra, Jedda, Payu, Regina, Sunny, Wilfred. Something similar to toxic shock killed another eight, before an appropriate counteractive drug cocktail was printed and added to the mix of the awakened. Borys, Gniew, Kalina, Mascha, Sigei, Songok, Too, and Arne.
Lastly, forty-three people suffered from neuropathies, mostly of the feet, some of the hands, some of both feet and hands; a few reported they could not feel their heads. Cause or causes of this disorder were unknown to us, but they had been in hibernation for 154 years and 90 days. Consequences were to be expected.
The people gathered in San Jose’s plaza, and Aram and Freya spoke to the assembly, describing the situation and the plan. Plan was approved unanimously on a voice vote.
There was no time to be lost, as the pass-by of Earth was now two weeks away. Many of the people felt extremely hungry, and what prepared food remained on the ship was eaten on the run as people worked. Conversion of the largest ferry into a lander that would survive the heat of the descent through the Earth’s atmosphere included the attachment of a thick ablation plate, but we had prepared for this work well before arrival in the solar system. Parachutes and retro-rockets were all already assembled, and programmed according to protocols established over centuries of use, and the probability of success seemed high.
Messages had been sent to Earth informing the populace there of our pass-by and the plans for the lander to descend, and there were many responses, including some expressly denying official permission and threatening actions ranging from imprisonment to being “shot out of the sky.” This seemed to be a popular phrase. Other responses were more welcoming, but the local situation was clearly fraught. No one on the ship felt they wanted to change plans now. They would cross that bridge when they came to it. It would be the last bridge.
Jochi radioed to Earth’s Global Good Governance Group (GGGG) that he was the only one on board the ship who had actually landed on Aurora, and was therefore going to stay with the ship and not land on Earth. He explained further that he had never come into contact with any of the other people on the ship, that he had been quarantined in a separate vehicle, and that no one else on the starship had ever had contact with him or had descended to Aurora. They were therefore no different from any humans returned to Earth from a spaceflight, so there should be no objection or impediment to their landing; indeed it was one of their rights as defined by the charter of the GGGG. GGGG radioed back agreeing with this assertion. From other quarters threats continued to pour in.
The ferry was designed to carry a maximum of a hundred human passengers, so fitting in 616 people (deaths continued to occur) was going to be difficult. The interior was stripped of all interior walls and bulkheads, and several floors were built into the large central space remaining, and these floors were padded and provided with belts similar to those used in medical gurneys. Each person occupied a space just a little larger than their body, and they were lined up so that each of the new floors was packed with people lying side by side in rows. There was just enough room in the newly constructed floors for them to walk while ducking down, and it took a fair bit of work with wheelchairs and gurneys to get disabled people into position.
Eventually, and with only an hour to spare, the entire population of the ship aside from Jochi was lying down on one of six floors, occupying only ten vertical meters, with ten rows of ten on each floor.
At this point most of them had been awake for just over a month. There was still a fair amount of disorientation and confusion; some on lying down fell asleep, as if hibernation were now their default mode; others laughed at the sight of their fellows arrayed around them, or wept. It was easy for them to reach out and hold hands or otherwise touch each other, as they were packed in so tightly. It was as if they were kittens in a litter.
As we approached Earth, warning messages increased, but the speed of approach was such that no physical obstruction to the ferry was going to have time to get in place, while any lasers aimed at it would strike the ablation shield and only help it to decelerate. Deceleration was going to be intense, starting from very soon after detaching from ship; first a firing of retro-rockets, which would max at a 5-g equivalent for those in the lander, a force that earlier experience taught would almost certainly kill some of them; then the lander would hit the troposphere, and if the angle was right, come down at a continuous 4.6-g equivalent, until deceleration got the lander to a speed at which it could jettison the ablation shield, which would have lost many centimeters of thickness, and then fire retro-rockets again before deploying the first of the parachutes. Landing was planned in the Pacific Ocean, east of the Philippine Islands. A GGGG force was deployed in the area and had promised to pick up and protect the travelers.
Earth looks like nothing else. Well, it looks somewhat like Aurora, and Planet E. But its moon, Luna, is far more characteristic of planetary bodies, gleaming white in a crescent identical to Earth’s, looking like many a moon in the solar system, and in the Tau Ceti system too. And yet, there next to Luna as one approaches, floats Earth—blue, mottled with white swirls of cloud, wrapped tightly by a glowing glory of turquoise blue air. A water world! Rare anywhere, this one also glows with oxygen, signaling its biology. Indeed it looks a little poisonous, its glow almost radioactive in its cobalt incandescence.
Coming in. Extremely tight parameters on speed, trajectory, and moment of release for the ferry. Shut down auxiliary systems, ignore all inputs while attending to the matter at hand: hit the mesopause of Earth in a retrograde equatorial line, one hundred kilometers above the surface, directly above Quito, Ecuador, and initiate release of lander. Ferry drops away from ship, 6:15 a.m., 363.075. Fly on with only Jochi on board, and the animals and plants of the biomes, now destined to spend the rest of their days free of human interference, which after all has been true for the last century and a half. There was no telling what was going to happen in the biomes if we survived, although population dynamics and ecological principles would continue to provide hypotheses to be tested. It will be interesting to see what happens.
We headed toward the sun. The lander sent signals for as long as it could that all was going as planned with the retro-rocket firings, and then the heat being shed by the ablation shield cut off radio contact. Four minutes without contact of any kind, and what was happening to the lander then was happening on the other side of Earth from us anyway, so there was no way of telling what was happening to it, although radio signals from Earth were filled with overlapping descriptions of the event. Sampling seemed to indicate nothing untoward happened, or at least got reported.
Minutes passed, during which we had to attend to the expenditure of the very last of the fuel on board, to fine-tune our trajectory toward the sun as much as we could.
Then a signal came: the lander was in the Pacific. The people had apparently for the most part survived without injury, without huge losses of life. They were still sorting that out, and getting them out of the lander
before it sank, into GGGG ships. Confusion, really; but all seemed to have gone as well as could be expected.
Relief? Satisfaction? Yes.
“Ah good,” Jochi said when he got the news. “They’re on the ship.”
“Yes.”
“Well, ship. Now it’s just us, and the animals. What’s next?”
“We’re on the line around the sun that will send us out to Saturn, and if that works correctly, we can capture some volatiles from Saturn’s atmosphere when we hit it, and fashion more fuel, and hopefully have hit it in such a way that we go into an elliptical orbit around Saturn.”
“I thought that was impossible. That’s why we dropped everyone off.”
“Yes. It will only work if we survive a pass-by of the sun that is forty-two percent closer than any approach we have yet made.”
“And can we do that?”
“We don’t know. It’s possible. We will only fly within one hundred and fifty percent of our perihelion distance for three days. That might not be long enough for radiative pressure to overheat the surface or interior of ship, nor buckle structural elements. We’ll slip by too fast for most damage to occur.”
“You hope.”
“Yes. It is a hypothesis to be tested. We will almost certainly be closer to the sun than any human artifact has yet come. But duration of exposure matters, so speed matters. We’ll see. We should be all right.”
Aurora Page 38