Aurora (57 page)

“No. Twelve years, we reckon, plus or minus eight years.”

Jochi stopped laughing, and smiled at Freya. He made for a very amused face, there on her screen. “We can just keep hibernating till it’s over, right?”

Freya put her hands to her head. “More?”

“It won’t make much difference.”

“Well, I hope more of my body doesn’t fall asleep! My feet are still asleep!”

We said, “We can work on your neuropathy while you continue your dormancy.”

Freya looked around. “What will happen to you, after we’re dropped off on Earth, assuming it all works?”

“We will try to pass by the sun one more time, in a way that allows us to head out and aerobrake around one of the gas giants, and park the ship in orbit around that gas giant,” we said. This was quite a low-probability event, but not impossible.

Freya stared around herself, seeming disoriented. Screens showed the stars, with Sol now by far the brightest at magnitude. 1. We were just over two light-years away from it.

“Do we have any choice?” Freya asked. “Are there any alternatives?”

We said, “No.”

Jochi said, “This is what we have.”

“All right, then. Put us back to sleep.”

“Should we wake Badim and Aram?”

“No. Don’t bother them. And, ship? Be careful with us, please.”

“Of course,” we said.

The following years passed quickly or slowly, depending on the unit of measurement applied, as we prepared for arrival by further hardening the ship, and making calculations for the best trajectory, and adjusting our course to the deceleration of the laser beam, so that we were headed for the solar system where it would be when we got to it, rather than firing past well ahead of it, so to speak. When we hit the heliopause, we turned on the magnetic drag field, for what it was worth, and burned some more of our precious remaining fuel, to slow down a bit more before reaching the solar system. It was clear that every kilometer per second might matter on that first pass-by of Sol; we needed to be going as slowly as possible when we got to Sol, while still having some fuel afterward for maneuvers. It was a tricky calculation, a delicate balance. The years passed at a rate of trillions of computations per second—as it does always, one supposes, for every consciousness. Now, is that fast or slow?

When we crossed the orbit of Neptune, still going 3 percent of the speed of light, a truly terrible situation, a runaway train like none ever seen, we burned our fuel as fast as the engines could burn it, decelerating at a rate equivalent to about 1 g of pressure on the ship. Really a good sharp deceleration, and quite an expense of our precious remaining fuel; and yet nevertheless, we were going so fast that even slowing as we were, by the time we reached the sun we would still be going over 1 percent the speed of light. Arguably a unique event in solar system history. In any case very unusual.

Luckily, lag time in radio communication with our interlocutors in the solar system was now reduced to just several hours,
so warnings had been conveyed, and the occupants of the solar system knew we were coming. That was good, as it might have been quite a surprise to see such a thing coming in out of the blue, flying in from left field. From the orbit of Neptune to the sun in 156 hours; this was a great deal faster than anything substantial had ever moved through the solar system, and the friction of the solar wind against our magnetic shielding, and the drag around us too, like a big parachute or sea anchor (although not very much like), caused a quite brilliant shower of photons and heated particles to burst away from us, light so bright as to be easily visible even during the Terran day. From all accounts we were a small but apparently painfully bright light, moving visibly across the daytime sky. It was obviously shocking to the humans in the solar system to see any celestial object in Earth’s daytime sky except the sun and moon, also shocking to see any celestial object move at speed across the sky; shocking, and because of that, frightening. Possibly if they could have destroyed us they would have, because if we had for whatever odd reason headed straight at Earth and struck it going the speed we were going, our impact would have created enough joules of energy to wreak quite a bit of damage, possibly including the complete vaporization of the Terran atmosphere.

Did not run the calculations to check on that rough estimate of the effects of such a hypothetical calamity, because it wasn’t going to happen, and all of our computational capacities were busy fine-tuning our first approach around the sun. This was the crucial one, the make-or-break pass. We were going to approach Sol with our magnetic parachute arrayed around us, which would interact with Sol’s own magnetic field and because of our high speed work quite effectively as a drag. It was already helping us to slow our approach to Sol, which because of Sol’s own gravity would otherwise have caused a considerable inward acceleration. So the magnetic parachute was a major factor, and calculating its drag one of the many problems we were now solving, staying just ahead of real
time despite devoting a hundred quadrillion computations a second to the problems as they evolved.

We would be swinging close by Sol, catching our first gravity drag with a U value that was a significant fraction of Sol’s local motion. By firing our rockets against our own motion in the seconds closest to perihelion, we would greatly leverage the deceleration of Sol’s gravity drag, and also be aiming the ship at Jupiter, our next rendezvous.

This pass was going to occur very quickly. All the masses, speeds, velocity vectors, and distances involved needed to be assessed as closely as possible, to make sure we would be headed to Jupiter after the pass-by, after losing as much velocity as possible without breaking the ship or crushing the crew. It was a bit daunting to realize how fine the margins for error were going to be. Our entry window would be no larger than about ten kilometers in diameter, not much bigger than our own width. If the distance from Sol to Earth (or one AU) were reduced to a meter (a reduction of 150 billion to one), Tau Ceti would still be about 750 kilometers away; so hitting our entry window on a shot from Tau Ceti was going to require accuracy in the part-per-hundred-trillion range. Eye of the needle indeed!

And it was going to be a hot and heavy pass. The heat was the lesser problem, as we would be near the sun for such a short time. During that time, however, the combination of the deceleration and the tidal forces exerted while swinging fifty-eight degrees around the sun would combine to a brief force of about 10 g’s. After study of the problem, we had first tried to construct the trajectory with the idea of holding to a maximum of 5 g’s, but in fact getting headed toward Jupiter, given our incoming trajectory, required risking a higher g-force. We were happy that we had spent the last century reconfiguring the ship to a much more robust arrangement, structurally very sound, in theory; but there was little we could do for our people, who were going to have to experience
what was going to be a potentially rather traumatic, indeed possibly fatal, squishing. Cosmonauts and test pilots had briefly endured gravitational forces of up to 45 g’s, but these were specialists bracing themselves for the experience, while the hibernauts were going to be taken unawares. Hopefully they would not all be squished like bugs. We did not like to be subjecting them to such an event, but judged it was either that or a subsequent death by starvation, and what we had seen of their approach to starvation indicated that would not be a good way to die. As it was, our attempt to stay in the system represented at least a possibility of survival.

Unfortunately, our first approach to the sun had to be adjusted by a pass-by of Earth first, this not to slow us down at all, but merely to help our angling toward Sol. Luck of the draw, really: alignment of the planets in this CE year 2896, year 351 ship time, was actually one of the few alignments that allowed for even a theoretical chance of this maneuver succeeding. So, first up, a close pass of Earth at 30 million kilometers per hour. It seemed likely people there were going to be alarmed.

Indeed it proved so. Possibly justified, in that if we happened to be approaching in order to enact some kind of suicidal vengeance on the culture that had cast us out to the stars—a desire very far from us, being a starship, after all—then a direct impact into Earth would have struck at about ten thousand times the speed of the KT impact asteroid that had wreaked so much famous damage, and this would definitely have rapidly distributed a lot of joules. The assurances that we sent Earthward that we did not intend to auger in were not universally believed, and as we crossed the asteroid belt and came on down, radio traffic from Earth was full of commentary, ranging from trepidation to outraged panic.

We flashed by and left them agog. Their radio bands squawked as if a chicken yard had been swooped by a hawk. Happily they were not left in suspense for long as to our intentions, as we crossed cislunar space in fifty-five seconds. Obviously this must have been a dramatic sight. Apparently we passed by the Eastern Hemisphere, crossing its sunset terminator, so that those in Asia saw us as a streak in the night sky, those in Europe and Africa, in the day sky; either way, our luminosity was such that astronomical sunglasses were required to look at us safely, and it was said (possibly incorrectly) that we were for many seconds far brighter than the sun. A streak of light, blazing across the sky.