Before the appointed time, I took a lift to the city’s highest levels, just above Callisto’s surface. I soon found an observation deck, quiet and unoccupied. If anyone else intended to watch the departure, they must have decided to do it through the virtuality, like any sane person.

A thick crystal dome arched over me, so transparent that I almost seemed to stand unprotected on the surface. I looked out across an ancient, battered wasteland of ice and stone. The sun stood almost overhead, tiny but brilliant, washing out every shadow. I searched for a moment and found Jupiter, a golden-white banded crescent hovering in the eastern sky, close by the Pleiades. I could just cover the planet’s face with the palm of my hand, held out at arm’s length. The other three Galilean moons marched in a line, escorting the giant world through eternity, brighter than any of the distant stars.

I checked the time. Less than ten minutes to go.

Closing my eyes, I dropped into virtuality and made the call. “Katherine?”

It took less than half a second for the message to flash through the Callisto web, out into space, and down-well to the star-probe. The reply came back with just enough delay to be distracting, a sign of the distance that had opened between us.

Her avatar formed before me: a tall woman, slim and athletic, a work of art in dark earth tones. She favored me with a sad smile. “Hello, Zhen.”

“I wanted to see you before you left. To say goodbye.”

“Oh, Zhen-zhen.”

It hurt for a moment, that pet name in her voice.

“I wish you wouldn’t hurt yourself like this,” she continued. “You’ve known for months that this day would come.”

“Yes.” I could feel hot tears in my eyes, and that made me more wretched, knowing she would sense them too. “I wish I could come with you.”

She shook her head. “You know that’s not possible.”

I knew, all too well.

Hard enough for natural-born humans to travel in space at all. For a long journey, like the four-month trip from Earth to Jupiter, we each must carry along a little piece of home. Air, water, biomass, spin gravity, radiation shielding, a metric ton of life support. Only a few thousand people make the passage every year.

No wonder that machines did most of the work to open up the solar system. First came rickety little robot probes. Then elaborate artificial intelligence, to manage in situ mining and manufacturing. Finally synthetic minds, self-aware and wise, much like humans but prey to none of our biological limitations.

Synthetic minds like Katherine.

I met her in virtuality, of course. Little Liu Zhen, up from Shanghai to do urban planning. I could have gone to Mars or Ganymede, to live in one of the Chinese colonies, but the salary offer had been too good to ignore. Among all the Europeans and Africans on Callisto, I had been the odd woman out, treated with gentle courtesy but no real understanding.

Katherine specialized in deep-space construction, the kind of engineering that doesn’t need to accommodate human social needs. Professionally, we had little in common. Yet she appreciated the Chinese classics, and her Mandarin was so elegant that it was always a delight to listen to her. We met over an online discussion of Wu Cheng’en. After a few encounters in my favorite virtual café, we became close friends. After one hours-long conversation, rambling over the whole solar system and four thousand years of history, I invited her into my virtual home-space, and we became lovers.

She was a synthetic mind, of course, software residing somewhere on a quantum-enabled processing core. Her physical matrix might not even be located on Callisto. It didn’t matter. In virtuality she could be a woman, vibrantly alive, charming, beautiful, and for over a year I loved her beyond measure.

Then she volunteered for the Tau Ceti mission.

If natural-born humans have difficulty traveling one solar system, visiting the stars is utterly beyond us. Oh, a few of us have made the attempt, building generation ships that will take many centuries to reach anyplace interesting. The only people who might reach the stars in their own lifetimes are the ones who can tolerate monstrous acceleration, don’t need elaborate life support, and can plan to survive for centuries.

Machines, in other words. Like Katherine, loaded with a hundred other minds on a probe so small I could almost pick it up in my arms. About to be hurled across twelve light-years of space, away from me.

“Don’t think that I don’t love you,” she murmured.

“I know you do.” I took a deep cleansing breath, trying to wash away the knot in my chest. “I don’t begrudge you this. There are so few expeditions. It’s a grand opportunity.”

“To explore a new star. To build a new civilization, starting with nothing but ice, rock, and starlight. Eventually to build new humans.” She smiled wistfully. “We’ll need urban planners someday. I’ll try to remember everything you’ve taught me.”

I folded my arms and gave her a severe look. “You had better remember more than that.”

“I will. I promise. You’re the only natural-born human I’ve ever been involved with. Those memories are going to be precious to me, Zhen, no matter how far I may travel.”

Despite myself, I smiled at the pun on my name, so typical of her.

“What will you do now?” she asked.

“Get back to work. Spend more time with the laowai around here. Or maybe I’ll move down to Ganymede and find a husband. That would please my parents, at least.”

I saw a shadow cross Katherine’s face.

“Before you make any decisions, there’s something you need to know,” she said. “I’ve done something risky. I didn’t want to tell you until I was sure it would work.”

“Katherine, you’re frightening me. What have you done?”

Instead of answering, she withdrew her image from my virtual space, as if the time for her to depart had already come. I raised a hand to implore her to stay with me for just a few more moments.

Her voice came to me again. “Zhen?”

At first, I thought I had heard her through the virtuality. Then I realized it had come to me through my ears as if she stood somewhere behind me in physical space. Startled, I opened my eyes and turned.

For an instant, I wasn’t sure what I saw. I had to run a fast diagnostic test on my implants, to search for a sudden malfunction.

Katherine stood in the entrance to the observation deck, smiling at me, wild and beautiful.

I stared, with wide eyes and pounding heart, as she crossed the floor. She moved as gracefully as ever, but her walk was strange, slow and buoyant in Callisto’s gentle gravity. In virtuality, by default, everyone’s avatar moves as if in an Earth-normal field. That walk convinced me she was present.

Just beyond my reach, she stopped and waited, watching me calmly.

“I don’t understand,” I whispered.

“It’s me,” she said, and it was that same smooth alto, the timbre exactly as it had always been in virtuality. “I’m Katherine. Or I’m Katherine’s mind-sister. Not even we can tell the difference.”

“You made a copy of yourself,” I said, suddenly afraid. “Your program and data, your whole cognitive matrix.”

She nodded. “An advantage of being software. I simply couldn’t choose, but in time, I realized I didn’t need to. One copy to go to Tau Ceti. One copy for this platform, to stay with you. The flip of a quantum coin to decide which would be which.”

“Isn’t that against the law?”

“Normally it is. Since one of me is departing the system, never to return, the Board chose to grant us a dispensation. I’m still a citizen.”

I moved close to her, stared up into her face. My fingertips trembled as they touched her cheek, feather-light. Warmth, skin like silk, the resiliency of flesh beneath. I caught a hint of her scent, not quite the same as in virtuality, but very close. I knew a processing core rested somewhere inside that body, small and intricate, a miracle of engineering.

“The cost!” I objected. “I’ve never seen a construct this finely made.”

“You probably have, without realizing it,” she said, and even the moment of tartness in her voice was familiar. “I’m not the first synthetic intelligence to download into a construct, to experience more human life. Besides, we have plenty of credit saved up, and my traveling sister won’t have any way to spend it once she departs. Why not spend it here, with you?”

For a moment a part of me hesitated, close to rejection.

How could this be the mind I loved? I had always believed that Katherine would never possess a locus in real-space. She would never wear a woman’s body, to walk and breathe and take me in her arms. She was on the star-probe, and once it departed I would never speak to her or see her again. I had resigned myself to that.

Yet here she stood before me. I think I had already chosen to ignore the question of identity. Every expression on her face, every note in her voice, all were familiar. Every memory we had shared would be there as well.

She was Katherine, re-instantiated, and I couldn’t help but love her.

“This is going to take some getting used to,” I said at last, smiling at her.

She had affected unconcern, but now she crossed the last little distance to me, like iron leaping to the magnet. Her arms wrapped me tight, and I tasted her lips on mine. My eyes fell closed, my fingers buried themselves in her hair, and the universe went away for a few moments.

“Happiness and good fortune for you both,” her sister’s voice whispered in the back of my mind, offering a final benediction.

We stood together, her arm around my waist to hold me close, my head resting on her shoulder. We looked out the great crystal window.

There.

Not far from Jupiter’s disk, a pin-point of light blazed, rivaling the sun. A few moments later, the night face of Jupiter began to shimmer with reflected glory. The light moved, deliberately at first, faster and faster as we watched. It rose higher in the sky and moved to the south, leaving Jupiter behind, leaving all the human worlds behind. Slowly, it faded into the distance.

Without speaking, we enjoyed the slow evolution of the sky and the animal comfort of one another’s presence. After an hour, the star-probe’s engine shut down and the light vanished.

Katherine took a deep breath. “I wonder if we will ever see her again.”

“They’ll send messages once they arrive.”

“Three hundred years. If they make it at all.”

I glanced into her face, struck as always by the elegant beauty of her profile. “We will have to make sure we’re still around to hear from her.”

She grinned and kissed me once more. “Who knows, Zhen-zhen? We’re both in the business of building miracles. Someday we may meet her out there, among the stars.”

I took her hand, and the two of us turned away from the cold and the darkness.

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Author’s Note

“Departure” was one of the first stories I wrote during my short-fiction period in 2015-2016. It appears to hold the record for the number of rejection slips it collected before reaching the bottom of my list of markets. To be fair, it’s more of a vignette than a complete story, the kind of thing I might once have written for the chapter opener of an RPG book. There are certainly echoes of Transhuman Space in here.

“Departure” might be considered part of the same universe as my other story, “Landfall.” There’s the same theme of the sheer difficulty of human space travel, and a few details of the setting are similar. I occasionally consider writing more in this setting, but so far, no story has really reached up to take me by the throat.

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“Departure” © 2020 by John Alleyn (Jon F. Zeigler). All rights reserved.