* * * *
She took the bubble ship up. As she rose, the rim of the sun appeared. The bubble darkened a little. The sun's rim was a bright red line storm with glimpses of yellow within, edging along a considerable span of horizon. She scooted away at the listed cruising speed, a hundred kilometers an hour, passing over dark circles upon dark circles, eons old.
Now she heard a whisper of wind. The cooling system hadn't been needed much until now. Motors pumped heat out through the plume, which glowed orange. A prominence lifted thousands of kilometers out from the sun, streaming, arching higher, reaching toward Mercury.
Joplee said, “Seventy hours."
The land was all craters and cracks. “Quicksilver, what's with all the canyons?"
"Oh, that's interesting, Kath. The early Mercury shrank as it cooled, of course, and the surface wrinkled a little. With almost no atmosphere the ridges don't erode very much. The thing is, it didn't wrinkle much either. The core never shrank enough for that. It's stayed molten for ten billion years."
"What's wrong with that? Mercury is right up against the sun."
"That's only since the sun's been expanding. It's a small planet, Kath. It would have lost that internal heat before there was a single human species. What keeps it molten is the sun's magnetic field interacting with the iron core."
"And that's you, Quicksilver?"
"Well, the flux tube was in place before I was, but I'm in there now. Picture my memory stored in core and my mind reaching through the magnetic lines toward the sun. Kath, that line of rock is part of the Hoplisht Rill.” A cursor danced along the horizon.
"You talk like a teaching program."
"I was a teacher.” The whisper of cooling had become a hum, and Quicksilver's voice rose. “After I chose this, I was a celebrity, the Mercury Mind. I was the ultimate data source for studies of the planet. We studied Sol too. But eventually there wasn't anything more for me to learn. So I taught visitors, children and adults. Teacher and guide."
"What's that?” She used the controls to put a cursor mark on what she'd seen on the surface. “Iron crab? It's as big as Midnight Dome!"
"No, not quite, but there are nine of those on Mercury. Mining systems from the Shibano Dynasty, each of them a little different. That's part of why people came to Mercury, Kath. Metals. They'd sink a shaft into the iron and siphon what they needed. Eventually the shaft would close again. They didn't want just iron, they wanted some of the impurities, so they sank shafts in different places."
"These drills still work?"
"Let me see.” A pause of several seconds. “That one does ... and ... four of them still come on."
The sun was a great red arc with a fuzzy, hazy rim. Mercury wasn't big; two hundred klicks could take you a long way around its curve. A wall rose over the horizon. She asked, “Caloris Basin?"
"Yes. Do you know what a planetesimal is?"
"Big mass, from when the solar system was just condensing. Enough planetesimals crashed together gives us planets."
"Yes. A planetesimal hit the Earth and gouged out a ring of debris that condensed into the Earth's Moon. Another one hit here and made Caloris Basin. But look at how regular it is, Kath.” Caloris was a perfect circle around a nearly smooth floor. There were thousands of craters inside it, the marks of later strikes, but of large craters there were none.
"Whatever hits Mercury hits hard,” Quicksilver said. “Anything that gets this deep in the sun's gravity well has huge kinetic energy. The strike that made the Caloris impact must have made a very hot fireball. It didn't rise, not in vacuum. It would have hovered like a flaming leech, melting everything."
Kath tried to imagine it. Then, “Show me."
"I picture it like—” The image formed slowly, then lurched into motion. A small moonlike body flew tumbling from offstage, glowed at its forward rim, and struck. A hemisphere rose glare white and symmetric from a darkened primordial landscape. “—like this.” It expanded to engulf Kath's viewpoint, and now they were inside the fireball. Rock sprayed.
Kath tired of being blind. “Enough."
Black sky, tongues of corona, red sun. The bubble ship continued its descent into Caloris Basin. Kath spotted a silver crab-shape near the rim.
Quicksilver said, “Red giant stars aren't as well behaved as we once thought."
"Oh?"
A glare-white storm was rising from the red arc of the sun. The vehicle's drive stuttered.
"Quicksilver?"
The voice of Quicksilver was silent.
"Joplee, land us safely."
The bubble ship's drive steadied, then drove hard. Kath sagged in her couch. It reclined her, enclosed her tenderly. She spoke with difficulty. “Joplee, what's going on?"
"A solar storm, Kath. Let me work. If I can't compensate for this mag whorl, we'll tumble."
"How's the radiation level?"
"High and growing, but it's no threat to me."
"What about me?"
"It will kill you in perhaps twenty hours."
"Joplee, land us near that digging machine."
The bubble ship surged sideways, then back. It came down with a jolt. Kathlerian felt small next to the iron crab.
"Kathlerian?"
"Quicksilver! Where did you go?"
"Magnetic fields disordered me. It could happen again. Kathlerian, you're endangered. Radiation—"
"I thought maybe I could dig in. Quicksilver, can you start that digging machine?"
"No, I don't have any such control over Mercury's industrial facilities. Work through Joplee."
"Joplee, I want to dig a big hole, fast. Can you—?"
Dirt sprayed back from the huge machine, jetting into the sky. Joplee said, “This is expensive, Kath."
"Give me a depth reading."
"The machine had already dug point eleven kilometers down when it was stopped. Now point fifteen."
"Quicksilver, does that look deep enough?"
"Go for point three klicks. Then get into it quickly."
* * * *
The machine had gone in at an angle. Kath settled the bubble ship into the black depths, extruded tractor treads and rolled under the digging machine. Its huge mass would be some protection too.
The vehicle's air conditioning hummed, but the feather plume wasn't dumping heat into black sky any more. Hot rock surrounded them. The cabin grew warm.
Joplee was cut off from the Midnight Dome. He could still monitor radiation, still keep time.
Quicksilver went silent.
Kath waited with dwindling patience through fifty hours underground. Then Joplee announced, “Twenty hours to departure. Kath, radiation levels are falling."
"Safe enough for me?"
"That depends on your purpose. If you intend to return to Midnight Dome, then the shielding will hold at present levels. To circle Mercury would certainly kill you. Do you want to be told this kind of thing?"
"Yes.” The altered Joplee knew what the old Joplee knew, except to protect her. Maybe if she knew what to ask, he could help save her after all.
The bubble ship's magnetic lift system wouldn't lift.
Kath tried not to think about what that meant. She extended tractor treads and crawled out of the slanting hole and into the glare. The sun didn't look much different from when she had last seen it, but now it seemed scary. She extended wheels and set off around the curve toward Mercury's dark backside. Her explorations had missed most of the planet.
* * * *
Twenty hours later she saw a silver lens lift above the close black horizon. Joplee had finished his countdown: she knew what to expect. She zoomed the forward view and saw Naglfar Marui pause above the glaring mountains, then dwindle rapidly against the black sky.
They'd left her. She was angry, then ashamed, then—"Joplee, can you call Naglfar?"
"Yes. Whom will you speak to?"
"Anyone."
She got Zesh Folty. The silver egg was hysterical with relief, then horror. “But you're
trapped!"
"Can someone send a lifeboat back for me?"
"Oh, Kath, we can't interrupt the systems. Mercury's already in the photosphere. Naglfar Marui is our last chance. We looked for you. Have you tried to reach your, um, protector?"
"Jerian? No, I called you first.” Jerian would be furious. Or indifferent. Would he actually want Kathlerian 771 returned to his breeding pool? She could guess at the cost of rescuing her: it would be astronomical, if it could be done at all.
"I'll set a system to monitor you,” Zesh said. “Where are you?"
"On my way to the Dome."
"Call your Jerian."
There was no escape. “Joplee, call Jerian Wale, site unknown."
"Kath, your vehicle's design doesn't include long range communication. I can't reach any sources more distant than a few million klicks. You should try again when we reach the Dome."
"When will that be?"
"At this pace, one hundred thirty hours."
Too long! “Will my supplies last?"
"Your water will run short. Oxygen should last long enough."
Horror crept up the back of Kath's neck; her ears and nostrils and fists curled tight shut. “Water?” Run short, in this oven? “Maybe there are some caches somewhere? By the drilling machines?"
"Probing with radar. No."
"Are there machines or vehicles in the dome that can bring me water?"
Joplee went still for a moment, probably communing with the dome. “They've been packed away. The dome believes it's closed, they won't respond from here. I could change that from inside the dome, but not from here."
She put her head in her hands. Why had she overridden Joplee? The silent dark rocks of Mercury passed by her view. Headstones. She had to think. "Wait. Joplee, my food is stored dry, isn't it?"
"Most of it is."
If she stopped eating, she'd have more water. Joplee should have thought of that. Her first move upon reaching the Dome was going to be to put Joplee back the way he'd been.
Every few waking hours, Kathlerian called for Quicksilver. There was no answer.
* * * *
Kathlerian held her breath as they drove up to the dome. Would the doors open?
They did.
She wobbled into the Dome, her stomach tight and angry, Joplee humming at her heels. She could feel the emptiness, the stillness. Oddly, the dome still supplied running water to its sinks. She ran water over her hair and face and drank from her cupped hands, dripping water from her chin. The suit landed in a corner and she wrinkled her nose at the sharp sweaty stink of her skin. Finding a fresher would take too long. Minutes was too long. She started a sponge bath. “Joplee, get me a fruit basket."
"Which fruits, Kathlerian?"
"Some of everything in memory stores, a kilogram total. Send it here."
"I cannot find transport."
She sank down into a chair, the dry hot air of the dome melting dampness from her skin. Where machines had been there was only silence. All the robots must have gone into storage. “Revive some machines, Joplee. Get me a fruit basket and some corn bread. And pull the temperature down some."
"In process."
Kathlerian created a wall niche and monitor surface. As she worked, a small window popped up: a display of the expenses she was incurring. Daunting ... but the Dome must have registered her as an emergency rescue project. As the last occupant of the Dome, her reserve was huge. The kicker was that it would have to be paid back, if she lived.
There were delays: much of the works had been shut down.
She was greatly relieved to find Joplee's mind still in storage under her label: Joplee Base Program.
Shut down Joplee? No, she'd have to re-order through the wall interface. She was famished! All right, call Jerian while she waited. She tapped instructions.
The words “Outside Transmission Shut Down” floated across her screen in bright yellow letters.
A robot, a float plate a meter across, arrived with fruit and a hot loaf of corn bread. Kathlerian ate while she worked the keyboard. Exterior cameras were still running, most of them. Antennas built into the roof's curved surface had a softened look. They were being etched away much faster than they could rebuild themselves.
Could the Dome build her an escape craft? “Quicksilver?"
No answer.
She'd better work through Joplee, after she gave him back his mind. The Joplee Base Program had grown into his original instructions: protect a little girl against her own mistakes. Joplee would have that talent again.
"Joplee, choose me a dinner."
"Yes, Kathlerian.” Joplee froze.
Rebooting Joplee was much easier than rewriting him had been. She finished the fruit and bread and ordered a mug of stim and an overstuffed cheese and tomato handmeal with everything, using the wall connection, while she waited. In the wall screen Joplee's mind was a complicated three-dimensional shape, changing, turning.
Lights blinked on Joplee's extensors. Kath said, “Joplee?” a bit apprehensively.
"Kathlerian."
"I need to build—"
"Reviewing. You may not go out. May not build. Surface conditions are. I've killed you."
"It's all right. We'll get out. We'll just—” Joplee's lights went out. “Just build a ship. Joplee?” In the wall screen Joplee's mind had become a featureless blue sphere. She stared into it, momentarily lost.
All right, now, that didn't work, but no civilized entity would be stopped by one programming mistake. Maybe if she talked faster?
She set Joplee to reboot, and waited. When lights flashed she said rapidly, “We have to build a spacecraft, Joplee."
"Reviewing."
"Abort review. See if Midnight Dome can build us a spacecraft."
"Antimatter stores are depleted. I can't get you fuel, Kath. The Dome is deserted. We've missed Naglfar Marui.” Joplee's lights went out. Blue sphere of death.
She carefully made a copy of the Joplee Base Program. She'd work with that and reserve the original.
"Kathlerian?"
"Quicksilver?"
"Yes. You missed your ship.” An echo of Joplee's last words.
"At least the radiation didn't get me. Are you all right?"
"Diagnostics suggest some corruption. You should work through Joplee."
"I can't reboot Joplee!” Her voice became a squeal.
"What have you tried?"
Kathlerian began a tearful review. Quicksilver interrupted: “I understand. He sees that he's risked your safety and he can't tolerate it."
"But he could save us. He can build us a ship. I'm registered for Emergency Survival Funding. There's plenty of credit."
"Can you reload the Joplee version that went out with you?"
Kathlerian sniffed. “I didn't save it."
"Use the wall connection. Try to design something."
Kathlerian set to work. It occurred to her to ask, “How are you doing, Quicksilver? Is the sun hurting you?"
"I'm having trouble concentrating. There's magnetic kinking in the flux tube. It's like being kicked in the head at random intervals. Kath, your problem is with the armor. If you armor a ship enough to protect you, it won't lift you to safety."
"Antimatter is very powerful stuff,” she said.
"You need too big a ship. I find two antimatter motors, both too small, and only dregs of an antimatter reserve. The best drive systems from the old ship junkyard were all reworked and integrated into Naglfar Marui. Wait, now, I've found some fusion drivers from a long time ago, and there's all the water in the Dome for your hydrogen ... mmm ... no."
"There were other bases. Whole industrial cities."
"I remember. There was a molecular pump, too, right here, just outside Midnight Dome. Mercury's atmosphere is all protons from the solar wind, all ionized hydrogen: very thin once, but thicker now. We could have done something. But the pump system is long gone. So are the cities."
Kathlerian ordered an elaborate dinner. She was reco
vering from partial starvation, and her brain needed fuel, she told herself. Half of what she ordered was rejected. The Dome had lost much of its stores and its capability, and the Vivarium wasn't producing fresh food—nor fresh air.
She asked, “How long have we got?"
"Mercury has centuries. Mercury's surface, much less. The Dome might survive two years. Stores ... the recycling system is quite advanced. Three to ten years."
"Longer than the Dome? Wait, now, I could dig. Cover the Dome with rock. But it couldn't radiate heat then, could it?"
"No. I don't see a solution."
Joplee was no help. She couldn't revive Joplee unless she could present him with a way to save them. What now?
"I have a notion,” Quicksilver said.
"See if you can describe it."
"You'll think I'm crazy. Hey, I am crazy, a little."
"I am not inclined to be picky!"
"I have magnetic fields for thrust and iron for reaction mass. We could accelerate the planet to a wider orbit."
Her eyes bugged. “Turn Mercury into a rocket? Are you-?” Crazy. She didn't say it.
"All I lack is a rocket nozzle. You would have to dig a hole all the way down to the core. We'd be working at Mercury's aft point, the West Pole, you might call it. But I don't control the digging machines."
Kathlerian's fists, ears, eyelids all clenched tight. She was only thirty-one standard years old! This was all Jerian Wale's fault. If he'd listed her as an adult, she'd be working directly through the base systems! But a child had to work through her guardian.
Joplee was only a machine. Must she pay with her life for mistreating a machine?
Kathlerian spoke slowly, feeling her way. “You can jet iron?"
"Iron plasma at high exhaust velocity."
"Why not just use that to dig your way out from the core?"
"Yes, Kath, I can blast away twelve miles’ depth of regolith, but it would spray silicate meteors all over Mercury's surface. Midnight Base wouldn't survive. You wouldn't survive."
"But you would. Mmm?"
"Yes. I can compute a path to keep me safely distant from the sun, yet close enough to keep the flux tube in place; moving ever out as the sun expands. But I don't think the solar system's defense systems would allow me to do anything so reckless, unless I was acting to rescue, say, a little girl."
Asimov's SF, August 2005 Page 11