"Well, I don't know how to fix it," Marna announced, flopping back on her heels and glaring into the entrails of the life support computer. She pushed her copper-gold hair back out of her sweaty face, adding another streak to the grime that almost hid skin the color of ivory buried for millennia. It had been close to two centuries since a R'il'nian hand had touched the system, and even in the closed environment of a sealed dome on a satellite, dust accumulated.

Beside her, Ruby trilled anxiously, and Marna looked ruefully down at the tineral. Huge dark eyes returned her gaze from the catlike face, and small hand-paws twisted together uneasily. The tiny scarlet feathers that covered the face and the thin, monkey-like body were still bright, as were the feathered wings that now served only as a weather cloak, unneeded in the domes. As a juvenile Ruby had flown with those wings, exploring every cranny of the complex of domes and tunnels. Her younger relatives still flew and sang their clear, fluting songs in the dying trees.

Ruby wasn't full-grown. A tineral grew throughout its life, its voice deepening and mellowing as its body enlarged. A really old tineral, like Onyx, would mass over half as much as Marna herself, and have a voice like a bass violin. Ruby was almost breeding age, though no larger than a R'il'nian baby, with a voice that blended clarinet and viola. She had grown too large for her wings to support in the Riya-normal gravity Marna insisted on maintaining.

Marna sighed, feeling as if the station had betrayed her. She'd lived here for two of her three centuries, with only the tinerals for company. "I can't fix it," she told Ruby. "So we're going to die, just as I should have died with everyone else, two centuries ago."

Even now, the memories of that time were hard to face. She was a Healer, and the horror of being ordered to remain in safety on the isolated satellite while the population of her planet was dying had almost destroyed her. Only her mentor, Tyr, could have compelled her obedience, and his dying words still rang as clear as if he had just placed them in her mind: I do not think we will find a cure in time for this plague. Already half of our people are dead, and most of the rest of us are dying. Someone must live and warn off any who may come, Marna, and as you are where we can hope the plague cannot reach, you are our best hope. You must not return to Riya, even if the plague kills us all and seems to have burned itself out. How ironic, she had often thought, that she, who had been willing to risk her own life to study a new and potentially threatening pathogen, should be the only and most unwilling survivor of the R'il'nai. The isolation designed to shield the population of Riya from a threat that had proved to be no threat at all had instead shielded her from the death of her planet.

Wearily she stood, brushed futilely at the knees of her coverall, and began wrestling the cover panel back into place. Ruby, always eager to imitate her, caught at a corner just as Marna was snapping the panel home and squealed in pain as her finger was pinched. Hastily Marna freed the little paw and shouldered the panel the rest of the way into place. She held the injured paw lightly between her own finger and thumb, reaching deftly into the little animal's mind and through it, into the damaged finger. Block the nerve to stop pain, first, then reknit the crushed and torn capillaries and remove pooled blood. Check the bone—undamaged—then repair muscle, connective tissue and skin. In less than a hundred breaths she released the nerve block, dropped her hold on the paw, and scratched Ruby affectionately between the wings.

"I wish I could Heal the life support system as easily as that," she said. She had Healed it in the past, when a living part of the artificial ecosystem had faltered. But the satellite station was too small to support a truly self-regulating ecosystem, so computer control was needed to keep it in balance. The computer, unlike the large planetary one on Riya, was not self-repairing. And repairing the computer was totally beyond her ability.

The tinerals didn't understand her words, she knew. They were biddable, easily trained, responsive to her emotions, and glorious singers, but not particularly intelligent. But she needed to talk, and they were the only listeners she had. Ruby caught at the leg of her coverall, and she let the little animal lead her out of the computer room.

Feather trees should have made a green dimness of the large dome but the skeletons of their leaves, drained of life by sap-sucking insects the computer encouraged rather than controlled, crunched dryly underfoot. The tinerals, accustomed to supplementing their cultured diet with fresh fruit and nuts, searched vainly among the dry, increasingly brittle branches. A group of the older ones, including Ruby's mother Sapphire, cried musically as Marna passed them, their voices a chorus of bassoons, cellos, and bass viols.

Marna had lived for two centuries because Tyr had begged her to, and her only grief at her own impending death was that she could not return to Riya. It was the tinerals that worried her, the tinerals and the need to continue the warning. She had long since set a verbal warning broadcast on every communication band known to the R'il'nai. The language was inherited; other R'il'nai—if there were any—would still be warned off, but with no one to answer their questions. And surely there were others! The population of R'il'n had broken up into several groups during the diaspora, when the astronomers had predicted that their home would become unlivable in a few millennia. Surely one of the other groups had found a world as welcoming as Riya, and survived!

She could supplement the audio warnings with the visuals from the last days of the dying, and with a mental recording sent out via mechanical telepathy. It wouldn't be as good as her own direct communication, but she couldn't think of anything more she could do.

The tinerals, though ... She traversed a tunnel that looked like a paneled corridor, followed by a group of the hungry animals, and entered a smaller dome. The vegetation here was grain, fruit bushes and vegetables, robot tended. Most of the plants were drooping or covered with masses of fungal spores, though in one corner insects shrilled. Marna wrinkled her nose in disgust at the sour, musty smell. It didn't help that she had to breathe deeply to compensate for the reduced oxygen and excess carbon dioxide in the air.
Would it have made a difference, she wondered, if she had checked the computer, perhaps taken it out of the system entirely half a year ago, instead of trying to deal with each biological emergency that arose in the way she understood, as a Healer? "Not likely," she muttered to herself as she crossed the bridge over an artificial stream. The water was opaque with algae and bacteria, and added its own foul stench to the air.

Two or three varieties of the ornamental plants surrounding the food culture building were thriving, but they were all species too toxic to use as food. Too poisonous even for the fungi, bacteria, and insects, she thought.
She'd switched to thermally distilled water for the food culture vats several months ago, but it hadn't stopped infections entirely. She'd had to destroy all but two of the cultures, and neither of the survivors smelled or tasted normal. The tinerals, whose official function had been to alert her to problems with food or water, refused one entirely and would barely nibble at the other. The group that had followed her and that now clustered just outside the door to the building were attenuated with near starvation, but when she offered them a bowl of the least suspect culture only the youngest would even try it.

"Well, the distilled water's still drinkable," she told them as she filled a second bowl. The tinerals drank so eagerly that they must have entirely stopped using the fouled streams. The still's capacity would barely support her, the surviving cultures, and the fifty or so animals.

Marna took a sample of the less contaminated culture and determined that it was not actually toxic, then dumped a glob into the cooker and set it to produce a highly spiced stew. She wouldn't have chosen the dish normally, but she hoped the seasoning would disguise the foul taste the culture had developed. She laid eating tongs and a bulb of chilled water on a lap tray, noting as she did that the group of tinerals at the door had swelled to over thirty, with more coming across the dying fields. She refilled the water bowl they had emptied. This must be their only remaining source of food and water.

So what was she going to do about them? They had been widespread as pets on Riya, domesticated for so long that even their planet of origin had been forgotten. She had encouraged hers to forage for part of their food, but on the satellite they had no competitors and no predators. The pathogens that were destroying her artificial ecosystem were common on the planet, so she didn't need to worry about contaminating Riya. She could teleport the tinerals home, or could she? It had been two centuries since she had teleported a living creature. Better pull up some of the computer's information on teleporting. She did remember that all kinds of conservation laws were involved.

"Well, you certainly can't survive much longer here," she told them as she added the completed spiced stew to her tray and carried her lunch to a bench outside the door. Two juveniles—the brilliant green male she called Emerald and a soft orange female, Citrine—fluttered down beside her and begged for food, crouching on their folded hindquarters and reaching their hands out in entreaty. She offered them a chunk from the stew and watched their reactions. Emerald sniffed, looked at her beseechingly, sniffed at her bowl as if to reassure himself that this was indeed what she was eating, and took a tentative nibble. After two bites, he allowed Citrine to grab the rest of the chunk. The orange tineral went through the same pantomime before dropping the remainder of the chunk to the ground. No, they couldn't survive here.

"The big problem is predators," she told them thoughtfully. "Maybe one of the vacation islands, where the predators were exterminated?" Against her will, her mind returned to a summer two hundred years gone, and the subtropical island called Windhome. She'd met Win there, a Healer like herself. He slid into her memory—violet eyes, hair so darkly red it was almost black, and a bronzed face alight with laughter or tender with love. She'd been flying through the tunnel of a breaking wave when it had collapsed on her, and Win had TK'ed her out of danger. Later they'd flown together, levitating through surf and over mountains, and made love in a hidden valley dizzy with flowers. They'd planned to rear a child together when Marna finished her research. She'd touched minds with Win often, in the early days of the epidemic, and later done her best to lighten his agony as he himself lay dying. He had been as insistent as Tyr that she not return.

She pushed the memory away, forcing herself to think only of the possibility that Windhome might be a suitable place for the tinerals. Win would approve, she thought as she carried her tray back inside the building. He had given her the four tinerals from whom the population of the satellite descended, and convinced the rather dubious medical council to let her take them with her. She could still see him, his face carefully arranged to solemnity for the benefit of the council, explaining how the animals could serve as a check on the food and water recycling systems. He'd never argued that with her, stressing instead the company they would be. Well, he'd been right both ways.

The computer's communication link to the big planetary monitor on Riya was still intact, and appeared so far to be working normally. Marna walked through empty rooms to the nearest interface and pulled up the planetary computer. She identified herself—silly, she thought, since there isn't anyone else to contact it. she entered.
\Reason for request?\ the computer responded.

Drat your programming, she thought.

The computer's silence lasted considerably longer than the light speed transmission time to Riya and back. \My condolences\ it finally replied. \The station computer has lost control over that section. The life support programming appears to have broken down completely. I suggest you send your completed message back to this facility for broadcast in case there are further breakdowns. Videos are being transmitted on alternate channel.\

That made sense, Marna thought. Now for the next problem. The computer responded promptly, and Marna's eyes widened as she looked at all the information. That complicated? She remembered the requirements for energy and momentum balance, but the computer was practically giving her a short course in physics!

She'd known this once, and she could learn it again fairly quickly, but she had over fifty tinerals to teleport, and only a few days to do it in. Exchange teleports were easy, she remembered. Exchanging two objects with the same mass, size and shape automatically balanced energy and momentum. Under normal circumstances she would not have considered bringing anything from the surface up to her isolated satellite, but given the state of the artificial ecosystem that was hardly a problem. But what could she find that was the same size, shape and density as a tineral?

Chewing on a broken fingernail, she brought up the material on exchange teleports, and found that was exactly the problem with simple exchange teleports—sea water and a little air would work as an exchange medium, but the tinerals would wind up in the water, and they were terrible swimmers. Most would drown.
"There's got to be a simple answer," she muttered, and noticed a link to multiple exchange teleports. She absorbed the new information, and suddenly saw a solution. "A triangular exchange," she said aloud. "Take the air out of the volume I'm 'porting you into, put it in the ocean, and teleport the water up here to balance your mass. It won't be exact, but I can add some energy to make the potential energy balance. It won't be any harder than lifting one of you. You might get splashed when the water rushes in to replace the air, but it should work without drowning you." Ruby chirped questioningly from the arm of her chair.

"I've got a new home for you, where there's plenty of food and good water. I might even be able to find you some new friends," she told the three who'd followed her into the building.

It took four days to teleport all of the tinerals except Ruby, Emerald and Citrine to Windhome and to complete her recorded warning. She had already set the station computer to broadcast her message for as long as the power panels would hold out—perhaps for centuries—and the source code for the recorded warning was now being transmitted to the planetary computer on Riya. The air had gotten so bad that she kept an oxygen tank—the last one—by her side. The last culture had tested as too toxic to risk eating three days ago, and she had only one packet of preserved food left.

Ruby and the two youngsters were gasping and struggling for air, and she gave them each a few breaths from the oxygen tank, and then filled her own lungs. "Time for you three to go," she told them, trying to keep her voice calm. "I won't be able to manage a teleport if we wait any longer."

Ruby cried in protest, clinging to Marna's neck when she was picked up, and Marna's careful calm deserted her. "Ruby, you can't live here any more," she sobbed. "And I can't leave. I promised. Tyr and Win both. That I'd stay here and warn people not to land."

Use your head, girl. Your job was to provide a warning. You can't do that if you die here. It's time to come home, love.

Win? she thought wildly. Of course it couldn't be; lack of food and oxygen were making her woozy. She took a few more deep breaths of oxygen. Not Win, but her own subconscious. She'd conditioned herself so thoroughly to her own exile that she hadn't seen that it had become totally meaningless. And the same triangular exchange teleport that she had used with the tinerals should work for her.

"Home," she said aloud. "I can go home. I may die, but I'll die with a Riyan wind in my hair." She ripped open the food packet with shaking hands, slung the carrying strap of the oxygen tank over her shoulder, and picked up Ruby and a bulb of water. Emerald and Citrine fluttered to her shoulders. Eating and drinking as she went, Marna ran back to her sleeping quarters. A change of clothing and a portable interface went into her carrysack, followed by an ultra light sleeping bag and a tri-dee of Win. She closed her eyes briefly as she picked up the hair clasp he had given her. A woman trying for a baby let her hair grow out; the clasp had been a promise of the child they had planned. She'd never worn it. She thrust it into the sack and glanced around the room for one last time. Nothing else here of importance but printouts of the breeding records of the tinerals, and she'd be able to access them from the planetary computer on Riya.

Marna took a final deep breath from the oxygen tank and wrapped her mind around the three tinerals and the carrysack. She let Windhome flood into her consciousness: the smell of the breeze caressing her face, the sun bright overhead—no, it was sunset there now, with high bands of cirrus glowing pink against the rapidly darkening sky and surf breaking on the amethyst beaches. Her memories coincided with reality, and she pushed herself through into the warm summer evening.

The plague that had destroyed her world might yet lurk in the green-scented air, but if it did, she welcomed it. A rush of tinerals surrounded her. "Home," she said again. "I'm home."