And, indeed, it was slow going. She couldn’t bound down slopes as she used to, or the broken strut would fail and she’d have to stop for painstaking repair. There were no more level plains; it all seemed to be either boulder fields, crater walls, or mountains. On the eighteenth day she came to a huge natural arch. It towered over her head, and she gazed up at it in awe, wondering how such a structure could have been formed on the moon.

“Not by wind, that’s for sure,” said Karen. “Lava, I’d figure. Melted through a ridge and flowed on, leaving the bole; then over the eons micrometeoroid bombardment ground off the rough edges. Pretty, though, isn’t it?”

“Magnificent.”

Not far past the arch she entered a forest of needle-thin crystals. At first they were small, breaking like glass under her feet, but then they soared above her, six-sided spires and minarets in fantastic colors. She picked her way in silence between them, bedazzled by the forest of light sparkling between the sapphire spires. The crystal jungle finally thinned out and was replaced by giant crystal boulders, glistening iridescent in the sun. Emeralds? Diamonds?

“I don’t know, kid. But they’re in our way. I’ll be glad when they’re behind us.”

And after a while the glistening boulders thinned out as well, until there were only a scattered few glints of color on the slopes of the hills beside her, and then at last the rocks were just rocks, craggy and pitted.

Crater Daedalus, the middle of the lunar farside. There was no celebration this time. The sun had long ago stopped its lazy rise, and was imperceptibly dropping toward the horizon ahead of them.

“It’s a race against the sun, kid, and the sun ain’t making any stops to rest. You’re losing ground.”

“I’m tired. Can’t you see I’m tired? I think I’m sick. I hurt all over. Get off my case. Let me rest. Just a few more minutes? Please?”

“You can rest when you’re dead.” Karen laughed in a strangled, high-pitched voice. Trish suddenly realized that she was on the edge of hysteria. Abruptly she stopped laughing. “Get a move on, kid. Move!”

The lunar surface passed under her, an irregular grey treadmill.

Hard work and good intentions couldn’t disguise the fact that the sun was gaining. Every day when she woke up the sun was a little lower down ahead of her, shining a little more directly in her eyes.

Ahead of her, in the glare of the sun she could see an oasis, a tiny island of grass and trees in the lifeless desert. She could already hear the croaking of frogs: braap, braap, BRAAP!

No. That was no oasis; that was the sound of a malfunction alarm. She stopped, disoriented. Overheating. The suit air conditioning had broken down. It took her half a day to find the clogged coolant valve and another three hours soaked in sweat to find a way to unclog it without letting the precious liquid vent to space. The sun sank another handspan toward the horizon.

The sun was directly in her face now. Shadows of the rocks stretched toward her like hungry tentacles, even the smallest looking hungry and mean. Karen was walking beside her again, but now she was silent, sullen.

‘“Why won’t you talk to me? Did I do something? Did I say something wrong? Tell me.”

“I’m not here, little sister, I’m dead. I think it’s about time you faced up to that.”

“Don’t say that. You can’t be dead.”

“You have an idealized picture of me in your mind. Let me go. Let me go!”

“I can’t. Don’t go. Hey—do you remember the time we saved up all our allowances for a year so we could buy a horse? And we found a stray kitten that was real sick, and we took the shoebox full of our allowance and the kitten to the vet, and he fixed the kitten but wouldn’t take any money?”

“Yeah, I remember. But somehow we still never managed to save enough for a horse.” Karen sighed. “Do you think it was easy growing up with a bratty little sister dogging my footsteps, trying to imitate everything I did?”

“I wasn’t either bratty.”

“You were too.”

“No, I wasn’t. I adored you.” Did she? “I worshipped you.”

“I know you did. Let me tell you, kid, that didn’t make it any easier. Do you think it was easy being worshipped? Having to be a paragon all the time? Christ, all through high school, when I wanted to get high, I had to sneak away and do it in private, or else I knew my damn kid sister would be doing it too.”

“You didn’t. You never.”

“Grow up, kid. Damn right I did. You were always right behind me. Everything I did, I knew you’d be right there doing it next. I had to struggle like hell to keep ahead of you, and you, damn you, followed effortlessly. You were smarter than me—you know that, don’t you?—and how do you think that made me feel?”

‘“Well, what about me? Do you think it was easy for me? Growing up with a dead sister—everything I did, it was ‘Too bad you can’t be more like Karen’ and ‘Karen wouldn’t have done it that way’ and ‘If only Karen had. . . .’ How do you think that made me feel, huh? You had it easy—I was the one who had to live up to the standards of a goddamn angel.”

“Tough breaks, kid. Better than being dead.”

“Damn it, Karen, I loved you. I love you. Why did you have to go away?”

“I know that, kid. I couldn’t help it. I’m sorry. I love you too, but I have to go. Can you let me go? Can you just be yourself now, and stop trying to be me?”

“I’ll . . . I’ll try.”

“Goodbye, little sister,”

“Goodbye, Karen.”

She was alone in the settling shadows on an empty, rugged plain. Ahead of her, the sun was barely kissing the ridgetops. The dust she kicked up was behaving strangely; rather than falling to the ground, it would hover half a meter off the ground. She puzzled over the effect, then saw that all around her, dust was silently rising off the ground. For a moment she thought it was another hallucination, but then realized it was some kind of electrostatic charging effect. She moved forward again through the rising fog of moondust. The sun reddened, and the sky turned a deep purple.

The darkness came at her like a demon. Behind her only the tips of mountains were illuminated, the bases disappearing into shadow. The ground ahead of her was covered with pools of ink that she had to pick her way around. Her radio locator was turned on, but receiving only static. It could only pick up the locator beacon from the Moonshadow if she got in line of sight of the crash site. She must be nearly there, but none of the landscape looked even slightly familiar. Ahead was that the ridge she’d climbed to radio Earth? She couldn’t tell. She climbed it, but didn’t see the blue marble. The next one?

The darkness had spread up to her knees. She kept tripping over rocks invisible in the dark. Her footsteps struck sparks from the rocks, and behind her footprints glowed faintly. Triboluminescent glow, she thought nobody has ever seen that before. She couldn’t die now, not so close. But the darkness wouldn’t wait. All around her the darkness lay like an unsuspected ocean, rocks sticking up out of the tidepools into the dying sunlight. The undervoltage alarm began to warble as the rising tide of darkness reached her solar array. The crash site had to be around here somewhere, it had to. Maybe the locator beacon was broken? She climbed up a ridge and into the light, looking around desperately for clues. Shouldn’t there have been a rescue mission by now?

Only the mountaintops were in the light. She aimed for the nearest and tallest mountain she could see and made her way across the darkness to it, stumbling and crawling in the ocean of ink, at last pulling herself into the light like a swimmer gasping for air. She huddled on her rocky island, desperate as the tide of darkness slowly rose about her. Where were they? Where were they?