We wore gloves, except that I kept removing mine because it interfered with the work. Then my hands would turn to ice, and I'd put them back on to warm up before taking another stab at attaching the fine filaments that ran microvolts to the plasma globules.

Suddenly, the air-pressure sensor started screaming its fool head off. Arlene and I exchanged a worried glance, but we didn't need to be told twice. It was time to start hitting the raw stuff, O2 neat. We took hits off the same oxygen bottle, trying to limit ourselves to a few breaths every hour or so, or when we started to get dizzy or goofy.

But we just didn't have that much bottled oxygen.

Uncle Sugar packed a lot of air into a single bottle; but even so, even at the slow pace we used it, we'd run out of breathing oxygen in just a few more days. We had more bottles, but we needed them for fuel mixing.

And of course we'd need to breathe more frequently as the pressure dropped-paradoxically, it was drop- ping slower now, since there was less pressure in the dome to push the air out.

We stretched the bottles as long as we could, but they ran out while there was still plenty of work left.

I'd done mountain climbing in my native Colorado before joining the Corps; as the air grew thinner, I tried to help Arlene deal with it. "Breathe shallowly,"

I said. "Rest, and don't talk except for the job."

The physical exertion wasn't any less, though. We'd have to stop frequently, gasping and panting. We tired easily and needed more sleep, but stayed on the four- hour rotations, creating a cycle of exhaustion we couldn't break. But sleeping longer would just make the job take longer, and the pressure would drop lower in the meantime.

Low pressure is insidious. There are obvious ef- fects: exhaustion, trouble breathing, and cold. But there are other symptoms people don't often think about: your ears ring; it's hard to hear sounds (thinner air makes everything sound m.u.f.fled and "tinny"); and worst of all, your mind can start to go. Our brains are built for a certain barometric pressure, and if it's too high or too low, we start getting strange.

Or in Arlene's case, hallucinogenic.

"Pumpkin!" she suddenly screamed, waking me after two hours of my allotted four. She grabbed a b.u.mp-action riot gun and pounded a shot over myhead, so close it made my skull vibrate.

"Pumpkin" was our name for the horrible, floating alien heads-mechanical, I think-that vomited ball lightning capable of frying you at fifty paces. I threw myself off the table we used as a bed, figuring the vacation was over: the aliens had found us at last!

But when I dropped to my knees, Sig-Cow rifle at the ready, all I saw was the dark hole in the wall left by my overly enthusiastic motor test of a week ago.

Arlene ran down the pa.s.sageway ahead of me, firing wildly; firing at nothing. But those b.a.s.t.a.r.d alien "demons" could be fast! I had no reason to doubt my buddy as I joined her, ready to do what we'd done countless times during our a.s.sault on Phobos, Deimos, and the tunnel.

Then she ran straight into the bulkhead like it wasn't there, and I suddenly realized something was seriously wrong with her.

She knocked herself out. I couldn't look after her then; I had to make sure about the pumpkin.

Knuckling the residue of sleep from bloodshot eyes, I ran like a mother down the corridor, eyes left, right . . . not wasting a shot but ready for the enemy. For an instant I thought I saw a flying globe and almost squeezed off a shot. But it was a trick of peripheral vision, just a flash of my own shadow.

A cul-de-sac at the end of the corridor finally convinced me that there was no freaking pumpkin.

I stood for a moment, desperately trying to get nonexistent air into my burning lungs. Then I re- turned to Arlene, who groaned and panted as she started coming to.

"Pal, honey, I hate to do this . . . but I've got to relieve you of your weapon."

She stared uncomprehendingly.

"There was no pumpkin," I explained. "You're suffering from low-pressure psychosis."

"Oh Jesus," she said quietly. She understood.

Sadly, she handed over the scattergun and her AB-10 machine pistol.

I felt like the bottom of my boots after walking through the green sludge. You don't relieve a Marine of his weapon, not ever. By doing so, I'd just effec- tively demoted her to civilian. And the worst part was, even she realized now that she'd been halluci- nating.

She was crying when we walked slowly back to the vehicle a.s.sembly room, a.k.a. the hangar. I'd never seen Arlene cry before-except when she had to kill the reworked, reanimated body of her former lover, Dodd.

"Hey," I said a few hours later, "can't we electro- lyze water and get oxygen?"

Arlene was silent for a moment, her lips moving.

"Yes," she said, "but we'd only get a few breaths per liter, and we need the water too, Fly."

"Oh." Not for the first time, I wished I knew more engineering. I vowed to take cla.s.ses when we made it back home ... if there even was a "back home"

anymore.I started having unpleasant dreams, so I didn't mind giving up more of my sleep allotment. It was always the same dream, actually. I loved roller coast- ers as a kid. They were the closest I could get to flying in those days. I lived only five miles away from a freestanding wood-frame monster. I thought I would love nothing better, until they built a tubular steel, eight-loop supercoaster.

I'd never been afraid on the old roller coaster. With all the courage of an experienced ten-year-old, I'd sit in the car as it slowly reached the top, the horizon slanting off to my left, and pretend it was the rim of a planet and I was an astronaut. As it went over the top, plunging down a cliff of wood and metal, I made it a point of honor not to hold on to the crash bar. I was too grown-up for that!

I was always interested in how things were put together and how they worked. So I asked about the new roller coaster. A man who worked at the amuse- ment park told me stuff he wasn't supposed to say, stuff he knew nothing about-about how the forces generated could snap a human neck like rotten cord- wood, how the auxiliary chain that gave the car acceleration had a lot of extra strain on it for an eight- loop ride.

As I started up the first hill of the new ride, I thought about what I'd learned. I didn't know it was all bogus c.r.a.p made up to impress a ten-year-old.

The first loop, I worried about centrifugal force snapping my neck; the second loop, I sweated over velocity tearing me out of my seat; the third loop, I fixated on the d.a.m.ned chain coming loose; and the fourth loop was reserved for a ten-year-old having ulcers over the gears stripping. And then I threw up- not a good thing to do when you're upside down.

I wonder if that b.a.s.t.a.r.d ever knew what damage his misinformation caused?

As I grew up, I learned how real knowledge could banish fear. You play the odds. You focus on the job at hand. You don't want to mess up. The childhood trauma was behind me ... until it came back now on Deimos as I tried to grab a little sleep. Instead of rest, I was back on that eight-loop metal monster, and now it turned into the arms and legs of a steam-demon.

When the creature screamed at me and raised its missile arm, I would always wake up; so I didn't even have the pleasure of fighting or dying.

I didn't worry about my stupid dreams, though. It sure beat fighting the real thing. Besides, I was getting off easy compared to Arlene.

I knew things were bad when I tried to wake her up and she stared with unblinking eyes, not seeing a d.a.m.ned thing. I realized she was still asleep. I'd read somewhere that it's risky to wake a person from a trance state, and I didn't require medical training to know Arlene was Somnambulist City.

There wasn't time to go hunting for a medical library. A quick check of medical supplies produced a Law Book, wedged between the surgical bandages and antibiotics. I had to laugh. A text on medical malprac-tice had made it all the way to a Martian moon, and now, by way of a hypers.p.a.ce tunnel, had almost returned to Earth.

I wasn't laughing as I returned to Arlene. She walked in her sleep, striking at the air in front of her.

"Get away," she said to phantoms only she could see.

"I won't leave you. I'll stay, I'll stay!"

5.

If I shouldn't wake her, there seemed no reason I shouldn't try to communicate. "Arlene, can you hear me?"

"Quiet," she said, "I don't want Fly to hear you.

He's depending on me."

"Why don't you want him to know about me?" I asked.

"Because you're evil," she said with conviction.

"You're all evil, you b.a.s.t.a.r.ds."

She walked slowly down the corridor. So long as she wasn't in danger of hurting herself, I saw no reason to shock her out of it. "Why are we bad?"

"You scare me. You make my brother do bad things!"

Up to that point I did not know that Arlene even had a brother.

It was weird-I thought we'd known everything about each other's family life. She talked about her parents and growing up in Los Angeles all the time. I was uncomfortable pursuing the matter, but I rationa- lized away my moral qualms and decided to play out the hand. "Who are we?" I asked again.

She swayed drunkenly, delivering a monologue like those weird, old plays from previous centuries. "Bad things in the air, in the night, making my brother crazy. He'd never do bad things except for you. I thought I'd never see you again . . . Why'd you follow me into s.p.a.ce, to Mars, to Deimos? When I grew up, I thought you weren't real, but now I know better. You followed me, but I won't let you get inside me; not inside!"

When Arlene had kidded me about going down memory lane, I took it in good humor. But if we were going to have to relive all the bad stuff from our childhood as the air leaked away, I was good and ready to say good-bye to Deimos now, rocket or no rocket, instead of later.

In the meantime, what was I going to do about Arlene? I couldn't let her wander the corridors, argu- ing with ghosts from her childhood. With time short and no way to send to Earth for a correspondence course in psychology, I went with common sense.

"Arlene, we'll make a deal with you," I said. "We'll stop bothering you and let you get back to Fly."

"In exchange for what?" she wanted to know, quite reasonably.

"Because we've moved back to Earth, and you can't touch us there."

"Fly and I are building a ship to take us to Earth,"

"Ha, we don't believe you two will get anywhere near us. You'll be stuck on Deimos forever!"

"That's a lie!" she snapped, and stopped walking."We'll fight you again." She stared right at me. "We're not afraid of your little genetic stupidmen."

"Big words!" I said.

She came right at me, fists raised, and started hitting me. As I fended off her blows-not too difficult, considering the difference in reach-I yelled, "Hang on, Arlene, I'm coming to help you.

This is Fly, Fly!"

As I say, I never took any courses in psychology, but I acted in school plays. And to steal a phrase, it doesn't take a rocket scientist to go with the flow. I gave myself a magna c.u.m laude graduation as her eyes came into focus and she recognized me.

"Fly? What happened?"

"We've been fighting monsters again."

She looked around the empty corridor and then back to me. I didn't have to spell it out. "How much longer can we take this?"

"Not a second longer than we have to."

Arlene started seeing weird colors after that- auras, shadows, and things she wouldn't tell at first.

Sometimes she would put the tech doc.u.ments down, sitting quietly with her eyes shut until the colors went away.

It scared me plenty, but it terrified her. She was losing her mind-and she knew it. So when I told her the engine was eighty percent finished, Arlene urged, "Fly, forget the other twenty percent. It's done! Let's blow this popcorn stand."

I had to be honest. "A.S., there are still a few systems I don't think are in really good shape."

"We can't wait. We've taken chances with worse odds than that the whole time we've been on this rock. Fly, I ... I stopped being able to see color vision this morning. All I can see is gray-except when I hallucinate a rainbow-colored aura. And my peripheral vision is shot." She paused, licking her lips. "And Fly, there's something else."

She came close and spoke softly, seriously. "I want to confess something to you, Fly. What would your nuns think of that? For the first time I'm really afraid.

I'm afraid I might kill you, thinking you're one of the monsters. I couldn't stand that."

The little voice in the back of my head had whis- pered that possibility when she first imagined the pumpkin. It was a chance I was willing to take. Even so, I was glad she, not I, stated the danger loud and clear.

I sped up preparations, insisting that Arlene sleep whenever possible. The air and pressure problems were getting to me as well, but I handled them better than Arlene.

Of course, the problem with oxygen starvation is that you are not the best judge of your own reason.

But the best chance for both of us was to finish the rocket.

And we were close, tantalizingly close.

I suddenly got the creepy crawlies. I recognized the symptom: I was picking up the same psychosis as Arlene. "All right," I acquiesced, "we go in the nextfew hours. We have a chance, I guess; eighty percent is eighty points better than zero."

We got busy. We drank water. We ate a last good meal of biscuits, cheese, fruit, nuts. The Eskimos say that food is sleep, by which I guess they mean if your body can't get one kind of recharge, you might as well take the other.

Arlene abandoned me to work out the telemetry program that would (G.o.d willing) launch us, kill Deimos's...o...b..tal velocity, dropping us into the atmos- phere, then take us down, at which point she'd hand over control to me to find a suitable spot to touch down. Fortunately, it was basically cut-and-paste; I doubt she could have written it from scratch . . . not in the condition she was in. The hand of G.o.d must have graced her, though she'd never admit it, for her to keep it together long enough to patch it together.

As we prepared to leave, I kept running the basic worries through my mind. The mail tubes were de- signed for Mars, which has only a fraction the atmos- phere of Earth and a much lower gravity; the specific impulse developed by the rockets might not be enough to overcome Earth's gravity as we spilled velocity and tried to land. On the other hand, the thick atmosphere might cause so much friction that our little ship would burn up.

The launcher was a superconducting rail gun. Re- minded me of the eight-loop wonder at the amuse- ment park back in the Midwest. This time I hoped I wouldn't throw up. At least this piece of equipment didn't have an auxiliary chain ... so what was there to worry about?

I grunted the launcher around to point opposite Deimos's...o...b..tal path. The rocket controls were sim- ple to operate, thank G.o.d; throttle, stick, various navigational gear that I didn't really understand, and environmental controls, all ranged around my face in a tremendously uncomfortable position.

Then suddenly, a few hours before our scheduled departure, Arlene totally freaked out.

At first I thought she was joking. She strolled up to me and said, "Don't try to fool me; I know what you really are."

"Yeah, a prize SOB," I said distractedly. A moment later I was on my b.u.t.t with Arlene's boot on my chest and a shiv-a sharpened piece of metal-against my throat. Looking into her eyes, I saw the blank look of a zombie . . . and for a moment, Jesus, I thought they'd somehow gotten her, reworked her!

But it was just the low pressure, or maybe slow oxygen deprivation. I talked to her for five minutes from my supine position, saying anything, G.o.d knows what, anything to snap her back to some semblance of herself. After a while she dropped the shiv and started crying, saying she had murdered G.o.d or some such silly nonsense.

I wasn't going to abandon her, no matter what; but there was nothing in my personal rule book that said I had to make it any more difficult. We had Medikits in the shed. I gave her a shot. She struggled, coughed,and turned to me. "Why can't we eat our brothers?"

she asked; then the drug took effect.