Mission Commander Stanley stared at the X-rays of his engine. It was four in the morning. There would be no more sleep for him that night; he was scheduled to fly to Washington at six to testify to Congress.

‘“Your decision, Commander,” the engine technician said.

“We can’t find any flaws in the X-rays we took of the flight engines, but it could be hidden. The nominal flight profile doesn’t take the engines to a hundred twenty, so the blades should hold even if there is a flaw.”

“How long a delay if we yank the engines for inspection?”

“Assuming they’re okay, we lose a day. If not, two, maybe three.”

Commander Stanley drummed his fingers in irritation. He hated to be forced into hasty decisions. “Normal procedure would be?”

“Normally we’d want to reinspect.

“Do it.”

He sighed. Another delay. Somewhere up there, somebody was counting on him to get there on time. If she was still alive. If the cut-off radio signal didn’t signify catastrophic failure of other systems.

If she could find a way to survive without air.

On Earth it would have been a marathon pace. On the moon it was an easy lope. After ten miles the trek fell into an easy rhythm: half a walk, half like jogging, and half bounding like a slow-motion kangaroo. Her worst enemy was boredom.

Her comrades at the academy—in part envious of the top scores that had made her the first of their class picked for a mission—had ribbed her mercilessly about flying a mission that would come within a few kilometers of the moon without landing. Now she had a chance to see more of the moon up close than anybody in history. She wondered what her classmates were thinking now. She would have a tale to tell—if only she could survive to tell it.

The warble of the low voltage warning broke her out of her reverie. She checked her running display as she started down the maintenance checklist. Elapsed EVA time, eight point three hours. System functions, nominal, except that the solar array current was way below norm. In a few moments she found the trouble: a thin layer of dust on her solar array. Not a serious problem; it could be brushed off. If she couldn’t find a pace that would avoid kicking dust on the arrays, then she would have to break every few hours to housekeep. She rechecked the array and continued on.

With the sun unmoving ahead of her and nothing but the hypnotically blue crescent of the slowly rotating Earth creeping imperceptibly off the horizon, her attention wandered. Moonshadow had been tagged as an easy mission, a low-orbit mapping flight to scout sites for the future moonbase. Moonshadow had never been intended to land, not on the moon, not anywhere.

She’d landed it anyway; she’d had to.

Walking west across the barren plain, Trish had nightmares of blood and falling, Sanjiv dying beside her; Theresa already dead in the lab module; the moon looming huge, spinning at a crazy angle in the viewports. Stop the spin, aim for the terminator at low sun angles, the illumination makes it easier to see the roughness of the surface. Conserve fuel, but remember to blow the tanks an instant before you hit to avoid explosion.

That was over. Concentrate on the present. One foot in front of the other. Again. Again.

The undervoltage alarm chimed again. Dust, already?

She looked down at her navigation aid and realized with a shock that she had walked a hundred and fifty kilometers.

Time for a break anyway. She sat down on a boulder, fetched a snack-pack out of her carryall, and set a timer for fifteen minutes. The airtight quick-seal on the food pack was designed to mate to the matching port in the lower part of her faceplate. lt would be important to keep the seal free of grit. She verified the vacuum seal twice before opening the pack into the suit, then pushed the food bar in so she could turn her head and gnaw off pieces. The bar was hard and slightly sweet.

She looked west across the gently rolling plain. The horizon looked flat, unreal; a painted backdrop barely out of reach. On the moon, it should be easy to keep up a pace of fifteen or even twenty miles an hour-counting time out for sleep, maybe ten. She could walk a long, long way.

Karen would have liked it; she’d always liked hiking in desolate areas. “Quite pretty, in its own way, isn’t it, Sis?’’ Trish said. “Who’d have thought there were so many shadings of grey? Plenty of uncrowded beach. Too bad it’s such a long walk to the water.”

Time to move on. She continued on across terrain that was generally flat, although everywhere pocked with craters of every size. The moon is surprisingly flat; only one percent of the surface has a slope of more than fifteen degrees. The small hills she bounded over easily; the few larger ones she detoured around. In the low gravity this posed no real problem to walking. She walked on. She didn’t feel tired, but when she checked her readout and realized that she had been walking for twenty hours, she forced herself to stop.

Sleeping was a problem. The solar arrays were designed to be detached from the suit for easy servicing, but had no provision to power the life-support while detached. Eventually she found a way to stretch the short cable out far enough to allow her to prop up the array next to her so she could lie down without disconnecting the power. She would have to be careful not to roll over. That done, she found she couldn’t sleep. After a time she lapsed into a fitful doze, dreaming not of the Moonshadow as she’d expected, but of her sister, Karen, who—in the dream—wasn’t dead at all, but had only been playing a joke on her, pretending to die.

She awoke disoriented, muscles aching, then suddenly remembered where she was. The Earth was a full handspan above the horizon. She got up, yawned, and jogged west across the gunpowder-grey sandscape.

Her feet were tender where the boots rubbed. She varied her pace, changing from jogging to skipping to a kangaroo bounce. It helped some; not enough. She could feel her feet starting to blister, but knew that there was no way to take off her boots to tend, or even examine, her feet.

Karen had made her hike on blistered feet, and had had no patience with complaints or slacking off. She should have broken her boots in before the hike. In the one-sixth gee, at least the pain was bearable.

After a while her feet simply got numb.

Small craters she bounded over; larger ones she detoured around; larger ones yet she simply climbed across. West of Mare Smythii she entered a badlands and the terrain got bumpy. She had to slow down. The downhill slopes were in full sun, but the crater bottoms and valleys were still in shadow.

Her blisters broke, the pain a shrill and discordant singing in her boots. She bit her lip to keep herself from crying and continued on. Another few hundred kilometers and she was in Mare Spumans—“Sea of Froth”—and it was clear trekking again. Across Spumans, then into the north lobe of Fecundity and through to Tranquility. Somewhere around the sixth day of her trek she must have passed Tranquility Base; she carefully scanned for it on the horizon as she traveled but didn’t see anything. By her best guess she missed it by several hundred kilometers; she was already deviating toward the north, aiming for a pass just north of the crater Julius Caesar into Mare Vaporum to avoid the mountains. The ancient landing stage would have been too small to spot unless she’d almost walked right over it.

“Figures,” she said. “Come all this way, and the only tourist attraction in a hundred miles is closed. That’s the way things always seem to turn out, eh, Sis?”

There was nobody to laugh at her witticism, so after a moment she laughed at it herself.

Wake up from confused dreams to black sky and motionless sunlight, yawn, and start walking before you’re completely awake. Sip on the insipid warm water, trying not to think about what it’s recycled from. Break, cleaning your solar arrays, your life, with exquisite care. Walk. Break. Sleep again, the sun nailed to the sky in the same position it was in when you awoke. Next day do it all over. And again. And again.