Mars Crossing

1 Leaving Africa

The glow of sunset lasted far after the sun disappeared. The sky turned a deep, brick red, and the red faded until it was almost invisible. Two stars in the west, a brilliant blue-white one and a smaller one of tarnished silver next to it, were the Earth and the moon.

And then it was dark.

For some reason the hazy darkness reminded Radkowski of his last night in Africa. Sunset fell quickly in Africa, not like here on Mars, and on that night Venus has shone brilliant in the west.

His flying comrades had thrown a going-away party that night. It was partly for him, but more than that, it had been a party for dead comrades who had not returned from the disaster of the last mission.

They had lit torches, and they glowed like votive candles, forlorn hopes against the hot, sullen night. Two of the fliers had guitars, and they had set up amplifiers and played with an almost palpable violence, trying to cover up the badness of their playing by sheer intensity of sound.

They partied desperately. They were in a dead-end war, and they knew it. He walked through the party like a dead man, not talking, not acknowledging anyone, numb, his mangled hand hurting. He was already separate from the group. To them, he was already on his way home.

The party had gone on late into the morning, long after he had left it to collapse in his bunk, too drunk to move, too drunk to care any more.

The Mars night was, really, nothing like that, except that he was alone, and the night was dark.

I’m a hundred million miles away from that now, he thought. I have left it all behind.

But John Radkowski knew that he could never, really, leave it all behind.

Injured or not, tomorrow they would move on.

2 Onward

The dirt-rover that Estrela had been riding had not been badly damaged, and any shop on Earth could have straightened the bent frame, replaced the smashed wheel bearings, and put it back in working condition in a few hours. With neither a machine shop nor parts, though, Ryan said that it was out for the duration.

They loaded it on the rockhopper to use for spare parts to keep the second dirt-rover running.

The Mars suits were form-fitting, and once Tana had cut the suit off of Estrela, her arm and ankle had both started to swell. It looked like she was wearing a balloon around her ankle now.

Estrela’s damage turned out to be a fractured left radius, a dislocated left shoulder, and a mildly sprained ankle. Possibly with torn ligaments, Tana said, although it was hard to tell without X rays. In any case, it was lucky that she had not been hurt worse. Tana worked calmly and quickly, without thinking beyond what needed to be done at the moment; it was what she did best. She immobilized the arm with an inflatable, and while the balloon held it in place, mixed up a liquid polymer to set it in a more durable cast. With the broken bone set, she relocated the shoulder and strapped it to Estrela’s side to keep her from reinjuring it. She wrapped the ankle and instructed Estrela not to put weight on it, and finally, with the acute problems solved, made a more thorough examination. And only then, when she had verified that none of the other minor bruises masked deeper injuries, did she allow herself to think. An idiot, she thought. What the hell had Estrela thought she was doing?

They had brought along a supply of the piezoelectric fabric, and while they were camped, Ryan spliced a gore of spare material to replace the part of the spacesuit destroyed when Tana had cut it away. It was slow and painstaking work. Each square centimeter of fabric required ten electrical connections to be spliced to the computer that controlled the suit’s tension.

He worked on it for several hours. “I think that this will do it,” he said at last. He held out the arm of Estrela’s Mars suit, flexing it this way and that and watching the seam with a critical eye. “You might have been a little more careful about slicing this thing—you don’t want to know what this suit material costs per square centimeter.”

“She’s not going to put on a suit for a while,” Tana said.

“Better to have it ready now for when she needs it later,” Ryan said. “But next time, peel it away instead of cutting it, okay?”

It was fortunate, Ryan thought, that Tana had had the presence of mind to insist that Estrela be taken to the rover for treatment, and not put in the bubble habitat. If she had cut away Estrela’s suit in the habitat bubble, they would have had to stay where they were until she could put on her suit again; there was no way to get her out of the bubble with no suit. But in the pressurized cabin of the rover, they could resume their journey as soon as they were ready.

Ryan was ready to rig up the block and tackle to take the rockhopper down the cliff the next morning, but that turned out not to be necessary. It was not much of a cliff, a minor upthrust fault, more of a step in the ground level than a real obstacle to their travel. Commander Radkowski walked the territory, and then directed the rockhopper along the edge for a little ways to a place where the height was low enough that the rockhopper was able to simply step down, the articulated struts dropping one wheel down at a time. Once on the bottom, he picked up the remaining dirt-rover with the rockhopper’s robotic arm and lifted it down the cliff.

Commander Radkowski directed Ryan to take the dirt-rover ahead to scout, but cautioned him to stay in direct line of sight of the rockhopper. Trevor, now perched in Tana’s spot on the top, was given the binoculars, and was told to keep scanning ahead for any additional bad terrain, and to radio warnings ahead to Ryan as he saw fit.

There were several more small cliffs, all of them running east to west, perpendicular to their line of travel. In each case, Trevor was able to spot a place where the wall had slumped, or where a pile of rocks made a natural ramp for the vehicles to continue on. None of these was a significant obstacle.

As it turned out, the next obstacle was more than just a small escarpment. It was a canyon.

3 The Lesser Grand Canyon

Ryan parked ten meters or so back from the edge of the canyon and dismounted to look at it. Trevor jumped off the top of the rockhopper and walked over and past him to look over the edge. “Shit,” Trevor said. “This is incredible.”

“Stand a little further back, kid,” Ryan said. “We don’t know how stable this edge is.”

The canyon was so wide that the opposite wall was misty in the distance. The edges were fluted. Looking down, it was a dizzying drop to an incline of broken rock fragments, the talus slope. Ryan Martin got down on his belly and looked over the edge. It was an absolutely vertical drop, maybe two hundred meters straight, before the rubble at the bottom began to slope outward. The wall looked layered, but it was pretty hard to tell from this angle.

In both directions, the canyon extended out as far as they could see, disappearing in the distance.

“Wow,” Trevor said. “I never thought that Valles Marineris would be so spectacular. It’s like the Grand Canyon.”

Ryan looked at him for a moment, and laughed.

“I don’t get it,” Trevor said. “What’s funny?”

“You think this one is impressive?” Ryan shook his head. “Kid, we’ve still got a long way yet before we get to the big one. This isn’t the Valles Marineris. Just the appetizer.”

“Does it have a name?”

Commander Radkowski had exited the rockhopper and was now standing beside them. “Coprates Catena,” he said. “We’re getting close to the Valles Marineris territory; this is just a groove in the crust that didn’t make it to the big time. It runs about five hundred kilometers, and then it ends.”

“You want to detour around?” Ryan said.

Radkowski shook his head. “No, that would probably take at least two days, and we don’t have extra time to spare. And, besides, we might as well get started rappelling. We’re going to be forced to, later, anyway.”

Trevor looked into the canyon, and shuddered. “You’re joking.” He looked at them. “Tell me you’re joking.”

But neither of the other two were laughing.

Ryan went back to the rockhopper to fetch the block and tackle.

The cable was made of a superfiber material called Spectra 10K. It consisted of a thread of buckminsterfullerine nanotubes woven in a matrix of polyethylene. It was nearly as thin as spiderweb, and despite a coating of fluoropolymer, almost as invisible.

Fifty kilometers of the superfiber was wound up on a silicon-carbide deployment spool barely larger than Ryan’s fist. Despite its thinness the cable was plenty strong enough to hold the weight of the entire team, and the rockhopper itself.

Radkowski tested several rock outcroppings at the rim of the canyon, and chose one that was part of the bedrock, or at least something so large that the rockhopper could not move it. The bedrock was a dark, dense basalt, its surface smooth and uncracked. Radkowski drilled an anchor point into the rock, and Ryan fixed a titanium bolt into the hole with an epoxy plug. A second bolt was fixed for redundancy, and then a separate safety line was set with a third and fourth anchor. Radkowski affixed the cables, with Ryan watching over to check his work. When they were done, he called Tana over and made her repeat the checkout as he watched her.

They were ready to go.

Getting Estrela out of the rockhopper was a difficult task. Her sprained ankle, taped firmly, could be forced into the Mars suit’s boot, but her arm was still too swollen to slide into the form-fitting sleeve of the Mars suit, even with the piezoelectric fabric fully relaxed. Tana finally solved this problem by taping Estrela’s left arm firmly to her chest, as if she were cradling her breasts with her arm. They could then shut the chest carapace with her arm inside the shell. Estrela told her that as long as she did not try to inhale too deeply, it felt okay. A balloon patch sealed the opening where the sleeve should have been.

“That should hold,” Ryan said.

“You’d better help me, I think,” Estrela said.

By leaning on Tana at one side, and with Ryan supporting her on the other, they got her out of the rockhopper and moved her over to a shelf of rock where she could watch.

Radkowski entered the rockhopper, slaved the controls to a remote unit, and then sealed it up.

“You all know enough not to try to touch the cable with your hands,” Radkowski said. That had been covered in their training, but apparently he wanted to make sure. “If you have to handle it, use the deployment spool, or else use a handling tool. But it would be better just to stay clear.” He looked at each of them, and waited until they nodded. “Good.”

A take-up reel specifically designed for fullerine superfiber was fixed onto the anchor cable. One control on the reel loosened or tightened a friction brake on the deployment reel. A second control allowed them to spool the fiber up onto the take-up reel at a gear ratio of a thousand. A separate attach-point held their safety line.

Using the remote, Commander Radkowski inched the rover to the edge of the cliff. The nose of the vehicle dipped, and for a moment he hesitated.

Then, trailing behind him a fiber as thin and as invisible as a spider’s thread, he drove the rockhopper off the cliff.

4 Thread

John Radkowski had had experience with superfiber cable nearly ten years before. On the space station, it had been used to dispose of garbage.

In the twenty-first century, Radkowski discovered, the job of astronaut was a half step down from truck driver.

Expensive, high-tech satellites were delivered by unmanned space boosters: cheap, reusable, and too small to ferry humans, they made fortunes for the farsighted investors who had invested in the low-cost transportation and built the whirling network of satellites that surrounded the Earth like a plague of gnats.

To launch people into space, though, they still used the ancient space shuttle. Refurbishing and upgrading had made the shuttles more efficient, adding all-electronic controls and liquid-propellant fly-back boosters, but they were still recognizably the fragile white elephants that had flown in the previous century. Decades of pampering care had made each shuttle orbiter idiosyncratic, with its own set of operating procedures and engineering work-arounds for misbehaving parts. With never quite enough money to adequately refurbish them, and far too little to engineer a new launch system, the space shuttles were still the best way to reliably launch humans into space.

The job of astronaut meant that Radkowski ferried scientists up and down to the space station and was responsible for shepherding the scientists while they were in space, making sure that they followed safety regulations and didn’t do anything that would jeopardize the station or their own lives. This, he discovered, was a tough job. The scientists—pierced and pony-tailed young men with goatees and glasses, earnest-faced young women with irreverent T-shirts and disconcertingly direct gazes that he had trouble meeting—had almost an uncanny instinct for skipping safety rules and getting in trouble.

It was a job.

The first time he had visited the space station he had been impressed with the sheer size of it. The modules had seemed small when he trained in the weightless tanks, but once out there, in orbit, all the modules together with trusses and external experiment modules and solar arrays and appendages, it seemed to be huge.

Inside, the first thing to hit him was how noisy it was. He had expected silence, or perhaps the muted hum of an air circulation fan. Instead it had been full of sounds: clatters and clicking and hums, buzzes of machinery and whirring of fans, computers and lab equipment monitors beeping, voices carrying from modules far away. Then he was impressed with how cluttered it was. Later he amended that: not cluttered, exactly, just crammed. Every wall was filled with things, and in a space station, that meant the “floor” and the “ceiling” walls as well. It was almost impossible to find anything, unless you remembered to make a clear note of where it had been put.

His job was unglamorous, taking care of the routine. His real assignment, he knew, was to be prepared for an emergency, but in the interim there was no end of tasks: vacuuming air filters, calculating garbage dumps, scheduling orbital maintenance burns, and doing preventative upkeep on the ten thousand valves and fans and pumps that kept them alive.

He met Ryan Martin on his fifth ferry trip up to the orbiting laboratory.

Ryan had, at first, seemed to be just another of the scientists: a pony-tailed young man with a growth of facial hair just too short to be called an actual beard. He found Ryan buried in the equipment or taking data or talking with the other scientists; John Radkowski had never been good with people, and it took him a long time to even learn his name. Then it surprised him to find out that he was not one of the scientists at all, but actually one of the Canadian astronauts, on his first mission to the space station. It wasn’t his job to fix the equipment; it wasn’t his job to take data or talk to the scientists. He just liked doing it.

The American space station—it was by name an international space station, but everybody called it American—was not the only space station in orbit.

The Russians had originally been a partner in the American-led space station program, but after the bloody civil war and the war of Kamchatkan independence, they had dropped out. Nobody had ever thought that their space program would ever be resurrected, but, dogged and determined, the Russians had held on. Small, cramped, and perpetually on the verge of breaking down, the Mirusha was built and kept operational—barely—as a matter of national pride. Its name, the “little Mir,” was a tribute to the earlier Mir space station, long since burned up in the Earth’s atmosphere. The Russians did not intend for anybody to forget who had had a space station first. It also meant a little world, appropriate for the tiny cylinder of atmosphere in orbit around the Earth; or with a slight change in pronunciation and spelling, it meant “little Mary,” which was the pet name the Russian cosmonauts unofficially favored.

As it happened, although the Mirusha was at a nearly identical altitude, it had an orbital plane tilted in a different orientation. The laws of orbital mechanics mandated that there is no easy way to change orbital planes. To get to the Mirusha from the international space station required so great an orbital plane change that the easiest way to do it would actually be to return to the Earth and take off again into the new orbit.

So when the news came through the grapevine that the two Russian cosmonauts in the Mirusha were in trouble, that the station was leaking and the Russians had blown up two launch vehicles trying to rescue them, John Radkowski nearly ignored the news. They would be rescued, or not rescued, but the situation, he figured, had nothing to do with the American space station, or with him.

5 Descent

They lowered the rockhopper slowly, with Ryan watching the cables to make sure that they didn’t snag or rub. The cliff was smooth and almost vertical. Even in his Mars suit, Ryan Martin was sweating. Lowering the rover was exacting work, and he was terrified that a frayed cable would let the rover slip, or a miscalculation might let it swing into the rock face.

It took them over an hour to lower the rockhopper two hundred meters to the top of the scree. As soon as they had all six wheels resting on the talus slope, to Ryan’s relief, Commander Radkowski called a break.

Ryan took a deep breath, and then lay flat back on the ground, face upward. It was a relief to stare into the blank flatness of the sky and not worry about a rope snagging and the rover tumbling down the cliff.

After a brief rest, it was time for the crew to begin descending. The rockhopper was still precariously balanced on the talus slope below, with the taut cable holding it from sliding down the slope. “I can tie off the cable to the rockhopper, to free up the winch to start lowering the crew,” Ryan said.

Radkowski shook his head. “Tie it off,” he said, “but we can’t leave the winch behind up here. We’ll rappel down.”

Radkowski got into the harness first and clipped the rappelling brake into it. He checked, double-checked, and triple-checked the harness and the connections, then checked the anchors.

“Those anchors held fine when we lowered down a two-ton rockhopper,” Ryan said. “I think it will hold you.”

“I’m checking it anyway,” Radkowski said. He leaned back, pulled at the superfiber with his full weight. The anchor, unsurprisingly, held up. He clipped a second line to his harness. “On belay,” he said.

Ryan moved to the deployment spool. “On belay,” he replied. He turned and said, “Trevor, watch me on this, you may need to know.”

“I have done rappelling before, you know,” Trevor said, his voice dripping sarcasm. “I don’t think you can teach me anything. It’s easy.”

“Good,” Ryan said. “Have yon used bare superfiber?”

Trevor shrugged, a gesture all but invisible under the suit unless you knew what to look for. “I don’t see how it makes any difference.”

Superfiber ropes were used for rock climbing on Earth, but almost always the superfiber itself was covered in an external woven sheath. The outer coating gave the climbers something to see, and made it less dangerous to handle. “Watch me anyway,” Ryan said. “You can let me know if I do anything wrong.”

“I’m heading down,” Radkowski said. He stood at the edge of the cliff, looked back over his shoulder, and then leaned back over the edge, holding on to the rappel brake with one hand, leaning back farther and farther until he was almost horizontal, and then he matter-of-factly began to walk smoothly backward down the cliff.

6 Dumping Garbage

Each day that he was space station commander, at the end of his shift Radkowski would float through the space station, checking all the seals, verifying that the safety equipment was accessible and that none of the pressure hatches were blocked by cables or equipment. He came across Ryan Martin in the electronics laboratory module. He was working on an electrical breadboard that was connected to a microwave antenna pressed hard against the small external porthole. From the look of it, Ryan had built it himself.

“A C-band transmitter?” Radkowski said. “You have a frequency-control permit for that?”

“Nah,” Ryan said. “Nobody uses those old low-frequency microwave bands but the Russians; a permit would be nothing but paperwork. Anyway, it’s a low-power rig, not good for much but orbit-to-orbit.”

Radkowski liked the young astronaut, but it bothered him when he dismissed management directives so quickly. Who knew what experiments the science crew might be running that could be ruined by unregulated electromagnetic interference? Well, for that matter, Ryan Martin probably did know—he kept up with all the work that the scientists were doing, and seemed to always know what experiment runs were being scheduled when.

Ryan looked at his calculator. “They should be over the horizon any second now.” He powered up his homemade transmitter. “Mirusha, this is Space Station. Mirusha, Space Station. Are you there?”

“Da, Mirusha here.” A heavily accented voice. “This is Martin?”

“Yes, Martin here. How are you holding out down there, buddies?”

“Holding out not so good.”

“Any chance of rescue?”

There was a long pause. “We think not.”

“Can you use your return capsule?”

“No.”

The Mirusha had an ancient Soyuz module attached. The Soyuz spacecraft was, according to the design specifications, the lifeboat that the crew was to use to return to Earth in the event of a failure. But the Soyuz had been designed for only one year in orbit.

“We have been using it for junk storage,” the Russian said. “We have been removing out the junk and try to power up the systems. No is working.” Long pause. “Is designed for one year in orbit. Is now twelfth year. Nothing works. Is junk.”

“Better than suffocating.”

“No,” the Russian replied. The signal was beginning to acquire static. “Cannot undock, my friend. Is welded to Mirusha. Not even big hammer can work to undock.”

“Signal’s breaking up, buddies,” Ryan said. “I’d better sign off. Hang in there, buddies.”

“Da,” the Russian replied. “We will hang here. Where else we hang, no?”

And then there was nothing but static.

“Passed over the horizon,” Ryan said. “If we had a joint data-relay agreement, I could relay communications, but as it is, that’s it for today.”

Radkowski hadn’t realized how bad the Russian’s situation was. But there was nothing they could do about it, he knew. The Russians would have to solve their own problems. “You talk to them every day?” he asked. It was an odd hobby, talking to the other space station over what was, essentially, an amateur radio link, but there were no regulations against it.

“When there’s a line-of-sight window,” Ryan said. “I like Russians. They’re the friendliest people in the world. And their space station may be small and cramped and low-budget, but it’s still a space station, and it’s great that they’ve managed to keep it going, with a budget of old paperclips and broken rubber bands.”

He paused for a moment, and then added, “If nobody else is going to do it, I will.”

“You will what?” Radkowski asked “Why, I’ll save them.”

Radkowski chuckled. “Right,” he said. “You do that.”

Garbage is a big deal on a space station.

Garbage accumulates. Food containers and byproducts, used and reused pieces of paper, human waste, broken equipment, worn-out underwear, used chemicals, filled barf-bags, shaving bags, and vacuum-cleaner bags, sanitary napkins, used-up sponges, biological sample containers, dead petri dish cultures, used personal hygiene supplies, wastewater too contaminated to recycle—garbage accumulates. With every docking of a logistics transfer vehicle, more material is brought up to the space station, and all of it, eventually, becomes garbage.

Some of it can be returned to Earth with the shuttles. But more refuse and wastewater is generated on the space station than can be returned to Earth in the empty space in a personnel transfer module.

Garbage can’t be just thrown overboard; garbage tossed out a hatch would accumulate in the same orbit as the station, turning into lethal debris at the orbital velocity of 17,000 miles per hour. Not even the wastewater can be vented; one of the benefits of the station is to use the high-vacuum environment of space, and a wastewater dump would contaminate the environment near the station, destroying its usefulness.

Instead, garbage is lowered on a string.

The principle is simple. A month’s load of garbage is placed into a plastic disposal bag, which is attached to one end of a spool of thin super-fiber. The garbage load is dropped out the nadir hatch and nudged infinitesimally backward in orbit. A satellite in its own right, but tethered to the spacecraft by the superfiber cable, the garbage-satellite drops into a lower, and hence faster orbit. It moves ahead of the station and unwinds the superfiber behind it. A brake on the superfiber reel pulls back on the garbage, and the more the garbage is pulled backward, the lower the orbit it drops into. At its full extension of twenty kilometers, the garbage satellite hangs directly below the space station. Now the superfiber cable is pulling straight outward on the garbage. And then the cable is cut.

When the cable is cut, the garbage satellite drops into an orbit lower yet. The orbit, in fact, has a perigee which is lower than the space station’s orbit by exactly seven times the length of the tether. Left to itself, the garbage would diverge from the space station by a hundred and forty kilometers. But an orbit a hundred and forty kilometers below the space station skims through the Earth’s atmosphere. Anything in such an orbit will burn up.

And so, in the form of a briefly flaring meteor, the garbage is returned to the Earth it came from. It was a far more efficient way to deorbit garbage than using a rocket; no fuel is needed, and the superfiber tether was a low-technology system no more complicated than a fishing reel.

John Radkowski was in command of the station and had just finished running a garbage dump. It was one of the more interesting duties, actually; if performed incorrectly, the superfiber cable could snag or could go into an oscillation such as the “skip-rope” mode or, in the worst-case scenario, the brakes could fail and the tether deploy too quickly, rubber-band itself back into the station, and hit any of a million possible damage points with a two-ton wrecking ball of garbage.

When he had completed the garbage dump and returned to the lounge area, he found Ryan Martin and several others already there, engaged in an animated discussion.

“Hi, Ryan,” he said.

“Radkowski,” Ryan said. He was wearing a T-shirt that read: HIGH ENERGY PHYSICISTS HAVE A STRANGE CHARM. He floated with the tip of one foot hooked under a loop to keep him from drifting away. He was oriented sideways to Radkowski’s local vertical; it didn’t seem to bother him, although Radkowski still had trouble adapting to it. “What do you think?”

“About what?”

“The rescue, of course.”

Radkowski blinked. “I’m sorry. I don’t know what you’re talking about.”

“The Russians, man,” Ryan said. “The cosmonauts. We’re going to rescue them.”

Radkowski shrugged. “No, of course not,” he said.

Ryan Martin shook his head. His body rotated in counterpoint, and the foot he had hooked under a restraint loop popped loose. He started drifting. “If we don’t rescue them, it’s damn certain that nobody else will,” he said. “They’re leaking. They’ve got five, maybe six days. Who’s going to rescue them that fast? Not the Russians—that last blast tore the hell out of their pad; it will take them six months to get back operational. Not the U.S.—we have only four shuttles; two of them are up here with us, and we can’t get them down and then back up again that fast. The other two are in for refurbishment; they’re going nowhere. Not the Brazilians—they can’t hit that orbit from their launch site. So, if we don’t save them, then who will?”

“Don’t be ignorant,” Radkowski said. “Can’t get there from here. They’re in a completely different orbital plane.”

Ryan smiled. “The crew return vehicle can do it.”

Radkowski shook his head so vigorously that he had to hold on to a loop to keep from moving. “Not enough delta-vee for a plane change. Not by half.”

Ryan Martin nodded. “Nope. So we have to be clever. We have to be very, very clever.”

Ryan Martin, as it turned out, was clever.

The crew return vehicle was a tiny, four-person lifting body. It had been designed to be an ambulance, an emergency way to land an injured astronaut fast. It had a rocket engine for the deorbit, but not enough fuel to make the plane change needed to get into the Russian orbit. Plane change maneuvers need a tremendous amount of fuel; even if every drop of rocket fuel in the space station could be used, it would not be enough to get the little vehicle into the right orbital plane.

Ryan’s plan was to use the tether. The tether was used to drop garbage downward, but there was no reason it couldn’t equally well be used to sling the crew return vehicle outward. He calculated that four hundred kilometers of tether, twenty times the amount used for a garbage dump, would toss the little lifting body into an orbit with an apogee of five thousand kilometers above the Earth. “That’s into the Van Allen radiation belts,” he said, “but I’ll only be there for less than an hour, no big exposure concern there.” At the apogee of the orbit, he would fire the crew return vehicle’s little rocket perpendicular to the direction of the orbit, as well as two solid propellant STAR booster rockets stolen from the perigee kick motors of satellites being repaired on the station. The trick, as he pointed out, would be to gain altitude before trying to do the plane change. The farther away from the Earth, the easier it is to make a plane change, and the added five thousand kilometers that the tether boost could give him would make an enormous difference.

Radkowski closed his eyes, trying to picture the situation. He wasn’t good at doing math in his head. Five thousand kilometers, that was, what, three thousand miles. Slightly less than one Earth radius. “It’s still not enough,” he said.

“Right,” Ryan said. “Not enough. Yet. Okay, here’s what happens next. The return vehicle is screaming in from five thousand kilometers, see. It has a lot of excess kinetic energy to dissipate. So what happens? Here’s what happens. Highly elliptical orbit. I dip into the atmosphere. But, here’s the trick. I don’t just use the atmosphere to brake. The return vehicle has lift, right? It’s a lifting body. So I point it sideways. Roll the beggar over ninety degrees, use the lift as a vector. I can take my excess delta-vee, and I can turn it into plane-change vector. Two passes through the atmosphere, I’ve got the orbit circularized, and as a free bonus, I get my plane change. Piece of cake.”

“Shit,” Radkowski said. “Does that really work?”

Ryan had been spinning lazily end over end as he talked. As he finished talking, his head was in the middle of the lounge, his feet next to the computer console. He reached out with one foot and tapped the keyboard. The screen lit up. Ryan smiled. “Believe it,” he said. “I’ve got it all worked out in computer simulation.”

Radkowski nodded. What Ryan was looking for, he realized, was not for somebody to check his work—it was obvious that he had complete confidence in that. So what was he asking about? “You’re requesting for permission to use the CRV?”

Ryan Martin shook his head. “Radkowski, I’m not asking your permission. I’m going, whether you agree or not.”

“You take that CRV without permission,” Radkowski said, “and they’ll kick your ass so far out of the astronaut corps that you won’t need a booster to get into orbit.”

“Maybe they will.” He shrugged. “Nevertheless, permission or no permission, I’m not going to leave them to die.”

“Okay,” Radkowski said. “We’ll do it.”

Ryan reached out a hand to stop his slow spin and looked up at Radkowski in surprise.

“Just one minor detail,” Radkowski said.

Ryan smiled. “Name it.”

“This mission you’re proposing is dangerous as hell, more than likely it’s not going to work, and even if it does work, it may already be too late to rescue the Russians. Half-baked, untested, dashed-together schemes like this are a formula for killing pilots. There’s no chance I’m going to let you do it.”

“It’s not dangerous,” Ryan said. “I know I’m low on pilot-in-command hours, but the computer will be doing the flying. If it looks like I can’t make the rendezvous, the computer will tell me, and I will abort to Earth.”

“No, you won’t. You’d only end up killing yourself, and I’m not about to allow you do that,” Radkowski said. “I’m going to fly it myself.”

7 Descending

Rappelling down is the part of a climb that most rock climbers like least. To Trevor, however, rappelling was the best part. It gave all of the giddy thrill of hanging on a rope over immense heights, with far less work than actually climbing. He had rappelled long before he had ever climbed, driving with his older brother to the top of canyons in Arizona and rappelling down the cliffs. So he knew about rappelling.

Nevertheless, he watched Ryan as he fed rope out. The superfiber was different. The fiber itself was coated with a monolayer of fluoropolymer that gave it an incredibly low friction; this meant that the fiber was less likely to snag on protrusions or be sawed through by a sharp corner, but also meant that only the specially designed braking mechanisms worked well on it.

The commander was smooth and matter-of-fact about belaying down. Trevor had always descended a cliff in bounces, pushing off and dropping, letting the cable swing him back into the cliff like a pendulum. It was more fun that way. The commander, though, methodically paid out line through the braking fixture, and walked step by step backward, his eyes fixed on the rock at his feet.

Boring.

When the commander got to the rover, he called up “off belay,” and Ryan relaxed.

The next step would be harder. With one arm useless, and an ankle that would not take any strain, there was no way that Estrela would be able to rappel down the cliff.

Ryan strapped Estrela tightly into a harness and attached a belay line for safety.

“Santa Luzia,” Estrela said. “Be careful, will you?”

Ryan set the fiber into the winch. “I’ll do the best I can,” he said.

8 The Rescue

The tether launch from the space station had been flawless, a high-stakes game of crack-the-whip, with John Radkowski, alone in the crew return vehicle, at the very tip of the whip, flying off on a precisely controlled trajectory at the exact apex of the sling. He had kept his hands off the controls during the descent through the atmosphere. No human could maintain the knife-edge tolerances needed for a hypersonic lifting aeropass, and so the guidance computer, with its crystalline logic and perfect mathematical calculations, had done the flying, comparing the predictions of the computer model with the performance of the actual vehicle a thousand times a second, adjusting in real time for variations in exospheric density and discrepancies between the computer model and the actual vehicle.

Now, floating in the crew return vehicle, there was nothing left to do but wait for the slow pirouette of orbits to bring the Mirusha station into range. It seemed as if the vehicle was motionless, and the Earth, endlessly varying, flowing like a sluggish river beneath it. John Radkowski was waiting, alone in space. It was in situations like this, when he had nothing to do but wait, that Radkowski was alone with his inner resources, and found them wanting. He felt lost in an immensity of void stretching off in all directions, and with the realization pounding in from all around him that he was nothing, an insignificant speck in the universe.

The thought both comforted and terrified him.

Focus on the control panel. Check the fuel levels again, for the hundredth time. Check the battery voltages. Check the radios. Focus on the radar. Is that the Russian station? No, it’s still too early.

His breath came in short, shallow pants, and he struggled to control his breathing, to avoid hyperventilating.

Focus on the control panel. Breathe evenly. Is that signal acquisition?

Yes. The indicator light glowed with the acquisition of carrier, and then the radio spoke. “CRV-1, here is Nordwijk. We’ve got you on the screens.”

The voice spoke in a crisp, Scandinavian-accented English. “You’re looking good.”

“Nordwijk, CRV-1,” he said. “Thanks for the update. How long before I expect to acquire signal from Mirusha?” The mission control at Houston had been cool toward the idea of trying to fly a rescue mission—probably they still remembered the humiliation of the Russians pulling out of the space station project—but they had not actually forbidden it. The European space center in Nordwijk, on the other hand, had been enthusiastic, and guaranteed him as much help as they could give. This was little enough—radar readings from the ground tracking stations to confirm what the interior navigation of the crew return vehicle already told him—but he was glad enough for it.

“CRV-1, you should be getting transponder now,” Nordwijk told him.

He frowned. He was getting nothing. No, there it was on his rendezvous radar. But where was the transponder?

He was coming up on it backward; by the strange ballet rules of orbital mechanics, Mirusha was coming up from behind him as he rose to meet it. He could see it now, a brilliant, lumpy star blazing in the sunlight. “Roger, I’ve acquired it visually,” he said. He checked the rendezvous radar. Eight kilometers, closing rate one-fifty meters per second. He corrected his vehicle pitch slightly and made a three-second engine burn with the maneuvering engine, raising his perigee to bring his orbit closer to synch with the Russians, and checked the radar again. Five kilometers, closing rate fifty-two. In his window, the Mirusha was a fat insect with blue metallic wings. He should be able to raise them on the radio. They knew he was coming.

“Mirusha, this is the American ship CRV-1. Do you read? Mirusha, CRV-1.”

No reply.

The station was dark. He brought the crew return vehicle in cautiously. With the crew on the Mirusha not responding to his increasingly insistent signaling, it would be impossible for him to dock to the station as planned. This was a problem. He was wearing a pressure suit, but it was a precaution against a vehicle depressurization only, not a suit rated for an extravehicular activity. There was no help for it, though. He had come this far, it would be pointless for him to stop.

“Mirusha, CRV-1. Do you read? Mirusha, do you read?”

He brought the CRV in as close to the Mirusha as he dared. He had only one safety line, a twenty-foot line, and he clipped one end of it to the CRV and the other to the hook on his suit. Then he did a final suit check, opened the hatch, and jumped.

The docking hatch was barely six feet. He hit the station’s skin, scrambled for a handhold and missed, rebounded away, and as he started spinning away, by flailing wildly he managed to hook the EVA handrail with one hand. He clutched at it and held on, and then, more calmly, pulled himself toward the hatch.

It opened freely.

There was no way for him to stay attached to the CRV when he went into the airlock. He had to unhook. The manual would have instructed him to attach a second safety line to the Mirusha before unhooking from the CRV, but there was no second line available. He unclipped the safety line and clipped it on to the EVA handrail, trusting blindly that it would be strong enough to prevent the CRV from drifting away and leaving him stranded.

He entered the airlock and closed the inner door. A light should have illuminated when the inner door closed, but the chamber was pitch black. He flicked on his suit light and by its feeble illumination, found the hand-wheel that opened the inner door.

The wheel spun freely. There was no pressure on the other side.

In the long, slow fight against a steady leak to space, the two Russians on the space station had lost their fight. There would be no heroic rescue. The dark space station and the lack of internal pressure told him that there was no one left to rescue.

Time had run out.

In all his future years, John Radkowski would remember that lesson. You can be clever, you can come up with daring ideas, and sometimes they even work.

But sometimes, all of your work and all of your courage is not enough. Space is cold and empty and unforgiving, it does not care about human tragedy or last-minute heroics or brilliant piloting skills.

Sometimes your time runs out.

9 On the Slope

The lesson that John Radkowski had learned from the failed Mirusha rescue was that Ryan Martin was bright, impulsive, and that he needed to be carefully watched.

And the second lesson he learned was that sometimes, despite the best you can do, missions fail. And then people died.

He had no time to waste in thinking about ancient failures, Radkowski told himself. The footing at the base of the cliff was treacherous. He was standing on a slope of loose rock that had broken free of the cliffs above and sloped down at a forty-five-degree angle to the true bottom of the canyon. He tested the surface cautiously. The angular rock fragments ranged in size from small pieces the size of dinner plates to enormous ones the size of refrigerators and even small automobiles. They seemed to be loosely cemented in place by a coating of some form of desert varnish. It seemed relatively stable. Good. He worked a piece that was roughly the size and shape of a guitar loose with his foot, kicked it down the slope, and watched it bounce and ricochet another five hundred feet down the hill. It knocked a few smaller rocks free, but didn’t start an avalanche. Good.

The rock fragments were light yellow, much lighter in color than the dark rocks they had been traversing. The cliff walls were light-colored as well, he noticed, all except for a dark stripe maybe a hundred feet wide at the very top.

He drilled a bolt-anchor into the cliff and tied the rockhopper down to free the winch line. There wasn’t much he could do but wait for Ryan Martin to start lowering Estrela. He didn’t like not being in control, but there was nothing he could do at this point.

He checked the rockhopper again, to make sure it wasn’t about to slide down the slope, and decided it was secure enough that he didn’t need to put in another bolt. Right up against the cliff face the loose rock was almost a ledge. John Radkowski sat.

No sense in doing nothing. He was still high enough up to get a good overview of the base of the canyon. He unpacked the binoculars and scanned the terrain.

From here, the base of the catena looked rougher than they had expected from the orbital view. It was a jumble of tilted slabs of rock.

Painstakingly, John Radkowski began to scout out a path.

10 On the Slope

“I’m sweating,” Estrela said.

“For heaven’s sake, turn on your cooling loop, then,” Radkowski told her.

“It’s already up all the way.”

After lowering Estrela, Ryan and Tana disassembled the winch and were lowering it down to Commander Radkowski. This was a slightly tricky operation—they had to lower it by hand—and Radkowski had little time to hold Estrela’s hand if she had forgotten how to program her interior climate settings. He ignored her.

Estrela went into the rockhopper, still complaining that she was too warm. She was awkward in climbing in, with only one arm, but she finally got inside and pulled the hatch closed behind her. Radkowski barely noticed.

Trevor, then Tana, and finally Ryan came one by one down the cliff. Ryan had to give Trevor some instruction in rappelling—the kid had a tendency to bounce down, instead of lowering himself down at a smooth walk to minimize the stress on the anchors. But eventually the entire crew was standing on the slope at the base of the cliff.

They abandoned the superfiber cables used to descend the cliff; they had plenty of cable, and it was easier to leave the used cable behind than to retrieve it. Dangling down the cliff face, it was almost invisible against the light rock; in the places where it was in shadow it could not be seen at all. Over a few weeks, the harsh ultraviolet from the unshielded Martian sun would slowly chew away the covering, and once the fluoropolymer sheath was gone, the cable would disintegrate quickly. And all that would be left behind would be a few titanium bolts, anchored in rocks at the top of the cliff, to show that they had passed this way.

They had made it down. It had been a lot harder than he’d expected it would be, but they were all down, and they were all safe.

Maybe they would be able to take the big one after all.

11 On the Bottom

The talus slope at the bottom of the canyon was steep, but except for a few minor rockslides when the wheels dislodged loose boulders, the rubble held, and John Radkowski managed to drive the rockhopper down the incline the rest of the way to the bottom of the catena without catastrophe.

As he had expected from his surveying the territory from above, the terrain at the base of the canyon was rugged, cluttered with angular, refrigerator-sized boulders.

At the base of the slope he called a halt for the day, and they found a nearly flat spot and pumped up the habitat bubble. The catena stretched out to either side of them, gently curving cliff faces towering over them, stretching as far as they could see. In the evening sunlight the cliffs turned from yellow to an intense orange.

The habitat had an odd smell, the smell of Mars dust: a sharp, metallic scent, like the smell of a distant thunderstorm, or freshly machined aluminum. It was due to peroxides in the soil. Although they made efforts to keep the suits clean, a little dust had been brought into the habitat with each crew member’s return. It wasn’t a bad smell; in fact, it was almost refreshing—an improvement over the locker-room odor that the Don Quijote picked up, with six people living in it for half a year.

There were the usual evening tasks to accomplish. Each suit had to be checked and refurbished for the next day’s action, the filters cleared, the recycling catalysts renewed, the zirconia cells baked out to clear away the sulfur poisoning. The suits had not been designed for as many hours of continuous hard usage as they were getting; twenty hours was an absolute design limit for the suit’s oxygen generation capacity, and Radkowski wanted to make sure that they stayed well below that limit. Just keeping the suits in shape took an hour each night.

It was hard to sleep. Radkowski preferred free-fall, where a sleeping bag could be tethered to a wall in any quiet nook of the station and the sleeping accommodations would be softer than any feather bed on Earth. He couldn’t stop turning over the events of the day and worrying about how they could rescue the entire crew on a ship that was built for only two crew members. And, if the entire crew could not be returned, how he would choose? Eventually he fell into a restless sleep, but long before he was rested, it was day.

In the morning they set out across the bottom of the catena. The terrain was too rough for the dirt-rover to easily traverse, so Commander Radkowski left the bike strapped to the side of the rockhopper. After a bit of thought he gave piloting responsibility for the rockhopper to Ryan, with Estrela riding as passenger, and ceded Tana her perch on the top. It was a good place for her to scout for obstacles anyway, although he would have never allowed it initially, had he known. He and Trevor went ahead on foot along the route that he had memorized from the ledge above. Since the rockhopper had to pick a slow path over the broken terrain, they were as fast on foot as the rockhopper was.

For the most part, they walked in silence, occasionally making a brief comment over the radio to warn of an obstacle that the rockhopper would do well to avoid. From time to time Radkowski stopped and climbed to the top of one of the larger boulders to make a minute inspection of the terrain with the binoculars. From the far side he had noticed a place on the far rim where it appeared that a runoff channel had been cut into the side of the wall, and he thought that by following the cut upward, they might be able to take the rockhopper to the top with little or even no use of the winch. The bottom of the channel looked rocky, possibly even rockier than the land they were traversing, but nothing he saw made him change his opinion.

“Say, Commander, sir.” Trevor touched Radkowski’s arm, and then quickly looked away. Up to that point he had been unusually silent during the walk. Radkowski glanced at the radio indicator LEDs mounted on his suit helmet, and noted that Trevor was talking on the private channel.

“Here,” Radkowski said.

“I’ve been thinking,” Trevor said.

After a minute or so, Radkowski prompted, “Thinking about what, Trevor?”

“Is it really true, what Ryan Martin said? About the return space ship only being able to carry three of us? It’s true, isn’t it? Is it true?”

Radkowski didn’t say anything. He was tired. It wasn’t something he wanted to deal with right now. They were approaching the far wall of the canyon. He pulled out the binoculars and began to inspect the path up the talus slope. From here the route he had chosen didn’t look so much like a river channel any more, but it still looked like it might be a good way up.

“It is true,” Trevor stated.

“Maybe,” Radkowski admitted. But maybe they could do something.

They would have to look over the Brazilian ship, see what could be left behind, calculate fuel capacity and launch trajectories. At this point it was too early to tell.

But Ryan Martin had seemed worried, and Ryan was one hell of a wizard at back-of-the-envelope calculations.

“It is true,” Trevor said, more softly this time. “That’s like, a real problem, do you know it? Like, how are you going to decide? Have you thought about that yet?”

“No,” Radkowski said. He had thought about it over and over, almost obsessively. He had been unable to sleep. “No, I haven’t thought about it.”

“Oh,” Trevor said. “I though maybe you had.” He was silent for a while, then said, “But, when you do make the decisions, I’m with the ones going back to Earth, right? I mean, that’s not in question, is it? I mean, I’m like a passenger here, not one of the crew. I mean, I’m in the crew, but I’m not one of the professional astronauts.”

Radkowski was silent. The footing was a little tricky here; the rock was dusted with dirt and pea-sized loose stone; it would be easy to slip.

“Shit, Commander, you know? It’s like, I mean, you guys are old, no offense, right? And I’ve got my life ahead of me? So if there’s only room for three I should be one of them? You can see that, right? Right?”

Radkowski was silent, studying the talus slope and the cliff above it. When the silence got to be oppressive, he said, “I haven’t made any decisions one way or the other, Trevor.”

“Oh, come on,” Trevor said. His voice was rising in pitch, almost screeching. “You’ve got to. I mean, you know it’s right, don’t you? I’m the passenger here, for the love of God. You couldn’t leave me behind.”

The rockhopper was coming up behind them. Radkowski stepped aside, waved them around a house-sized boulder that marked the beginning of the upward slope, and pointed up the defile. Ryan, in the cockpit, nodded and waved. It really was a marvel the way the six wheels of the rockhopper rolled up and over the uneven terrain and yet kept the body of the rover nearly level.

“You wouldn’t leave me behind,” Trevor said. “I mean, it wouldn’t be right. You wouldn’t do that, would you? Would you?”

“I haven’t made any decisions yet,” Radkowski said, and deliberately turned his back on Trevor to walk up behind the rockhopper. With luck, he wouldn’t have to. With luck, the problem would never come up.

12 On the Top

Ascending the cliff on the far side of the canyon turned out to be actually somewhat simpler than descending. The channel Radkowski had found led almost to the canyon rim, close enough that the remaining two hundred feet to the top were easily climbed, and bolts set into the rock to anchor cables to slowly winch the rockhopper up. Once out of the catena, they were able to unstow the dirt-rover.

Dazed, slightly dizzy from the constant pain of her arm, Estrela thought to herself, I’ve been stupid, I’ve been stupid, I’ve been stupid. Every rock that the rockhopper crawled over hurt her.

She wanted to snarl and bite when they treated her like a child. She held back, forced herself to appear calm, because she knew that she needed their help to survive, and more, she needed to get on the captain’s good side if she was to be chosen to return.

The crew were beginning to get on each other’s nerves. She could see it in the curt language they used with each other, in their short tempers.

Her attempt at seduction in the rockhopper, the night that Ryan had gone haywire, hadn’t worked. Even before the radio had broken in, the mood had gone bad. Radkowski hadn’t actually told her no, but when she had unzipped his jumpsuit and slid her warm hand inside, he had gently pushed her away. Perhaps if she had a little more time…

She was in pretty bad shape for a seduction right now, with a broken arm. The captain wasn’t the one she’d really like to seduce, though, not by a long shot. And it sure wasn’t Trevor. She saw the way the kid looked at her sometimes, and sometimes she even went out of her way to show him a little skin, to give him a bit of a thrill, but that was just to be nice. She didn’t have any real interest in seducing children. He said he was twenty-one, but to her he sure didn’t look twenty-one. She doubted if he was a day over eighteen. Maybe seventeen. He was just a kid.

No, the one she’d really like to catch alone was Ryan Martin. His slender, lithe body; his long eyelashes and hazel eyes and the intensity of his gaze when he was talking…He was the only one of the crew that she would crawl for. There was something about him, some essential core of sadness…

But it was the captain that she had to seduce, she knew. Ryan was candy. The captain was the key to life and death.

The landscape outside the rockhopper’s viewports was hypnotic, almost magical. North of the Coprates Catena the land was flatter than it had been. She couldn’t name the rocks anymore, but they almost seemed to talk to her. The pain in her arm sang a little song to her, made her head dance. The landscape and the pain, the pain and the landscape; it was all mixed up together in her mind.

13 Edge of the Knife

John Radkowski’s throat hurt.

The scenery was less varied now, flat, uninteresting. Or perhaps it was he who had lost interest in the scenery.

There was another smaller canyon for them to cross, he knew, a branch of the Valles Marineris, before they even came to the main gorge of the canyon. He debated stopping for a day, trying to acquire Earth with the high-gain antenna and asking for advice, but he knew that their chances of success were best if they could make the dash north as quickly as possible, without stopping anyplace it wasn’t absolutely necessary. And, anyway, the advice they had gotten from Earth had been, so far, completely useless. The only useful information he’d received was the part he had gotten on the private channel, the one that the crew—and the population of Earth, following with vicarious attention the unfolding disaster in space—had not heard. The advice had been that they had better come up with a rescue plan to save themselves, because there was no chance of any help whatsoever from Earth.

He didn’t need to waste another day for them to tell him that they couldn’t give him any help.

His throat hurt. There was a metallic taste in his mouth, as if he had been sucking on a galvanized nail. It must be the Mars dust, he guessed; the dust, finer than talcum powder, got into everything. He took a deep sip of the electrolyte fluid, but it didn’t really help.

It was going to be a long day.

Toward midday they reached the next precipice. The canyon was wider here, the far wall barely visible, but he knew that they were south of the main canyon and this was just a spur. Instead of winching the rockhopper down, this time they turned east, following the top of the cliff.

From the satellite photos, it had looked to him that if they navigated right, they could thread a path which crossed over the canyons on a spit of land, a narrow ridge that dropped rapidly on either side.

After about five miles, the cliff edge curved around to the northeast. A few more miles, and they came to a point. To the left, to the right, there was nothing visible but canyon. Radkowski stopped the rockhopper.

Ahead of them, a ridge cut across the canyon, dropping away on both sides. It disappeared into the distance, curving gently downward. It must have been a sharp edge once, carved away from either side by the enormous, unknown knife that had carved the great canyon. But now, millions, probably billions of years later, the sharpness of the ridge had been rounded, and there was, if not actually a level place at the center, at least a wider place, wide enough that perhaps the rockhopper would be able to cross the canyon without descending.

They stowed the dirt-rover on its rack on the rockhopper. He directed Tana, Ryan, and Trevor to walk ahead on foot, roped together for safety. With Estrela in the cabin with him, he took the rockhopper along the narrow trail behind them.

It was like driving on a tightrope. He gave the driving his entire attention; focusing on the tiny ribbon of ridgetop ahead of him as if he could keep the rockhopper balanced by sheer willpower. In a way it was simple; on the narrow cusp of the ridge, there were no obstacles, no boulders, no crevasses. As long as he kept to the ridgeline it was easy.

And at first the ridge was wide enough to be almost a road, sloping slightly downward at a gentle angle. It was wide enough for the three crew members ahead of him to walk side by side, Trevor skipping and running ahead to peer down over the cliff edge on one side, then the other.

“How are you doing there, Commander?” It was Ryan’s voice.

He toggled the radio to reply. “Not bad so far.”

“If you get tired and want me to take a turn driving, let me know.”

“Okay. No problem so far.”

But as they went further on, the ridgeline narrowed. Now it was narrow enough that he could no longer keep all six wheels on the ridgeline. He slewed the rover around crabwise, until it was turned completely sideways on the ridge. Each wheel of the rockhopper had independent steering, and he used this feature to turn all six wheels ninety degrees. Now the rock-hopper could roll sideways, and he could keep the two middle wheels on the peak of the ridge. The two fore wheels and the two rear wheels he extended downward to the full length of the cantilever struts, conforming to the shape of the ridge, pressing against the ridge on either side to give him balance. The belly of the rover was dangerously close to scraping the ridge, but there was nothing he could do about it.

The pressurized cabin of the rover hung out over the edge of the cliff. Below him he saw nothing but an endless slope downward, downward to a bottom that was invisible in the distance below.

Ahead of him, the three crew members were walking in a single file now, Tana in the lead, Ryan at the back. The trail, narrow for the rock-hopper, was much wider for those on foot, but they had also slowed their pace. It was dangerous for them as well. He knew that Ryan Martin had the worst position. If Trevor ahead of him were to slip and fall off the ridge, Ryan would have to instantly jump off of the ridge on the opposite side, or risk having Trevor’s fall pull them all over.

He could feel every bump, every tiny slip of the wheels, and with minute precision, corrected the steering to hold him to the exact top of the ridge. He couldn’t tell how long he inched along the crest, eyes glued to the ridgeline under his wheels. Later, when he could spare his attention to look at the time, he was surprised to realize it had been less than half an hour. Below him, the ridge curved to a bottom, and then slowly began to rise. They were halfway across. And then, slowly, the ridgeline began to get wider, inch by inch, and then at last he could get all six wheels on the top.

His throat still hurt. His eyes were dry, and it felt like the inside of his eyelids had been sandpapered with a rough grit.

They had crossed the canyon.

The next one would not be so easy.

14 The canopy of Creation

With part of her attention Tana Jackson watched her feet; ropes or not, to stumble here could be a fatal error. But the part of her attention that watched her feet was on autopilot; it was as if somebody else were taking care of the walking. The ridgeline curved ahead of her, and with the main part of her attention, Tana just looked out across the vast sweep of the canyon that stretched to either side of her.

The canyon walls were striped, horizontal bands of deep orange and light yellow, separated by hair-thin lines of black; in the midday sunlight they sparkled as if bits of diamond were embedded in them. Even the sky was colorful, shading gracefully from an almost lemon shade at the horizon to a deeper adobe color higher up. There was no other description for it, Tana thought; it was simply stunningly beautiful.

It was more beautiful, in its own desolate way, than anything else that she had ever seen. Impulsively, she turned on the mike, and said so.

There was no answer. She looked over her shoulder at the two roped behind her. Ryan Martin, she could see, was silently enjoying the view. But Trevor was white-faced, his jaw clenched, his face covered with sweat. He’s afraid, she thought.

The rockhopper followed along behind them, going sidewise along the ridge, a mechanical spider. It couldn’t be easy to keep it balanced exactly on the top of the ridge, but it was driven so smoothly, it looked as if it belonged nowhere else. A marvel of piloting, she thought. John Radkowski, whatever else he was, was a cool pilot.

She felt a sudden stab of pity for Trevor. He seemed so young, younger than his twenty-one years. Her heart suddenly went out to him. They had lured him away from everything he knew and loved, and now he was going to die with them, die on Mars, his body, desiccating in the dry cold, mummified in the sand. For her, that was okay—she had always known the risks. But for Trevor, it suddenly seemed so unfair. He shouldn’t even be here, away from his music and his friends and his virtual realities, she thought. He’s not astronaut material, and if it hadn’t been for the lottery, that damn silly fund-raising publicity stunt, he would never even have considered becoming one. He’d be safe and having fun with his stomp music and his friends, just at the age when he would be learning to live, learning to love.

No. That was defeatist thinking.

And, despite it all, it was spectacularly beautiful. They were alone under the awesome canopy of God’s extravagant creation, this magnificent canyon, never beheld by human eyes since the day of its creation.

Tana Jackson was at peace with the world.