The tiny moons of Mars, then, could become oases for space travelers where they can refresh life-support supplies and refuel rocket engines.

If they contain hydrates.

Which is why the Japanese geochemist and the Russian cosmonaut had left the Mars 2 spacecraft to begin the hands-on study of Deimos.

Tolbukhin said into his helmet microphone, "Five minutes to impact. I am arming the penetrator." This was a rocket-powered grappling hook, designed to imbed itself into Deimos’s pitted surface and anchor the two men safely. Without it to tether them, the explorers could go flying off the tiny moon with every step they took, Deimos’s gravity was so negligibly low.

Still Konoye said nothing. He was no longer looking at the looming dark shape of Deimos. He stared instead at the enormous bulk of the red planet hanging overhead. He could not take his eyes off it.

The two men had left the Mars 2 spacecraft an hour earlier, decked in hard-shell pressure suits and tubular metal frames of mobility units wrapped around their bodies. They looked like brightly colored fat robots stuck inside individual jungle gyms. The mobility units contained personal equipment, life-support systems, and the thrust motors and propellants that allowed them to fly from the orbiting spacecraft to the Martian moon named after the Greek word for dread.

Slowly revolving a few kilometers away, the tethered Mars 1 and Mars 2 spacecraft looked like miniature models, white and silent, lifeless and desperately far off.

To Konoye, Deimos was an ugly, irregular, dark-gray lump of crater-pitted stone blotting out the stars, covering half the sky. Enormous. Menacing. And Mars itself seemed terrifyingly huge, crushingly massive. In his perspective, the ponderous enormity of the red planet loomed above him, glowering overhead, pressing down, squeezing the breath from his lungs. The three immense volcanoes of the Tharsis Bulge and the even bigger caldera of Olympus Mons seemed to be staring down at him like the four monstrous wide round eyes of a demon, staring balefully.

The Japanese geophysicist had trained for this moment for more than three years. He had gone through all the simulations on Earth and experienced long weeks of zero gravity aboard the space stations in Earth orbit. He had prepared himself thoroughly to lead the firsthand study of Mars’s two moons. Waiting for their turns behind him were a Russian geologist and an American geophysicist. But in this moment Japan was first.

Yet Konoye had not reckoned on that enormous expanse of red looming above him like a powerful, palpable force. This was no simulation. Mars hung over him and he could feel it squeezing down on him while its many-eyed demon glared at him, angry and demanding. Something in his childhood awakened and began screaming. Some long-forgotten nightmare tore at his mind. He had to get away. Get away!

Blindly Konoye fired the thrusters of his excursion unit. In panic he fled from the overpowering presence of Mars.

"Wait!" shouted Tolbukhin. "What are you doing?"

Konoye was jetting away from Mars, away from Deimos, away from the spacecraft in which he had lived for more than nine months. His gloved hands clamped rigidly on the thruster controls, like a catatonic or a man already in rigor mortis.

"Stop!" Tolbukhin yelled, so agitated he lapsed into Russian. "You fool, you’ll kill yourself!"

But Konoye was fleeing, panic-stricken, unable to speak. The cosmonaut punched his own thrusters into life and jetted after him, even as his helmet earphones erupted in wild commands from the team in the Mars 2 spacecraft monitoring their excursion.

Under the remorseless hand of blind nature Konoye had turned himself into a miniature asteroid. At full thrust the propellants in his tanks quickly ran out. In the frictionless vacuum of space he continued to fly away in the same direction, straight out into the endless void between worlds.

Tolbukhin could not catch him. Within a few seconds his training asserted itself — abetted by the frenzied shouts of the monitoring team in his helmet earphones. He reversed course and headed bark for the safety of the Mars 2 craft.

It took no more than two hours for the rescue team to reach Konoye in one of the emergency transfer vehicles they all referred to as "tugboats." The Japanese scientist still had several hours of air in his suit tanks. His heater and other life-support equipment were still functioning.

But he was quite dead. The autopsy promptly conducted by Dr. Yang aboard the Mars 2 craft found the cause of death to be a cerebral hemorrhage. Tolbukhin shook his head when he heard the verdict.

"He died of fright," muttered the Russian. "He died of deimos, dread."

"He died of natural causes, then," Jamie said.

Vosnesensky shrugged. "But would he have died if he had remained on Earth? Or if he had not gone on the EVA?"

Jamie shrugged back at the Russian. "We’ll never know."

They were in the cramped confines of the airlock, slowly, laboriously pulling themselves out of their hard suits, tired from the day’s work, depressed by the news from orbit.

"I still don’t see why Li had to order us to return to base," Jamie grumbled, "Doesn’t he understand what we’ve found here?"

"What have we found?" Vosnesensky smiled tolerantly. "An optical illusion?"

"Well… maybe," Jamie admitted.

"When we get back to the base we can ask the team in orbit for computer enhancement of the videotapes. If there is any chance that the rock formations are man-made… er, Martian-made — we will certainly return here."

"It’s more than that, Mikhail. This canyon is an open book of the history of the planet. We should be here, studying what the rocks have to tell us. Joanna and the life-sciences people should be down there where the mists hang around all day. That’s the best chance for life to be found."

Vosnesensky had peeled down to his water-tubed skivvies. Jamie was still in his hard-shell pants, leaning against the airlock bulkhead to tug off a boot.

The Russian looked at the red dust on Jamie’s boots and sniffed loudly. "It smells different from the moon."

"What?"

"After a moon walk your shelter smells as if someone had shot off a revolver inside. The lunar dust that clings to your suit and boots has a burnt odor to it. This stuff — " he fingered the thin film of rusty powder on the sleeve of his empty hard suit " — this Martian dust smells different."

Jamie wrinkled his nose. "Now that you mention it — it smelled the same way back at the dome, didn’t it?"

Nodding, Vosnesensky pulled on his hard suit’s arm; it swung upward with the slight hissing sound of its slick Teflon shoulder joints.

"Smell."

Jamie sniffed at the metallic arm. Pungent. Harsh. Then he pulled one of his own gloves from the rack where he had tucked them. Somewhere deep in his memory the picture of an approaching thunderstorm formed itself, strange eerie afternoon light, the summer air heavy and still. Lightning flickering against approaching black clouds.

"Yeah. Strange smell. Almost like… could it be ozone?"

Vosnesensky rubbed at his eyes. "Yes, I think you are right. Ozone."

"The soil’s loaded with superoxides," Jamie said.

"And in the high temperature inside here they are breaking down, baking out of the dust."

Jamie’s own eyes were smarting now. The rover’s airlock was much smaller than the clean-up area in the dome. "Maybe we ought to get out of the airlock."

"Not until we clean the suits."

Jamie finished pulling off his boots and wriggled out of the hard suit’s pants. They vacuumed their suits thoroughly, yet the pungent odor remained in the airlock. Then he followed Vosnesensky through the hatch that led into the main compartment of the rover’s forward section.