Sparta’s boots touched down gently on the dusty surface of Phobos; she could feel the crunch of the meteorite-blasted dirt through her toes. Head up, she checked her position. The only light was the ocher radiance of Mars, looming above the nearby horizon, filling a third of the sky; the sun was below the horizon. But marslight was quite sufficient for her purposes, and she could see very well. She stood in the center of an irregular plain about two kilometers across, surrounded by groups of low hills over which she could leap rather easily if she wished. The hills were, in fact, crater rims. The highest of them, silhouetted against Mars, was the rim of Stickney, where the structures of Phobos Base stood more perfectly preserved than the graves of lost explorers in the Arctic ice.
She moved off toward the base and found her first step taking her high into vacuum. She remembered hearing a story long ago about a man who had accidentally jumped off Phobos. That wasn’t really possible–though it would have been on Deimos–as the escape velocity here was still faster than a person in a spacesuit could run. But unless she was careful she might easily find herself at such a height that it would take hours to fall back to the surface unaided, a risk she could not afford to take. She had a limited amount of maneuvering gas, and she intended to conserve it. Until reinforcements arrived she had to consider the possibility that
Doradus
had defied her warning. She had no intention of exposing herself in space.
With three long bounds Sparta quickly gained the heights of Stickney’s rim. She stabilized herself on the edge of the deep crater and turned to look up at the
Mars Cricket
hanging upside down in space, its stubby white wings gleaming in marslight against the powdered-sugar stars.
As she looked, a streak of light bisected the black sky and touched the shuttle. Instantly a ball of radiance burst so brightly that Sparta barely had time to hurl herself backward over Stickney’s rim. The autopolarizers in her faceplate saved her eyes, but debris from the blast riddled the landscape. Chunks of metal bounced off the rim where she had been standing; at well over escape velocity they rushed on into space.
When the fire control officer confirmed that the
Mars Cricket
had been destroyed, the commander maintained a demeanor of judicious calm. With luck, the meddlesome Space Board officer had still been aboard.
Communications had no indication that Mars Station traffic control had detected the firing of the torpedo. The satellites surrounding Mars had not been designed for weapons detection or electronic warfare. But the commander could not count on that either.
Phony signals from an ECM drone were intended to persuade traffic control that the shuttle still existed; the decoy had followed the lethal torpedo toward the doomed shuttle and had begun broadcasting imitation
Mars Cricket
transponder code and a characteristic radar signature as it looped slowly away from Phobos. How long could it be before someone decided to question the odd trajectory of the commandeered shuttle? What had the Space Board officer who’d commandeered it already said to the people on the ground? These were exceedingly worrisome questions.
Behind his patrician mask, the commander of the
Doradus
was a frightened man. From the moment he’d first heard the order restricting landing on Phobos, he’d had to resist a powerful temptation to obey it. The warning made no mention of the Martian plaque; why should he risk discovery of his ship? It would have been simple enough to stick to the cover story of engine failure, return to Mars Station for “repairs,” and wait for another day to retrieve the plaque.
For
Doradus
was not what she seemed. She had the lines of a typical atomic freighter, with forward crew module and cargo holds separated from the aft fuel tanks and engines by a long central boom, but these clumsy lines disguised her true power. Her big fuel tanks were segmented, carrying fuel for two separate propulsion systems: her atomic engines were supplemented by a fusion torch comparable to those which powered the Space Board’s sleek cutters. Hidden in her cargo holds there were not only ECM drones and EW decoys, but ultravelocity torpedoes and slow SADs, search-and-destroy missiles.
It was not for this simple mission to Phobos that the clumsy-looking
Doradus
had been secretly armed with enough weapons and electronics to destroy a Space Board cutter or an entire space station, and the commander could plausibly argue to those who had equipped him and sent him here that the risk of jeopardizing that later, greater mission was too great.
Far worse than to reveal the secrets of
Doradus
, far worse than to fall into the hands of the Space Board, would be to fall into the hands of his colleagues . . . if he failed to use every means at his disposal to recover the Martian plaque. No artifact in the solar system was more precious to the
prophetae
or more nearly an object of their worship.
Doradus
would be an invincible devourer of armed cutters and space stations when the millenarian day arrived, but how well would the formidable ship do against one woman on a rock? Of all the machines of transport ever invented, a space freighter was surely the least maneuverable.
Doradus
could descend right down to the crater rims, search the surface of Phobos with optical and infrared sensors and radar, and eradicate anything that moved. But this Troy person could make half a dozen circuits of the little world while the crew was persuading
Doradus
to make one.
A spaceship accelerates along its major axis, and any significant deviation from a straight course demands turning the ship, using the attitude-control jets or, in an emergency, the backup gyros, so that the main engines can blast in a different direction. A typical freighter like the one
Doradus
pretended to be has a mass of several thousand tonnes, which does not make for rapid footwork. Moreover, so far as maneuverability is concerned, it isn’t the mass but the moment of inertia that matters most, and since a freighter is a long, thin object, shaped like a dumbbell, its moment of inertia is colossal.
In any event a freighter’s main engine is far too powerful for fine maneuvers; for minor orbital translations–such as spiraling around an asteroid or small moon–the small rockets of the maneuvering system are used. But to translate
Doradus
through even a few degrees of arc on maneuvering rockets alone took several minutes.
In the ordinary way these disadvantages are not grave–certainly not for a freighter which expects to have cooperation from the object with which it seeks to rendezvous. Nor for a disguised warship which intends to sneak up on its foes or, failing that, to destroy them from thousands of kilometers away, as
Doradus
had just destroyed the
Mars Cricket
.
But for the target to move in circles of ten kilometers radius was definitely against the rules, and the commander of the
Doradus
felt aggrieved. Troy was down there, he felt it in his bones. And she was not playing fair.
Inside the ops room of the makeshift landing strip, Blake shook hands with Khalid. “Soon as you get back we’ll hold a reunion,” Blake said, then lowered his voice. “I can’t give you the details, but I can tell you this: Ellen has solved the case.”
Khalid smiled, and his liquid brown eyes closed in recollection of better times. “I trust your word.” He glanced up through the window at an impatient ground crewman who was beckoning from beside the spaceplane’s open lock. “Your hosts are eager to leave for Labyrinth City. Perhaps you should not give them an excuse to leave you behind.”
Blake squeezed Khalid’s hand for the last time and turned away. He sealed up his pressure suit as he stepped into the lock; in less than a minute he was striding across the blowing sand toward the waiting spaceplane.
The crewman gave him a boost into the lock and followed him inside, helping him into his seat in the plane’s small cabin. Blake glanced forward to the flight deck, but its door was closed. The ground crewman saw to it that Blake was strapped securely into his acceleration couch and then quickly retreated, snugging the double hatches of the airlock behind him.
The plane angled steeply back. Blake found himself peering straight up–the angle of attack was
too
steep, and the acceleration was crushing. Then, just as abruptly, the engines’ thunder ceased. The plane leaped as the boosters fell away. A huge weight lifted from Blake’s chest–
Before he could free himself from his acceleration harness the door of the flight deck opened. Blake peered straight at the pilot he had not met before, and the first thing he noticed was the barrel of the .38 caliber Colt Aetherweight semiautomatic pistol that was aimed at his nose.
What he noticed next was the smiling face of the man holding it, a small fellow with curly orange hair who was wearing a roomy flying jacket that appeared to be tailored from camel’s hair–worth more than a grade six plumber made in a year.
The suitcomm of her emergency spacesuit, though short ranged, was sensitive to an unusually wide band of the radio spectrum–but she could hear only one thing of interest on it–what sounded like the ghost of the
Mars Cricket
, still aloft and drifting slowly away from Phobos, its transponder signaling normally. So
Doradus
had sent a decoy to take the shuttle’s place. Even that signal faded rapidly. Her radio’s range was indeed severely limited.
She would have given much for the microwave sensitivity that had been ripped from her when the pulse bomb exploded in Khalid’s marsplane; she might then have been able to pick up a hint of the position of the
Doradus
, and had she chosen to beam signals of her own, she might have tried playing a few games with its electronic systems. She might even, with her own internal structures, have been able to detect the coded short-range transmission from the buried penetrator.
While flying the
Mars Cricket
into orbit she had mentally run estimates of the penetrator’s likely flight path. The thrust of the little solid-fuel rocket was more than sufficient for it to achieve the 2.1 kilometers per second orbital velocity of Phobos. The robber would have wanted to get the plaque off Mars as quickly as possible; that meant a high-energy parabolic orbit. Fired from somewhere near Labyrinth City as Phobos was high in the sky, the rocket’s flight would have appeared almost vertical. The impact presumably would have been somewhere on the eastern half of the overtaking moon, its leading half.
Sparta was just inside the western rim of Stickney. A few long cautious bounds took her down into the crater’s eight-kilometer-wide bowl and, some minutes later, up its far side. As she flew she moved toward the sub-Mars point of Phobos, the place on the tidally locked moon that always faced the planet. It marked the little moon’s prime meridian; somewhere within the more than 500 hundred square kilometers of misshapen hemispheroid beyond it, the penetrator was surely buried.