“Wait and see.”

  It didn't take long. “Will you surrender?” a voice called.

  “To whom?” Peter demanded.

  “Captain Hans Ort, Second Friedland Armored Infantry.”

  “Mercenaries,” Peter hissed. “How did they get here? The CD was supposed to have a quarantine....”

  “Your position is hopeless, and you are not helping your comrades by holding it,” the voice shouted.

  “We're keeping you from entering the town!” Peter answered.

  “For a while. We can go in any time, from the other side. Will you surrender?”

  Peter looked helplessly at Roach. He could hear the silence among the men. They didn'tsay anything, and Peter was proud of them. But, he thought, I don't have any choice. “Yes,” he shouted.

  The Friedlanders wore dark green uniforms, and looked very military compared to Peter's scarecrows. “Mercenaries?” Captain Ort asked.

  Peter opened his mouth to answer defiance. A voice interrupted him. “Of course they're mercenaries.” Ace Barton limped up to them.

  Ort looked at them suspiciously. “Very well. You wish to speak with them, Captain Barton?”

  “Sure. I'll get some of 'em out of your hair,” Barton said. He waited until the Friedlander was gone. “Pete, you almost blew it. If you'd said you were volunteers, Ort would have turned you over to the Dons. This way, he keeps you. And believe me, you'd rather be with him.”

  “What are you doing here?” Peter demanded.

  “Captured up north,” Barton said. “By these guys. There's a recruiter for Falkenberg's outfit back in the rear area. I signed up, and they've got me out hunting good men for Falkenberg. You want to join, you can. We get off this planet next week; and of course you won't fight here.”

  “I told you, I'm not a mercenary—”

  “What are you?” Barton asked. “Nothing you can go back to. Best you can look forward to is being interned. Here, come on to town. You don't have to make up your mind just yet.” They walked through the olive groves toward the Zaragoza town wall. “You opted for CD service,” Barton said.

  “Yes. Not to be one of Falkenberg's—”

  “You think everything's going to be peaceful out here when the CoDominium fleet pulls out?”

  “No. But I like to choose my wars.”

  “You want a cause. So did I, once. Now I'll settle for what I've got. Two things to remember, Pete. In an outfit like Falkenberg's, you don't choose your enemies, but you'll never have to break your word. And just what will you do for a living now?”

  He had no answer to that. They walked on in silence.

  “Somebody's got to keep order out here,” Barton said. “Think about it.”

  They had reached the town. The Friedland mercenaries hadn't entered it; now a column of monarchist soldiers approached. Their boots were dusty and their uniforms torn, so that they looked little different from the remnants of Peter's command.

  As the monarchists reached the town gates, the village people ran out of their houses. They lined both sides of the streets, and as the Carlists entered the public square, there was a loud cheer.

  Editor's Introduction to:

  THOR: ORBITAL WEAPON SYSTEM

  Weapons Committee, Citizen’s Advisory Council on National Space Policy

  The second Council meeting was in the Fall of 1981, and was also held in the home of Larry and Marilyn Niven. Even more experts attended, so that their house nearly burst at the seams. One session featured Dr. Hans Mark, Deputy Administrator of NASA and former Secretary of the Air Force. Dr. Mark attended as an observer only, but the Council was able to present its views directly to him.

  The first Council meeting concentrated largely on space industries. The second examined the military potential of space. This paper, outlining a futuristic new weapon system, was one result. A few months after the meeting, the Falkland Islands crisis erupted.

  THOR: ORBITAL WEAPON SYSTEM

  Weapons Committee, Citizen’s Advisory Council on National Space Policy

  One of the most difficult security missions which the United States must accomplish is the protection of our interests around the globe. Incidents like the North Korean seizure of the USS Pueblo have demonstrated our weakness in not being able to respond quickly and authoritatively in remote locations. Our only solution to this problem so far has been the naval carrier task force. Carrier-based aircraft can project military force to protect our citizens and allies in remote regions of the world. Unfortunately, the high cost and vulnerability of nuclear carriers and their required aircraft and support fleets make them an unattractive solution.

  We now have the technology to produce a space-based weapon system which can perform the same mission for less cost. The space system is also much less vulnerable and can respond faster to any location on the globe than a dozen carrier task forces spread throughout the oceans of the world. The proposed name for this weapon is THOR, for it would literally give the United States the power to call down lightning bolts from the heavens upon its enemies.

  Brief Description of THOR

  The basis of the THOR weapon system is the fundamental nature of any object orbiting the Earth. To balance the force of gravity, a satellite two hundred miles above the surface must travel at a speed of seventeen thousand five hundred miles per hour. At this speed, the satellite travels around the Earth once every ninety minutes. With a hundred satellites in orbits near this altitude and traveling in random orbital inclinations, one of the satellites will pass over any given location on Earth every thirty minutes. With a thousand satellites, the timing between satellites overhead is less than ten minutes. The basic physics of orbital motion gives us our global coverage; it also gives us the weapon. The extremely high velocity of a satellite in orbit gives it a tremendous amount of kinetic energy. If a one pound object moving at orbital velocity ran into a stationary target, the energy released in the impact will be the equivalent of exploding almost ten pounds of TNT.

  The THOR system is composed of a thousand or more cheap satellites, each made up of a bundle of projectiles, guidance and communications electronics, and a simple rocket engine. When a crisis arises, a THOR command center (on Earth or in space) sends a signal to the appropriate THOR satellite. The satellite then orients itself. At the proper time, the rocket engine fires to deorbit the satellite. When the rocket engine burns out, the individual THOR projectiles are dispersed from the satellite in a prearranged pattern. Instead of blunt noses, the projectiles have sharp points which slice down-through the atmosphere, losing little velocity. Just seconds before impact, a (relatively dumb) terminal guidance sensor looks for a metallic or other preprogrammed target and steers toward it. The result is spectacular: a bundle of tens or hundreds of twenty pound projectiles streak down at four miles per second to strike targets with the explosive equivalent of two hundred pound bombs each. In five seconds the action is over, and the enemy doesn’t know what hit them. All that remains is dozens of luminous trails, each angling downward to a slowly dissipating explosion cloud.

  The major advantage of the THOR space weapon is its capability for quick response while remaining highly survivable. Even if an enemy were to detonate one or more nuclear devices in space in an attempt to destroy THOR, there are a thousand or more widely scattered satellites he must destroy. Because the satellites are at different altitudes and have different orbital inclinations, any holes produced in the global coverage by a nuclear explosion are filled in after several hours by the orbital motions of the satellites.

  An individual THOR satellite is not easy to detect or to destroy. The satellite can be cocooned in foam, which would be difficult to detect with radar anyway and could be shaped to make detection even more difficult (stealth satellites!). The foam would insulate the satellite against the heat and shock of nuclear explosions or laser beams. All the satellite has to do is float around in its orbit and wait for the command to strike a target.

  Each individual projectile is a slender, dense metal rod. No explosive or firing mechanism is necessary. The jet of metal particles produced when a shaped charge warhead detonates is traveling at about the same velocity as a THOR projectile when striking a target. The six-inch diameter warhead from a TOW anti-tank missile will punch through the armor of a heavy tank. The jet of metal from the TOW warhead weighs only a fraction of an ounce; a THOR projectile weighs over twenty pounds! Such a projectile can easily punch through the deck of a battleship and blow a hole through the bottom, blast a crater in a runway, or destroy a bunker. A rain of a hundred THOR projectiles over an area less than a mile across would stop an armored column, halt an amphibious landing, or destroy a supply depot.

  The capability of the THOR projectile is not limited to armored targets. Forming the projectile from dense uranium metal produces an incendiary blast when the white hot metal vapor produced on impact ignites in the air. Such a uranium missile could penetrate the reinforced concrete cover of a missile silo and explode inside as the cloud of uranium vapor detonates. If the projectile were composed of an outer shell with sand-sized particles inside, it could be designed to explode and disperse the particles just before impact. The metal particles would instantly vaporize, with the resulting shock wave flattening troops, aircraft, or other targets much like the fuel-air explosive bombs presently in service.

  Advantages of the THOR Space Weapon

  The advantages of the THOR weapon system are its low cost, global coverage, quick reaction time, and survivability. Unlike an aircraft carrier task force, THOR does not need thousands of highly trained pilots, sailors, and technicians who must spend long months away from home. THOR does not require expensive foreign aid payments to secure overseas bases. THOR does not have a single capital ship as a vulnerable target. THOR is composed of many cheap, hardened satellite packages which act only on command. The system capabilities can be built up slowly but can act quickly in a crisis. All of the system’s capability is useful; none of the projectiles need to be stockpiled or stored and then shipped to the battlefront.

  No major (and vulnerable) ground facilities are necessary, unlike ballistic missiles with silos or other fixed launchers. Every time the Space Shuttle goes up with the payload bay partially full, we could toss in a THOR satellite or two and build up the system gradually and cheaply. The command stations and links for THOR could use multiple channels, existing relay satellites, and several orbital or ground control stations.

  THOR gives global coverage at a time when we are uncertain from one minute to the next where a crisis may erupt. THOR is non-nuclear and surgically precise. The velocity of the projectiles is so high that interception would be impossible before they strike their targets. Before our enemies can react, THOR has struck them down.

  Further Study of THOR

  Several aspects of the THOR space weapon system must be studied before any commitment to development of the system can be made. Some are strategic, some are political, and some are technical.

  We should begin to consider the effects which the existence of the THOR system would produce on our own and our opponents’ defense planning. A firm commitment to the THOR system would involve billions of dollars of defense funds. It will be opposed by those with vested interests in the current weapons systems which THOR might replace and those who oppose any change, whatever the justification. As benefits, THOR may permit the United States to reduce conventional forces in Europe and decrease the number of large carriers built.

  We must consider the impact of THOR on world politics. We would not want to register the orbital parameters of each THOR satellite with the U.N. as is presently required by treaty. The Soviets might consider THOR a strategic weapon aimed at the destruction of their land and sea based ICBM’s. Many countries might object to our umbrella of military power covering the entire planet (others might welcome it).

  If THOR is to be survivable against present and future threats, the THOR satellites must be difficult to detect and to destroy. The shape and composition of the external covering of the satellites must be chosen for low electromagnetic detectability, resistance to orbital temperature extremes, and strength to withstand laser and nuclear attacks. A plastic foam mixed with a refractory material such as aluminum oxide might have the necessary properties.

  The angle at which the THOR projectiles strike determines the size of the de-orbit propulsion system for each THOR satellite. The maximum penetration of hardened targets such as missile silos and underground bunkers would be achieved with projectiles striking almost vertically. Ships and lightly armored targets could be destroyed with projectiles entering at more shallow angles. The steeper the angle of attack, the less time the projectiles spend in passing through the atmosphere and the greater the speed and accuracy of the projectiles will be. To de-orbit the projectiles and bring them down at an angle of thirty degrees from vertical requires almost as much energy as was required to orbit the projectiles initially, and requires a large quantity of propellant for each THOR satellite.

  The de-orbit propulsion system must be capable of long-term storage in orbit without deterioration, yet it must provide a precise change in velocity to strike the target area. The individual THOR satellites are most vulnerable while the de-orbit propulsion burn is taking place, when a rocket exhaust plume is a bright beacon marking the location of the satellite for possible destruction by enemy laser weapon satellites. Two solutions are a cold gas propulsion system (high weight of propellant required) or a very fast propulsion impulse which ends before the laser weapon could be brought to bear on the THOR satellite. Once the propulsion burn has occurred, the individual projectiles are dispersed and are then relatively invulnerable to attack or interception before impact (after all, they are rods of solid metal with a simple terminal guidance system).

  The individual guidance system of each THOR satellite must know its own position very accurately to orient itself to strike the target from orbit. If the command message carries only the target coordinate information, the THOR satellite must be able to compute from this data the proper trajectory to follow to hit the commanded target. Fortunately, computers capable of doing this are small and cheap enough to put in every THOR satellite. With the Global Positioning System navigation satellite network in operation, each satellite could passively receive its own location in space to a very high accuracy while doing nothing to reveal its own position.

  The navigation and command communication system must resist jamming, have secure codes to prohibit enemy takeover of the satellite, be hardened against extremely intense visible or radio-frequency pulses or beams, and permit almost instant reception of the targeting commands. This may be accomplished by multiple ground control stations, multiple space control stations, relay satellites operating on optical or radio frequencies which cannot penetrate the Earth’s atmosphere, and redundant channels of communication spread across the electromagnetic spectrum. Communication by laser beams, which are extremely narrow and almost impossible to intercept, may be possible if the position of each of the thousand or more THOR satellites can be calculated accurately enough to hit the desired satellite.

  The command and control stations must receive the signal from the military commanders containing the target location, calculate which THOR satellite is in the best location to strike the target, and transmit the command to the THOR satellite. The most difficult part of the task will probably be to devise a system to monitor the location of all the satellites in the THOR system without compromising their locations to the enemy. Each satellite may transmit its current position after random intervals to notify the control centers of its updated orbital characteristics (in coded form).

  The projectiles themselves must survive passage through the atmosphere without being damaged or slowed significantly and then home in on an individual target in the target zone. The projectile could be protected by an ablative nose tip which would vaporize and carry off the heat from atmospheric friction during the few seconds of atmospheric passage. At a mile or two above the surface, the nose cap would pop off to expose the sensor(s). Small bumps or tabs at the rear of the projectile would steer the projectile to the target. The projectile itself would be as small in diameter as possible for stability and minimum friction and slowing during high velocity travel through the atmosphere, and to produce a very high cross-sectional density for increased depth of penetration on impact. A twenty pound projectile made of tungsten or uranium would be less than an inch in diameter and three or four feet long. The sensors would only have to detect metal or color contrasts or some other relatively simple targeting strategy. Only ten per cent might hit their targets with such a simple guidance logic, but a bundle of a hundred or more would give enough hits to be effective.

  The high -speed of the projectile through the atmosphere near the ground where the density of the air is highest would produce a luminous bow shock wave directly in front of the missile. Penetrating such a layer might be a problem, but high frequency radio waves, infrared light, visible light, or ultraviolet light might be effective for targeting. A visible light sensor might have a window covered with a filter which passes light of a wavelength which is not emitted by the ionized air in the shockwave. Many new solid-state sensors are now available which detect almost all portions of the spectrum and which can be encapsulated in a shock resistant module.

  The individual THOR projectiles may home in on targets according to preselected characteristics, or targets may be designated using lasers to pinpoint enemy ships surrounding a friendly ship as an example. Characteristics used to select targets in present military weapons include contrast and shape of the target against its background in visible light, long-wave infrared (heat) radiation, and ultraviolet light; reflection of millimeter radio waves from the sky by metal surfaces; and designation of targets with visible or infrared lasers. Coding of laser designator beams would be required to avoid enemy countermeasures. Target designation could be carried by nearby friendly forces, by aircraft, or from orbit by manned or unmanned platforms. Each THOR satellite might carry a mix of sensor tips on its projectiles to insure effectiveness in striking targets, or each satellite might have two de-orbit modules, one with passive sensors for broad targets such as invasion forces, and another with laser designator sensors for precise targeting near friendly forces.