George Lucas, according to popular movie lore, modeled many of his on-screen battles in the Star Wars series on World War Two film footage. X-Wing Fighters swoop through space in tight formation and dive-bomb, gigantic capital ships sluggishly exchange broadsides, and the enemy is engaged only at naked-eye distances.

Wonderfully fun images for a classic popcorn fantasy. But how accurately do they reflect the probable shape of future space warfare?

Judging by such factors as how modern weapon systems are evolving, the harsh realities of space as an environment, and the foreseeable capabilities of space travel, the _Star Wars_ model looks to be, well...

Dead wrong.

In this two-part article we’ll take a more realistic, hard-science approach to what it will take to fight and win a battle in deep space. Part One deals with the environment of space and combat strategies needed to succeed in it. Part Two will address offensive and defensive weapon systems.

A NOTE ON TECHNICAL ASSUMPTIONS

This article assumes a level of technology for our hypothetical combatants consistent with that needed for commonplace deep-space travel. This is pretty much the tech level of a "typical" space opera civilization minus the technologies that don't have a solid theoretical basis in real science. So the tactical impact of fanciful technologies such as faster than light travel, force screens, reactionless drives, and so on won't be discussed here. However, more hard-science speculative devices, such as fusion rockets, x-ray lasers, near-sentient artificial intelligence, and such will be assumed to be routine for such cultures.

SPACE: THE ULTIMATE WILDERNESS

Space is vast. Yet just how vast is hard for us humans to visualize intuitively. We can crunch the numbers, bandy about terms like astronomical units and light years, but our limited analog brains have a hard time really wrapping themselves around the scale of space. We’re just not evolved for that kind of mental imaging.

Here’s a little exercise that might help: Take a tiny bit of paper, and tear and roll it until its about the size of the period at the end of this sentence. This represents our Solar System. Stand in the middle of a hallway or a gymnasium and hold it up. Now have a friend take a similar piece of paper and hold it up about 11 meters (about 35 feet) away. This represents Proxima Centauri, the nearest star to our own, 4.2 light years away.

Now imagine the hallway or gym is completely empty except for the tiny bits of paper. No furniture, no fixtures, no one holding them up, just the bits of paper floating and nothing else. That’s what space is: an enormous volume of _nothing_, dozens of cubic light years of near-absolute emptiness surrounding us in every direction.

Even within the Solar System, the scale of things is still hard to visualize. Putting Earth and Mars on the same period-sized scale as above, the planets would never be closer than about four meters at closest approach. And between the tiny speck that contains everyone we know and love and the other tiny speck we occasionally send robots to, there is nothing but billions of cubic miles of empty void.

All this space provides the perfect hiding spot for even the most gigantic of ships found in our favorite galaxy-spanning space operas. Even a vessel kilometers across would simply be swallowed up in the sheer immensity of the nothingness out there, a microbe in an ocean.

Which brings us to the first, and most vital, consideration for deep-space combat: finding the enemy.

DUSTMOTES IN THE INFINITE

You have to know where to shoot before you can launch an attack. This is one of the great truisms of warfare throughout history. The most powerful weapons ever developed mean absolutely nothing unless you know where to aim them.

In the void, finding an enemy that wants to hide can prove very difficult. It doesn’t matter if its a single ship or a fleet of thousands; against the scale of space both pale to equal insignificance in size. Think of how modern astronomers struggle to detect objects even kilometers across in our own solar system: over many nights of observations, pouring over readouts by hand or by computer looking for small glitches against the background stars that would point to movement. Now imagine trying to find something that size or smaller that’s trying its best to hide, and having to find it as quickly as possible before it kills you.

To make matters worse, while you’re trying to find your foe, he’s trying to find you. Obviously, the side which finds its target first while remaining hidden themselves will gain a great tactical advantage over the other. This is why sensors and intelligence are so important in this theater of warfare, even more so than for any other. If all else is equal, a ship with mediocre weapons and highly advanced sensors is more likely to emerge victorious against a ship with insanely powerful weapons and primitive sensors.

Battles in deep space will most likely take on a cat-and-mouse feel, with both sides hunting for each other across the immense nothingness while at the same time trying to hide themselves. Passive sensing systems, like thermal scanners, broad-spectrum electromagnetic sensors, neutrino detectors, and mass detectors would sweep through slice after slice of the Great Dark, looking for anomalies that could point to an enemy ship. Active sensors such as radar and ladar may only be used when a ship is already revealed and it has nothing more to gain by remaining stealthy.

Complicating this is the fact that while space is mostly devoid of matter, it is seething with radiation. While the enemy ship will most likely be emitting heat and electromagnetic radiation, the main trick is trying to distinguish it from the background. Ships may try to further stealth themselves by blocking or masking their radiative signatures. So forget about space warships gleaming with silvery hulls and bristling with big pointy guns; space-borne battlecraft will more likely be matte-black and have oblique-angled hulls to deflect radar and other active sensors. All the better to blend into the void.

A historic parallel to this type of conflict does exist: submarine warfare. In fact, many scenes in submarine movies that show the action on the bridge--of many sensor operators working in close clusters, of them calling out new contacts and status reports--can easily be reimagined as the reality on a space-going battleship. However, there are very few actual representations of this realistic approach to space combat in on-screen science fiction.

VOLLEYS ACROSS THE VOID

In any number of on-screen science fiction sagas, once the enemy is detected, ships will scream at full power to within visual range of each other in order to use weapons of equally limited reach. This makes for great visual drama, but is it really the smartest course of action?

Closing the distance means using the ship’s main engines extensively, which will blaze in the enemy’s sensors like a star. Also, one wants to question the wisdom of needlessly placing oneself at point-blank range of all the enemy’s guns. For most types of feasible space drives, reaching the target may take many hours or even days at full thrust, a heck of a long time to leave your ship vulnerable to easy detection and counterattack.

If you can hit the enemy at a distance without exposing yourself for too long, all the better. Again, the parallel to classic submarine warfare rears its head. A WWII era submarine would surface, launch its torpedoes, then quickly slink back under the waves, to maneuver around without detection for the next attack. Here, a ship will ping its target with active sensors for a quick sensor lock, fire its weapons, then quickly go back into stealth mode to cloak itself in the deeps of the void.

Once you know where your enemy is, you have to hit him. Given the distances involved, you will need weapons that can travel thousands or millions of kilometers and still do significant damage.

Missiles and drones will most likely be of more practicality than direct-fire beam weapons. Though some beam weapons can be propagated to reach that far and still do damage, one still has to deal with the major problem of precision fire control. Shooting a target from a million miles distance would require targeting accuracy on the par of a sharpshooter hitting a flea from orbit. Since beam weapon systems with the power to cover the ranges needed will most likely be immense, getting such huge machinery to make the minute movements necessary for such greater-than-pinpoint-accuracy would prove a major engineering feat.

A detailed discussion of specific weapon systems will be included in Part Two of this article.

THE BEST DEFENSE IS A GOOD ENGINE

After sensors, drives are the second most important aspect of deep space combat. Like in most other types of armed conflicts, how fast you can move and maneuver will often mean the difference between life and death. Again, the mightiest weapons in the universe don’t mean anything unless they can hit their target. The faster you can move the harder it will be for the enemy to hit you, and the more quickly you will be able to bring your primary weapon systems to bear on the target.

Of course, speed has its problems too. Most feasible types of space drives sport engine exhaust that can glow like a star to an enemy’s sensors. In the seek and detect phase of a battle, main engines may be used sparingly, if at all, lest one tips the enemy to one’s current location.

But once it becomes apparent that you’ve been found, either by the enemy using active sensors to pinpoint you or by detecting incoming ordinance zeroing in on your position, engine power and your ability to become a moving target becomes paramount. The idea perpetuated by on-screen science fiction that two capital ships would just float in one spot and slug it out is ludicrous. Why take the shot when you can move out of its way altogether? In three-dimensional space there are many more options for maneuvering than on a planetary surface, making vessels with good engines far more "slippery" and difficult to hit than slower-moving ships.

SPACE DRIVES AND COMBAT

Because engine power is so important, a brief list of the types of probable space drives and their effect on combat is provided below. More detailed descriptions of these technologies can be found in the links at the end of this article.

Chemical Rockets: Enormous fuel requirements, relative unreliability, and short endurance make these engines impractical for a ship’s main drive. However, they are useful for short bursts of high acceleration, making them practical as engines for short-range missiles.

Ion Engines: Large arrays of ion engines make for a very fuel-efficient, long-endurance space drive, but one capable only of very modest accelerations compared to other drives. However, while their exhaust is still hot (Ion Engines currently used on space probes have exhaust temperatures of about 300 degrees C) it is colder than the thousands of degrees of most other types of rocket exhaust, and thus would be harder to detect by a distant enemy. This makes them useful to a ship, missile, or drone that wants to maneuver about with minimal chances of discovery. A ship may have another type of drive for normal operations, and specialized ion engines for stealth maneuvers.

Plasma, Nuclear, and Antimatter Rockets: Much more fuel efficient than chemical rockets and capable of much more powerful accelerations, these are probably the drives of choice for any ship in the midst of an ongoing space battle. Their exhaust in highly energetic and often radioactive, making it near-impossible to miss a ship equipped with one of these drives even millions of kilometers off. However, this type of rocket exhaust also remains dangerous and radioactive many kilometers behind the ship, making it potentially useful as a possible short-range defensive weapon.

Bussard Ramjet: Theoretically capable of near-light speed, this very powerful drive also employs a potent magnetic field scoop that can extend for tens of thousands of kilometers ahead of the ship. This scoop field is powerful enough to be used as a weapon, potentially destroying any electronics, computers, and unshielded living organisms it encounters. As the ramjet is basically a highly advanced fusion rocket, its exhaust also has potential defensive weapon use.

THE MYTH OF THE SPACE FIGHTER

Fighter aircraft are a long-standing mainstay of today’s armed forces, harking back to the era of the first World War. In an atmosphere, it makes sense that smaller craft are faster and more maneuverable; both gravity and air resistance work against larger craft.

However, in space, neither of these are a factor. In fact, capital ships in science fiction are often shown as having enormous engines well in keeping with their scale. Yet if their engines are larger and far more powerful than that of the smaller ships, why are they always portrayed as much slower and more ponderous than the supposedly quick and nimble fighters? Think of a model airplane and a real, full-scale prop-driven aircraft. Both use propeller-driven engines to fly, but there's no question which one would win a side-by-side race.

Engine power plays far more important a role in spacecraft speed than the size of the ship. Assuming an equal level of technology, since the larger ships have larger and more powerful engines, its logical to conclude that they would be capable of far greater speed and acceleration than smaller vessels.

In other words, those Imperial Star Destroyers should have been zipping past the TIE fighters, not the other way around!

While smaller vessels would have some maneuverability advantages such as tighter turning radii, a ship with a bigger engine can move faster, and thus would be less likely to be hit in battle.

Fighters also require a cockpit, a manual control surface, and life support for the human pilot. Since the fighter could spend hours or days en route to the target, the life support systems would have be fairly extensive. Fighters in addition need special, pressurized bays for access and maintenance. Lastly, in order to preserve the pilot, accelerations will have to be limited to what humans can endure.

Missiles and drones have no such limitations. They can accelerate at hundreds or even thousands of g's, depending on how they're designed. Without the bulky life support systems or the need for a human pilot they can be made smaller, more cheaply, can be stored on board in greater numbers, and deployed much faster. And, of course, missiles are expendable.

But perhaps most significantly, human pilots will not be able to match the split-second, minutely-calibrated course corrections and targeting resolutions advanced artificial intelligences would be capable of making many times a second. If a civilization is advanced enough that deep space travel is an everyday occurrence, it should be safe to assume that their computer systems would reach a point where they could outperform any human pilot.

Manned space fighters, while embodying much of the romance of the classic space opera, would prove imminently outmatched on all counts by the larger, faster battleships and their cheaper, more numerous, and far more capable AI missiles.

This is not to say that manned subcraft would have no place in space conflicts. The _Traveller_ RPG contemplated the existence of battle riders, enormous capital ships that would house the bulk of an interstellar drive and act as carriers for smaller ships which would not have to worry about housing such systems. But these subcraft would be fully-equipped battleships in their own right, not skimpy pseudo-aircraft. And as it is assumed here humans will make most of the strategic and broad tactical decisions, a ship may deploy a heavily-stealthed manned subcraft to direct a fleet of drones or missiles in one area of the battle while the main ship departs for another.

LIGHTSPEED LAGS

If multiple ships are deployed by the same side, we run into another major hurdle of space combat: communication and sensor lags dictated by the speed of light. Ships in a single battle group may be deployed many millions of kilometers apart, resulting in communication delays that could stretch minutes or even hours. This makes coordinating efforts among major battle elements problematic at best.

Of course, communications lags were a common hurdle to most armed conflict before the Twentieth Century, and can be handled much the same way. Individual ships must be allowed a great deal of flexibility and autonomy, with a pre-established doctrine to follow in most foreseeable circumstances.

However, this communications lag combined with the supreme need for stealth in space combat can lead to problems, not the least of which is trying to distinguish a potential enemy from an ally in the heat of battle. Tightbeam radio communication can help with this, but there is the problem of signal leakage and losing track of a friendly due to unexpected maneuvering.

Lightspeed lag also plays a major role in hunting for an enemy. When one finds an enemy ship, the data of its position may already be seconds, if not minutes, old. Rather than pinpointing where a ship is, usually the best scanner operators can give is where the ship was and probabilities of where the ship went after that. In other words, when you are plotting a targeting solution to fire your weapons, you are aiming at a sphere of possible ship positions as opposed the actual ship itself.

RACING RELATIVITY

Combat at near-light speeds carries a number of special challenges. Relativistic effects can greatly alter the nature of a conflict.

As speed carries so much importance in combat, ships will edge as close to lightspeed as possible, if they have the capability to do so. However, the closer one gets to the velocity of light, the more the phenomenon of time dilation asserts itself. Those ship moving at significant fractions of lightspeed will experience the passage of time at a much slower pace than those moving at more normal speeds, creating even more of an information lag between attacker and target and much more difficult time coordinating among fleet elements. Calculating and compensating for the differing temporal frames of reference would have to become essential to ships capable of near-luminal speed.

Also, relativistic effects can also greatly extend the length of a battle. At large fractions of lightspeed, millions of miles can be eaten away quickly, lightspeed lags mount up, and time-dilation can stretch a battle significantly to those observing it from a "normal" frame of reference. Stories by both Larry Niven and Stephen Baxter have explored this situation in the extreme, as combatants chased each other across the galaxy and engaged each other at speeds at hairbreadth’s away from the velocity of light. These battles spanned tens of thousands of years, outlasting the civilizations that originally built the ships, yet to the crews only weeks had gone by.

GRADING SCI-FI SPACE COMBAT

Now that we know more about how warfare in space will be fought, how do various science fiction properties compare? The following is a brief summary of how realistically or not science fiction shows portray space combat. This is NOT a reflection of their overall entertainment or storytelling quality, but simply a brief technical analysis.

Star Wars, et al: Grade: D-. Basically WWII naval combat taken to space. Exhilarating to watch, but ultimately unrealistic.

Stargate: SG-1: Grade: D-. Large non-moving capital ships slugging it out at eyeball-range.

Battlestar Galactica (classic): Grade: F. Based on the _Star Wars_ model with even worse science. I haven’t seen the newer version, so I can’t comment on it.

Star Trek (original series): Grade: C. Given its advanced technical assumptions (ships moving at significant fractions of lightspeed, shooting at each other across thousands of kilometers) it actually portrayed battles semi-realistically despite (or perhaps thanks to) its more primitive special effects.

Star Trek (TNG): Grade: D. Capital ships just sat on screen exchanging shots. Does get some points for some episodes that harken back to the original series model, plus important role of ship detection and sensors.

Star Trek (later series): Grade: C-. The capital ships begin to _move_, at least in most cases. But except for a few tantalizing examples (the _Voyager_ episode "Equinox") the franchise is still mired too much in the _Star Wars_ model.

Andromeda: Grade: B. Semi-realistic given its superscience technical assumptions. Ranges are measured in light-seconds, missiles and projectiles are used for long-range shots, sensors play important role. Loses some points for overdependence on manned fighters in later episodes.

Babylon 5: Grade: C. Space combat based largely on the _Star Wars_ model, but stuck somewhat more closely to realistic technical assumptions. Loses points for too many eyeball-range battles, dependence on manned fighters.

Farscape: Grade: -. I’ve only seen a few episodes of this series, so I can’t judge it fairly.

GRADE A’s

So are there any science fiction sources that portray deep space combat well? There are a few, listed below:

The Traveller RPG: The source that best represents realistic space combat is not found on-screen or even in novels, but in one of the seminal table-top role-playing and strategy games. Earlier editions of the _Traveller_ RPG in particular took the sheer immensity of space seriously and even had vector-based movement for its tactical spacecraft simulations. Even though the game borrowed much of its ship design philosophy from _Star Wars_, space combat was fought over many game-hours or days, as the vessels hunted for each other across tens of thousands of kilometers of void, desperate to get the first weapons-lock. _High Guard_, the original space-combat expansion for the game and now well over twenty years old, still stands as the hard SF fan’s definitive view of ‘realistic’ space combat.

Orion’s Arm: An online shared worldbuilding and creative writing project, this hard science approach to far future science fiction contains very well-thought out essays on the nature of future warfare.

Known Space: This series of stories and novels set in Larry Niven’s vivid future history (including the more recent _Man-Kzin Wars_ anthologies) portrayed its many deep space battles realistically.

A Fire Upon The Deep and _A Deepness In The Sky_ by Vernor Vinge: These related novels both showed a grasp of the complexity and scale required for deep-space battles, especially harrowing conflicts fought with swarms of missiles and drones.

Singularity Sky by Charles Stross: One of the most hard-science looks at space warfare, as a human fleet attempts to take on a post-Singularity civilization.

CONCLUSIONS

As humanity moves out into the universe, we will take our nobility, our curiosity, our courage with us. But so too will we take our capacity for war and destruction.

Space offers a battlefield unlike any in history, with unique obstacles that will challenge the utmost of human ingenuity. Rather than blazing beams and swooping dive-bombers, victory in such an environment will instead depend much more on stealth, cunning, and smart tactics.

FURTHER READING

In Print:

The Writer’s Guide to Creating a Science Fiction Universe, by George Ochoa and Jeffrey Osier

On The Web:

Spacedrives

In Part One of this article, we examined the environment of space as a battlefield and the tactics a space-borne warship will need to succeed there. In this part, we'll take a look at the weapon systems that will be needed in this new theater of war.

We've already established that war in space will encompass vast distances heretofore never before encountered by any military force. Space-going warships will have to hunt for each other across vast deeps of nothingness, and be forced to engage the enemy at distances of many thousands or even millions of kilometers. But what kind of weapons can travel, much less hit and do damage to a target, from such immense ranges?

MISSILES

The oldest space technology may well prove to be the most effective space weapons. Essentially small spaceships in and of themselves, these advanced rockets would swarm across the void to attack an enemy ship en masse.

Missiles have a definitive advantage over beam weapons, in that they can track and home in on an enemy vessel no matter how the other ship maneuvers. Most beam weapons lose effectiveness and accuracy with range; a missile’s warhead can get in close to a ship and have a far greater potential for hitting and doing damage.

Missiles also need not be launched directly from the main ship. They can be "dropped off" into space while the main vessels maneuvers away, so that when their engines are ignited they will not give away the position of the ship.

The types of missile warhead that would be most effective in space combat is open for debate. Because of the vast scale involved, the presumed "slipperiness" of an enemy ship maneuvering at high velocity in three-dimensional space, and other defense measures the foe can take, direct-impact weapons are not a very practical consideration. The missile should instead carry a warhead that can damage the enemy from a moderate distance, which in space can range from several dozen to several hundred kilometers.

One obvious candidate is a nuclear warhead, the more powerful the better, to propel thousands of high-density, high-speed shrapnel fragments from a specially-designed casing at the enemy. Assuming at least a 1-megaton blast, the nuke’s heat and radiation flash, electromagnetic pulse, and hyper-velocity projectiles could prove to be a very deadly combination for any spaceship even dozens of kilometers away. Far more powerful warheads with much larger danger zones may be desirable, and research has shown that it is possible to tamp nukes to direct over half of the bomb’s energy in the enemy’s general direction.

It should be noted that one thing that a nuke in space will not produce is a significantly powerful shockwave. Shockwaves on the surface of Earth are propagated by the atmosphere; in space only the shockwave produced by the vaporized bomb casing would be felt, and at typical space-engagement distances its impact on a ship would be negligible. However, without the atmosphere to absorb all that excess energy, both the heat and radiation flash of the bomb would prove much more lethal at much greater distances.

Another possibility is to use a nuclear detonation to propagate one or more a powerful X-ray lasers at a target. This technique was researched extensively during the SDI effort in the 1980s, and though it proved unworkable with current technology, the theory is still sound and could be made to work in the future. Unlike shrapnel-propelling warheads, nuke-propagated x-ray lasers would be able to deliver far more of the warhead’s energy to the target. Depending on how powerful the originating blast is, they could also hit from much farther away, perhaps up to several thousand kilometers distant.

Explosions using matter/antimatter annihilation should also be considered. This is the base technology behind _Star Trek's_ famed photon torpedoes. Matter/antimatter explosions can deliver far more potent detonations per gram of reaction mass than any conventional or nuclear explosive.

Of course, given the presumed velocity differences of the missile and its target, an explosive warhead may be superfluous. A missile may be assumed to be able to overtake its target with sheer velocity, as vessels with human crews would be limited to accelerations humans could tolerate, whereas missiles would have no such limitations. Once close enough the missile could just use a conventional explosion to break itself apart and hit the enemy ship with a spray of hypervelocity shrapnel much like an enormous shotgun blast. At typical relative space velocities of dozens miles per second or greater, that would be more than enough to shred most hull materials.

Highly advanced civilizations may also use missiles to deliver payloads of nanotech weaponry, particularly self-replicating microbe-sized robots called nanites that could disassemble enemy ships molecule by molecule. In Charles Stross' novel _Singularity Sky_, advanced AI missiles launched billions of such nanites at enemy ships in a wide-angled spray, each nanite protected from the extreme velocity and impact by a sheath of molecule-thick artificial diamond.

DRONES

In space combat, the main difference between a missile and a drone is that missiles are expendable, while drones are meant to be recovered and reused if they survive a battle. General-purpose combat drones would basically be miniature automated battleships in their own right.

Drones have an obvious advantage in stealth-dependent combat such as space warfare. Prior to attacking a target, a ship may drop off one or more drones that can approach a suspected target from different angles, allowing a ship to initiate an attack remotely without directly giving away its position. Drones can also be used as supplementary scanners, sweeping a suspected area at angles the main ship can't cover by itself. And if the ship needs to engage active sensors, it might be far safer to have a remote drone do so than the main ship.

Missiles, lasers, and particle accelerators would probably be the preferred types of offensive weapon for a drone for much the same reason they're the preferable weapons for a main warship. However, drones could also be used to employ more moderate-ranged weapons such as plasma guns and electromagnetic launchers against an enemy ship without having to risk the main ship getting in close to the target.

LASERS

A laser’s main advantage as an offensive weapon in space is its speed--moving at the velocity of light it can reach a target much faster than any other weapon. But lasers also have a major problem that’s rarely addressed in space operas: beam focusing. Though they are more tightly focused than any conventional beam of light, lasers suffer from the same phenomenon of beam spreading as any flashlight, only elongated over much larger distances.

How far a beam can travel before it spreads too far to be effective depends on its focusing diameter. The larger the focusing element, the easier it will be to concentrate a large amount of the laser's energy at a target from longer distances. Think of different sizes of magnifying glasses used to burn stuff under a hot sun; the smaller magnifying glasses must be brought much closer to the surface to be burned than the larger ones, because the larger ones have a much longer focal length.

An advanced laser with a beam diameter of a few centimeters will have a maximum effective range of a few kilometers. Lasers with beam diameters measured in meters (such as those researched for SDI applications) will have effective ranges of hundreds of kilometers. In order to reach a distance of, say, ten thousand kilometers--"close" range for typical space combat--the aperture on a visible light laser would have to measure thousands of meters across. This would preclude them from being used as offensive weapons by any but the most immense ships.

One way around the focusing aperture limitation is to employ very high frequency lasers, such as X-ray and Gamma-ray lasers, which would require much smaller focusing elements. However, these would present other problems, such as much larger power requirements and finding materials that can not only handle precision focusing of such ultra-high frequency light but that can also withstand the intense energies flowing through them.

Even so, offensive deep space lasers will prove to be enormous. One can imagine these huge laser systems being integrated exclusively as spinal mount weapons. Spinal mount weapons are a type of armament that runs the entire length of a ship; the rest of the vessel is literally built around the weapon system. The best known example in science fiction is probably the _Yamato_ and its "wave motion gun" from _Space Battleship Yamato_ (aka _Starblazers_ in the US.) However, in this case, the diameter of the beam-focusing elements would probably exceed the length of the rest of the weapon system, resulting in large disk-shaped ships. Think of vessels resembling large space-going spotlights and you'd have an idea of what spinal-mount laser weapon ships may look like.

Another way to extend the focusing range of a laser is to use a very special type of submunition--a drone or missile that can deploy a large focusing mirror. The drone would position itself between the ship and its target at an oblique angle, then deploy a quick-assembling mirror the originating ship can aim its laser at. The mirror reflects the incoming laser energy, re-focusing it at the target. To keep an enemy from using it on its attacker, the mirror can be made monochromatic to reflect just the one specific frequency of light employed by its makers. Given the extreme fluidity of space combat, chances are these reflecting mirrors could only be used once or twice before the target maneuvers out of the mirror’s effective focusing range.

Lasers would also have a secondary offensive use of being able to blind an enemy’s visual sensors, even at very long ranges where its ability to physically damage an enemy becomes nil.

PARTICLE BEAMS

Particle accelerators are a long-proven technology, sophisticated scientific instruments designed to plumb the depths of the quantum world. However, it has long been theorized that they could be used for offensive capabilities. Particle accelerators do not have to be ring-shaped, as they are in laboratories. They can be made linear and open at one end, allowing the particles to be accelerated to near-light speed along its length, then shot out the open aperture. This is the basis for particle beam weaponry found in great many science fiction sources, including the phasers from _Star Trek_ and the disintegrators from _Forbidden Planet_.

As with lasers, their main advantage in a space battle is speed--particle beams typically would travel just below the velocity of light.

Particle beams come in two broad varieties: charged and neutral. Charged particle beams work well for operations within an atmosphere where the charged particles moving in a single direction will create a loose current through the air, generating a magnetic field which "pinches" together the beam. Lightning, which is composed of electrons, works loosely on the same principle. But in space this represents a very serious problem, as without this air-circuit effect to hold them together, the like-charged particles will repel each other, assuring the beam quickly flies apart.

In space, neutral particle beams would have to be the rule in order to reach beyond a few kilometers. However, as its much easier to accelerate charged particles via magnetic and electrical fields, the necessity of a charged-particle accelerator with a "neutralizer" on its open end becomes apparent. This can take the form of a screen, a layer of gas, or an intersecting electron beam to render the charged particles neutral.

Because they are essentially firing physical objects, albeit very, very tiny ones, particle beams do not quite have the same problem of beam spreading as lasers do. Ranges of hundreds of thousands of kilometers are achievable with foreseeably advanced technology. Particle velocity is a much more substantial factor for delivering damage to a target. The closer the weapon can push the particles in the beam to lightspeed, the more energy they will have and the more effective they will be upon striking the target. For a particle accelerator, this means a longer barrel lengths for increased electromagnetic acceleration, with spinal-mount weapons being a natural outgrowth of such a progression. Whereas spinal-mount laser weapon ships would resemble huge, wide spotlights, a spinal-mount particle accelerator ship would be long and thin, resembling enormous rifle barrels.

MESON GUNS

A specialized type of particle beam first postulated in the _Traveller_ RPG universe is the meson gun. Pi neutral mesons (created by the collision of an electron and a positron) are subatomic particles that pass through normal matter with very little interaction, similar to neutrinos. However, the also have a very short life, decaying with a burst of gamma rays, which reacts much more substantially with material substances. A meson gun accelerates pi neutral meson particles to near-lights speed, where time dilation slows their rate of decay. If done with precision, the mesons can be timed to decay at a predetermined spot, and if packed densely enough in the beam they can unleash a tremendous amount of energy, approaching the level of nuclear bombs.

Mesons guns are a technology that require a very advanced degree of sophistication in all its elements, as the weapon has to accelerate the pi neutral mesons to within the right tiny window of near-lightspeed to delay their decay until they are passing through or near the desired target. They do have a very unique property of being able to be fired _through_ physical objects without harming or even interacting with them in any way. They can bypass defenses such as sandcasters clouds, magnetic fields, and armor easily. In fact, a ship equipped with a sufficiently powerful meson gun could theoretically fire completely through a planet to hit a target on the other side.

DEFENSIVE WEAPONS

With missiles, drones, and shrapnel from explosions being such a major factor in most space battles, the need to intercept and destroy these potential threats before they reach the ship becomes paramount. This is a part of space combat the _Star Wars_ film series, which I perhaps disparaged a bit unfairly in Part One of this article, did get right--the need for large arrays of medium and short-range weapons to take care of incoming threats.

However, even "close" range in space combat--the minimal distance for missiles to detonate with an almost certainty of its shrapnel hitting the target--can be measured in dozens of kilometers, meaning that the target will still be well beyond visual range. Add to this that the targets will be moving at relative speeds of at least dozens of miles per second, and one can see how useless human-controlled gunnery like that on the _Millenium Falcon_ would be. Almost all defensive gunnery would be handled by computer, which could track and target much faster and much more effectively than any flesh and blood gunner. However, specialized officers may still be needed to oversee the system as a whole in order to make broad tactical decisions.

At medium ranges, defensive tactics would use targeted weapons as much as possible, to take out incoming missiles and drones. Close in, tactics change, dominated by dispersed particle throwers, beams, and fields to throw off incoming shrapnel from detonated warheads or weaken beam weapons from farther off.

Close-in defensive tactics would be aimed much more at deflecting as opposed to outrightly destroying incoming shrapnel. As any boxer or martial artist can tell you, deflecting an incoming punch away from you takes far less effort than stopping it dead, and the same principle would apply here. Because of the distances involved and the speed the ship is travelling, even a tiny change in the direction or velocity of incoming shrapnel will likely prevent a hit altogether.

MISSILES

Defensive missiles are an already a known if underdeveloped technology, the most famous being the Patriot anti-missile system used during the Gulf War. A defensive missile would scream into the void, max out its velocity in relation to its target, then explode, meeting the incoming threat with a high-velocity, rapidly-expanding shower of shrapnel.

Nuclear weapons, even small ones, would likely not be used in defensive missiles not because of the potential damage to the ship (typical distances to target and tamped detonations would prevent that) but because nearby nuclear explosions would temporarily blind the sensors of the ship.

DRONES

Defensive drones would most likely be decoys, deployed alongside and copying the sensor signature of the main ship to draw fire at critical moments. Its assumed at the technological level required for routine deep space travel an AI missile would be able to easily distinguish between a real ship and a "dumb" decoy like a flare, so a defensive drone would not only have to mimic the main ship’s electromagnetic signature, but be able to maneuver around and put up at least some defensive fire like a real ship.

LASERS

Lasers truly come into their own when used defensively. Like in _Star Wars_, ships may have large batteries of laser turrets. Remember that realistic combat lasers won’t be the pencil-thin beams of science fiction. Beams up to several meters wide, like large spotlights, could quickly pan across large swaths of the sky, using their energies to not only target incoming bogeys but to also deflect much nearer dangerous shrapnel.

Relatively low-powered lasers can also be used to ionize threatening debris, allowing it to be more readily deflected by a defensive magnetic field (see below.)

PARTICLE BEAMS

Scaled-down, turreted particle beams can be used as defensive weapons to target incoming missiles and drones. However, unlike lasers, their use very close in is dubious.

PLASMA GUNS

Plasma weapons can be devastating short-range weapons, with larger guns having estimated effective ranges of several hundred kilometers.

Take a volume of hydrogen, superheat it to a plasma state in a magnetic bottle, then collapse the containing field rapidly so the plasma is compressed into a high pressure jet that's expelled from the weapon at high velocity. The energy weapons in the _Star Wars_ movies, despite various descriptions down through the years as lasers and particle beams and "photonic bursts," most closely resemble plasma guns in look and effect.

At effective ranges, plasma weapons can deliver both thermal damage measured in tens of thousands of degrees as well as kinetic energy damage as the high-velocity plasma impacts the enemy's hull.

These weapons do have drawbacks, however. Plasma is very energetic and chaotic, and despite leaving the weapon as a tight stream, it eventually spreads out quickly and flies apart. There's also the problem of entropic heat loss of the plasma stream as it moves through hundreds of miles of vacuum.

To offset these problems and maximize its potential range, the velocity of the plasma as it leaves the weapon is crucial. The higher a plasma bolt's speed, the farther it can travel before the chaotic dynamics of the plasma makes it ineffective. Both ultra-high pressures used to collapse the plasma as well as an array of accelerating electromagnets along the barrel can maximize a plasma bolt's velocity and potential damage.

ELECTROMAGNETIC LAUNCHERS

Electromagnetic launchers (EML's) accelerate a projectile using magnetic fields generators arrayed along the length of a barrel. The two most popular schemes involve either using a powerful current running along two charged rails with a projectile between them, or a series of coil magnets to propel a suspended bullet. In real world tests, the railgun configuration has proven problematic, as the rails tend to deform after only a few shots, and the coil gun configuration, while much more dependable, is harder to engineer. Research is continuing on both types of weapons.

As there is very little friction, EMLs are capable of launching many small projectiles at very high speed in rapid succession. EMLs can ensure covering a large area with disabling shrapnel in only a few seconds to take out incoming missiles and drones.

Large EMLs can also double as missile launchers, to give missiles an extra boost of velocity leaving the ship.

Unfortunately, though effective against short-range targets, EML projectiles would be far too slow and lack a missile's maneuverability to make them effective as long-range weapons.

SANDCASTERS

These defensive weapons have had numerous incarnations from many different sources, but the principle is basically the same. Sandcasters throw out large clouds of particulate of one kind or another (actual sand has been quoted because of its assumed cheapness to obtain, but tiny ball bearings, water droplets, and dust have been mentioned in various sources) around the ship. Because of the huge relative velocity differences in space combat, even small grains of sand would impact incoming threats like high-powered bullets.

Sandcaster magazines would basically be comprised of large canisters filled with particulate, whose contents are shot out into space and immediately dispersed in an outward-bound cloud. As these are relatively low velocity, low range weapons, sandcasters are usually the defensive measure of last resort, a Hail-Mary cloud of particles used to stop or deflect incoming shrapnel. They're also of some use against beam weapons as they create an obscuring cloud that can weaken or perhaps even deflect an incoming beam. A sandcaster's cloud of expanding particles can also help obscure a ship's sensor signature, helping to prevent precise target locks.

Some sources have also suggested making the "sand" magnetically charged and using a small drone subunit with a powerful magnetic field to shape the sand into different configurations for different purposes. If trying to deflect incoming shrapnel, for instance, arranging the particulate into expanding layers would be more effective than just a random cloud. Also, if one can anticipate having to defend against laser weapons, the particles in the cloud can be specifically made light-reflective.

MAGNETIC FIELDS

Powerful magnetic fields were the original concept behind the term "force field", i.e., a field of electromagnetic force. Basically, the ship generates a very powerful field around itself, helping to deflect incoming objects and beam weapons. The simplest way of doing this would with large amounts of superconductive wire arrayed in a grid around the outer hull.

Unfortunately, in order to be effective, such a field would have to be many, many times the strength of Earth's magnetic field, so much so that exposing humans to it would be fatal. The ship would need heavy shielding, not so much for combat but to protect its human operators from the effects of its own defensive field.

ELECTROSTATIC DEFENSE FIELD

A defense originally conceived for armored ground vehicles, a scaled-up version of this could also help a spaceship defeat incoming physical threats. Large capacitors on board would build up and store a tremendous amount of electrical charge, which can be routed to conductive grids on the outer hull of the spacecraft. The ship projects a weak electromagnetic field around itself. Any physical object entering this field would become instantly charged, allowing an open circuit to be formed with the ship's capacitors. From an observer outside, it would look very much as if a bolt of lightning lanced outward from the ship to incinerate the incoming threat.

The system would be set up so that it would activate automatically to intercept anything of significant size entering the triggering field. Even though in typical space combat the ship would be expected to be hit by hypervelocity shrapnel as opposed to large projectiles, given the enormous scale of the battle field, even a ship a kilometer across would typically not encounter more than a handful of shrapnel fragments from any one explosion. (That’s right--all those sandcasters and defensive missiles and whatnot would be trying to stop a handful of fragments at most--but remember, even one impact at those velocities could severely damage the entire ship.) A ship would typically carry multiple high power capacitors to handle incoming multiple threats, each being activated in quick succession as needed.

CLOSING THOUGHTS

As we’ve seen in both parts of this article, battles in deep space will be like nothing we’ve yet seen on screen. They will, in fact, be far more terrifying. Imagine crews huddling around sensor readouts and pouring over computer analyses for days, trying to find that near-inconsequential anomaly that could point to an enemy ship. Their deaths may have already been launched days ago, streaking through the void to detonate at any second. To kill their mighty warship and end their lives with a single hyper-velocity missile fragment that may be no larger than a penny.

And on such small things, the fate of freedoms, peoples, worlds, and even entire civilizations may rest in the future.

Perhaps the coming centuries of space travel will be ones of peaceful exploration and settlement. But really, given human nature, how likely is that? The real question is not _if_ war in space is inevitable, but only who will reap its terrible consequences.

FURTHER INFORMATION

In Print:

Fire, Fusion, and Steel: The Traveler Technical Architecture by Frank Chadwick and Dave Nilsen

On the Web: