The Essence of Space Warfare

Children of a Dead Earth started with the question “What would space warfare actually be like?” The game itself is the answer to the question, but in this post, we’ll also go over the answer, based on how the simulation turned out.

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Head to head combat between two fleets of capital ships.

Modern warfare doctrines have very little on space warfare. There are a few public documents from the cold war era concerning satellite warfare, but they all hinge on several conceits that are not terribly relevant to full space warfare. In particular, they always assume Earth’s gravity and atmosphere as the main celestial body, and they assume that everything will stay in very low orbit, hugging Earth’s atmosphere. As a result, these doctrines are much closer to high altitude aerial warfare or ICBM warfare than actual space warfare.

There is always a tendency to want to take a certain kind of present day modern warfare and extrapolate it to space, or to try to find parallels. Would space warfare be similar to modern naval warfare, carriers launching fighters and bombers at each other, without ever seeing one another? Or perhaps like World War 2 fighter plane dog fights? Or maybe it would be similar to submarine warfare? Most soft science fiction takes this approach, but as it turns out, space warfare ends up being very dissimilar to all of these.

But there are similarities here and there.

For instance, the spacecraft sizes tend to be similar to modern naval carriers and destroyers. Yet, despite being similar sizes and masses, the masses distribution is radically different. An Arleigh Burke class guided missile destroyer masses at 9.80 metric kilotons, while a spacefaring Laser Frigate in Children of a Dead Earth masses at 7.71 metric kilotons, despite them both being 155m long. Whereas the majority of the missile destroyer’s mass comes from the hull, in space, the majority of the mass is in the propellant. This is due to the rocket equation, and the resulting need for extraordinary amounts of propellant to get any delta-v. Inside spacecrafts, it’s mostly just propellant tanks.

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The basic stats of a Laser Frigate, a medium-large warship. Space Shuttle Orbiter for scale.

Similarly, the carrier and fighter model of modern naval warfare also translates over to space warfare well. However, fighters become drones, entirely remotely operated on the carrier (this evolution is already starting to happen in present day US Military doctrine with UAVs). And another important weapon shows up, the missile salvo, an evolution of the modern ATGW or ASM. A spacecraft carrying 100 nuclear missiles is just as common as a spacecraft carrying 100 drones, and it serves its own unique combat purpose as well.

A surprising parallel is found with World War 1 battleships. As point defense technology evolves, drones and missiles no longer rule the battle space. Indeed, very recent examinations of modern US Naval doctrine have suggested that as point defense technology advances, we may see a resurgence of battleship warfare as point defense technology outpaces missile and drone attack capabilities. In game, point defense in the form of lasers and projectile weapons both are very effective at anti-missile and anti-drone warfare, yet both can be overwhelmed given large enough salvos of missiles or drones. As a result, if you’re weak on drones or missiles, getting in close with the capital ships themselves is a viable tactic. The advent of better and better projectile weapons seals the viability of this tactic.

But while there are plenty of parallels, there are far more differences unique to space warfare.

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A highly periodic orbit around Luna.

For one, simple movement in space requires understanding of orbital mechanics. Everything is always moving, relative to nearly everything else in space. You can’t stop in space unless you land on a celestial body, and doing so usually costs so much delta-v that’s it’s not an option. Going in depth into the orbital mechanics will be covered in another blog post, but one should know that it does yield counterintuitive results. For instance, if in the same orbit as a target, you will never get catch up to them, and you have to slow down to catch them, or speed up to let them catch you. This is because decelerating increases your orbital speed, and accelerating reduces your orbital speed.

One byproduct of these orbital mechanics is the speeds in space are truly enormous, far greater than anything you’ll ever see on Earth. Approaching your enemy at 5 kilometers per second (about 10 times faster than machine gun fire) is quite common. High speed warfare makes missiles deadly, as the time to respond with point defense drops down to seconds or less. At the same time, high speed combat allows one to dodge incredibly easily. A small nudge in any direction when the enemy is 100,000 kilometers away means your enemy will miss by kilometers. Despite the high speeds, combat can take place at very low speeds, and indeed, this is often desired for capital ship broadside warfare. Approaching an enemy moving 5 km/s relative to you and entering their exact orbit to yield a relative velocity of 0 km/s is completely doable.

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A gunship fires three different projectile weapons at an incoming salvo of missiles in the distance. Neptune in the background.

The scale and environment of space is unique as well. With no stealth in space, you will see your enemy half the solar system away, and you’ll be able to track their movements six months out or more. This makes surprise and deception nigh impossible in space, and warfare often comes down to nearly evenly matched fleets engaging in combat. With these enormous scales, skirmishes between two fleets in orbit around the same body may happen days or even weeks apart. For instance, two fleets in the same orbit, but one running retrograde, may experience five seconds of combat where the enemy zooms by at ridiculous speeds, and then ten days of downtime while the crew prepare for another five seconds of combat.

Delta-v, a measure of the total amount of velocity change one has, based on propellant left, is critical in space warfare. Capital ships tend to have much more delta-v than drones and missiles, but much lower acceleration. This means capital ships can dodge drone or missile intercepts by running them out of delta-v, and it makes for a very effective defensive strategy. On the other hand, if plotting one’s orbital mechanics cleverly, drones and missiles can still intercept capital ships using raw acceleration. Running enemy fleets out of delta-v is a very effective way to choose how pending battles will take place: at high speeds or low speeds, and where along their orbit.

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A shrapnel payload impacts the side of a spacecraft and detonates. Ceres in the background.

A final surprising effect is caused by the lack of atmosphere in space: explosions are pitifully weak. Without an atmosphere, conventional explosives simply blast a thin layer of gas on their targets, nuclear weapons are reduced to nothing more than glorified flash bulbs. Of course, the amount of light released by nuclear weapons is still great enough that they can melt through thick armor at very close ranges, so nuclear missiles are still viable for combat. But their effects fall off so quickly in space that they are almost contact weapons rather than area of effect weapons. If a salvo of nuclear missiles can connect with their target, though, they can be quite devastating. Conventional explosives also only tend to be effective when used to detonate a payload of shrapnel at high velocity at the target.

That’s a high level overview of how space warfare actually unfolds. Later posts will examine it closer, the actual technologies used in combat, and how engagements play out second by second.

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9 thoughts on “The Essence of Space Warfare

  1. I just started reading your blog, though I want to point out that there’s several background assumptions being made here that I’d call out: you seem to be assuming an interplanetary setting. It is completely possible that the fighting will be between two groups in close proximity to each other… and possibly far away from any major celestial body! Orbital mechanics will still be important but perhaps only on a long scale..

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    1. This is true. The game takes place entirely within the solar system, and mostly around planets, moons, and asteroids. The reason for this is that these bodies are where resources are going to be, and by extension where civilization, cities, space stations, and so on, will be located. It’s similar to naval warfare in World War II. In almost every naval battle between Japan and the US, the battle took place close to land. This is because you tend to use your forces to either attack important locations, or defend them. There was little point in attacking the enemy in the middle of the ocean, because you couldn’t acquire any resources or strongholds that way, and the enemy was free to retreat at any time.

      The same is true for space warfare. There are virtually no resources or strongholds in the emptiness of space, and if you do strike the enemy in the void, far from any celestial body, the losing side can just spend a little delta-v and evade quite easily. It makes much more sense for combat to take place mostly in low to high orbit around celestial bodies.

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  2. A thought struck me, as I was reading about missiles. Would bomb-pumped X-ray lasers be feasible? After all, research was done in the 80’s on it, though whether anything came of it is up in the air. In theoretical terms, a single nuke can power a number of lasing tubes, meaning that the resulting attack could be quite fiercely concentrated. As well, the stand-off capability would make it less vulnerable to point defense.

    Or is this one of those reasonable-sounding but actually ridiculous technologies that may show up one fine day in the fourth millennium?

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    1. Bomb-pumped X-ray lasers are not exactly fourth millennium technology, though they are a little far future for the game. I couldn’t find very much research on it beyond the cold war accounts, and very little specifics, and so I would have trouble implementing their details unless I wanted to just start making up stuff. It’s an interesting idea for sure, but I suspect the reason the research seems to be more or less abandoned is because certain feasibility issues cropped up that the engineers were unable to work around. The stated cause for Project Excalibur’s cancellation was the technology was too out of reach.

      I’ve noticed this a lot with technologies that try to harness nuclear detonations. Nearly every technology that has tried to control prompt criticality of nuclear detonations has failed to yield results. Nuclear bombs seem to be the exception, not the rule.

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  3. In one of your earlier posts you showed a ship damaged by a nuclear salvo that apparently melted some of the decks. Here you talk about the effect of a nuclear detonation on the target ship but not about the radiological effects on the crew. Would the crew even survive these nuclear detonations? Does the simulation take into consideration the effects of radiation on the crew?

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    1. Crew modules tend to have moderate radiation shielding (in addition to the reactor shielding) to guard against solar flares and nuclear detonation radiation. The end effects of this often end up being significant enough that the crew may need medical attention after getting salvoed by nukes, but not major enough that they will all die or that the crew module will be irradiated beyond use.

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  4. This is a less-than-combat question, but I can’t help but see it coming up in a real scenario – would we have situations like how F-15s and Typhoons wind up intercepting Russian Bears or off-course civilian planes? If so, are we talking long range, since you’d be out of the way of weapons but still able to inspect the ship? I kind of assume you’d sit nose toward the ship you’re intercepting, both to be protected from them and (in the case of civilian liners) avoid irradiating the people onboard with your engines.

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    1. Intercepting things in space ends up being very costly in terms of delta-v, though sending a missile or drone to intercept might be viable. In those cases though, you wouldn’t have to worry about irradiating people.

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