Six Problems With Realistic Space Battles

Who doesn’t love giant space battles with lasers and missiles and shields, oh my? Communists, that’s who. From Battlestar Galactica to Deep Space Nine’s Dominion War, some of our most riveting science fiction has come from spaceships trying very hard to destroy each other. Unfortunately, things get complicated when you introduce real science into the equation, and not just because there’s no sound in a vacuum. Space is an alien environment, and it’s difficult for us puny humans to understand all the potential difficulties of fighting there. The issues are so numerous that it’s no wonder filmmakers keep going back to a futuristic World War II.

1. Space Is Really Big

Earth_to_Sun_-_en To quote the great Douglas Adams, “You just won’t believe how vastly hugely mindbogglingly big it is…” Models of the solar system don’t really do it justice. The distance between Earth and Pluto is about 53 times the distance between Earth and Mars. Objects in the asteroid belt are often millions of miles apart, and that’s considered densely packed in space. Instead of a Romulan warbird filling the viewscreen, enemy ships would appear as little more than blips on a radar display. Long range missiles and laser weapons would mean that the opposing sides would never get close enough to see each other.

While this can work pretty well in novels, it’s a major problem for visual mediums that depend on action packed dog fights to keep things interesting. What’s more, because space is so big, travel time can become a serious factor. In a lot of scifi franchises, travel is near-instantaneous due to fancy warp drives or what-have-you. In a more realistic world, getting from where you are to where the enemy is can take days or weeks, even with a relatively high level of technology.

2. Weapons Advance Faster Than Armor

Super Laser Fire The iconic image of two capital ships slugging it out broadside to broadside simply does not work in space, and that’s because neither vessel would be able to take more than one or two hits from the other. In real life, we are already at the point where a single missile can sink a large warship, and that curve is only going to get more pronounced with new technology. It turns out that destroying something is much easier than keeping it intact.

Throughout history, weapons have gotten progressively more destructive, and armor has been unable to keep up. Modern body armor can usually stop small arms fire, but it is absolutely useless against anything more powerful. Even heavily armored tanks can be easily destroyed by much less sophisticated weaponry. The reasons for this are pretty simple. Machines rely on moving parts – be they a heart and lungs, or a fuel injection system. A weapon doesn’t have to destroy the entire target. Just mess up a vital system, and suddenly the whole thing stops working. Armor has to protect an entire object, while a weapon only has to apply destructive energy to one part of it.

In space, no one will think twice about deploying nuclear missiles* and all the power they contain, to say nothing of all the new and interesting ways humans will surely think up to kill each other. Even energy shields don’t solve the problem in a realistic universe, because the amount of energy needed to run them would pale in comparison to how much energy a laser would need to punch through.

There is one possible method of effectively armoring space ships, but it almost never features in stories: make your ship out of an asteroid. It turns out that a thick layer of rock and dirt is very effective at stopping explosions, even nuclear ones. There’s a reason bunkers are built underground. Of course, lumpy space rocks with engines welded on aren’t nearly as majestic as the USS Enterprise, which is probably why they don’t show up in science fiction very often.

3. Planetary Bombardment Is Really Easy

Meteor Crater We all know how unrealistic the Death Star is, but what if I told you it was also complete overkill? Wiping out all advanced life on a planet, while a monstrous act, isn’t that hard if you have some handy space rocks floating around. All the would-be mass murderer has to do is grab a good sized asteroid and accelerate it toward the planet in question, then lean back and let physics do the work. It turns out that humans, like dinosaurs, are highly susceptible to asteroid impacts.

Stopping an incoming asteroid from the ground is really hard, and there’s no reason the attackers couldn’t launch a few dozen at once just to keep things interesting. The same principle applies to space stations or any other object that can’t significantly alter its trajectory. Rather than massive fleets laying siege to defiant worlds, all it would take is a single ship threatening armageddon. By the same token, actually conquering a planet with ground troops would be insanely hard, but that’ll have to wait for another day.

4. Everything Happens Super Fast

HYPERDRIVE X-wings and Vipers might look like they’re speeding along, but it turns out they’ve got nothing on NASA. Back in 1969, the Apollo 10 spacecraft reached 24,791 mph, or about 32 times the speed of sound. Presumably, spaceships of the future will be even faster. They’ll have to be, because as was previously pointed out, space is really big. The problem is that humans simply cannot react at those speeds. Imagine yourself as a future gunner, trying to shoot at an enemy ship zipping by so fast that it’s gone before your brain has registered it was there.

To put this in perspective, the Komet rocket fighter flew at about 700 mph, and that was considered too fast for any practical fighting. The Komet would zoom past its targets so quickly that the pilot didn’t have time to shoot anything. Lasers go even faster; the speed of light, to be exact. Any ship under attack by laser weaponry would be hit at exactly the same time they realized they were being shot at. There would be no time for any dodging or weaving, no matter how good the pilot was.

5. Maneuvering Will Kill Your Crew

Bridge shake It turns out that going really fast in space isn’t a problem. Without air resistance, the speed of light is the only real limit out there. The problem is in how fast you accelerate. When a ship’s engines go to full burn, the crew are going to be pushed really hard into their seats. Human beings can only withstand so many gs,* and it gets worse the longer we have to sustain the pressure.

Combat maneuvers don’t have the luxury of slowly building up speed. When enemy missiles come burning in, you have to get out of the way fast, and that sort of violent movement will pose a real danger to your crew. Without magical devices like Star Trek’s inertial dampeners, sudden acceleration or deceleration can turn us fragile humans into pink smears on the back wall. The incoming ordinance doesn’t have the same biological restriction as a crewed ship, so avoiding it will be next to impossible. Sorry, Starbuck, but it turns out that Cylon missiles don’t have your fragile meat body problems.

6. Everything Should Be Done by Robots

Cylon Pilots Computers can process information much faster than humans, and that gap is only going to get wider as technology advances. Even the modern military is relying more and more on computers when human reaction time just isn’t fast enough. The Phalanx missile defense system, for example, uses automatic radar targeting, with no direct input from its human operator.

Even without the development of fully sapient artificial intelligence, computers are getting better and better at independent operation. What’s more, they can be built to withstand far greater strain than the human body. Also, computers don’t need to breathe. A hull breach matters a lot less when there’s no air to leak out, to say nothing of the space saved from not having toilets.

Fully automated warships would be able to react faster and be much better at surviving than any ship crewed by flesh and blood humans. Not only would realistic space battles consist of radar blips shooting at each other, humans would be confined to watching those blips from even farther away. Both sides would send out robot fleets, and then have to hope that their version of iTactics was more advanced than the other guy’s. Perhaps not as exciting as the Battle of Endor.


None of this is to say that realism can’t or shouldn’t be applied to space battles, just that it must be done carefully, because it will drastically affect the story. Battlestar Galactica solved the problems of distance and speed with a teleportation-style FTL drive that put opposing ships within spitting distance of each other. The Honor Harrington series builds drama around the long wait between firing off a salvo of missiles and when they finally hit their targets. Leviathan Wakes absolutely revels in the crushing gs caused by violent combat maneuvers. What’s important is that authors who want to write hard science fiction be aware of these problems, and either turn them into advantages, or make a conscious choice to ignore them. Believe it or not, you can still write hard scifi even if you have to fudge a detail here and there. You just have to know you’re doing it.

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  1. Hunter_Wolf

    Speaking of using astroids as ship hulls, i think the manga (now an anime as well) Knights of Sidonia has those, the massive ships the characters live on are basically built inside giant astroids, some of the weapons are also interesting, one time the ship uses a kinetic projectile launched from its main rail-gun (with a kilometers long barrel going along the axis of the ship) to destroy a giant alien colony, the projectile itself is in fact nothing more than a giant cylinderical lump of solid metal launched at a very high speed that it gains a lot of kinetic energy and as a result it becomes such a destructive fearsome force, it’s kinda like hurling giant astroids at stuff but more elegant, refined and controlled.

    Not only that but it also revels in the drastic effects of accelerating on the people aboard the ship, and even a slight change of direction while the ship is accelerating causes terrible things to happen, entire sections of the ship quarters get crushed under their own weight and the population on the ship have to use safety belts during those moments or get squashed by the extra gs like tomatoes aganist the inner walls of the ship, all this just because the ship changed its direction 5 degrees while accelerating to dodge an enemy projectile, these are some of the most tense moments in the show too.

    Knights of Sidonia one of the few sci-fi stories that found that brilliant balance between hard and soft sci-fi and used the realistic scinetific parts so well to create real tension and move the plot forward.

    • Oren Ashkenazi

      The Expanse also has some beautiful illustrations of the physics involved in space battles.

      • Hunter-Wolf

        Seems very interesting, will check it out, thanks for the recommendation.

    • Krssven

      Why is anyone on that ship in the first place, then? What the hell do they say to people when they board? ‘Sorry, if we have to do any unplanned manoeuvres there may be some slight discomfort as every bone in your body is shattered, but here is a free drink voucher and one free go on the roulette wheel’?

      Of course I’m being facetious, they don’t have any choice to be there. It’s still silly to have a ship that kills its crew/population just by slightly manoeuvring. It’s not like those people are going to be replaced. It’s an issue that was probably thrown in originally to make the physics appear more realistic, but in some settings, realism makes things a) boring as hell or b) really head-scratchingly stupid.

      • Meme Man

        I don’t remember too well since I haven’t been following Sidonia for a while, but I think there was some catastrophe on Earth involving the main antagonists that necessitated everyone evacuating in generation ships, so the dangerous conditions could be explained by them not having anything better at the time. But the design itself is pretty bad; the ship featured in the manga has a living region filled with ordinary-ish buildings with structure like you would find on Earth, so predictably any sudden maneuvers results in lots of damage to housing and the people inside. Maybe they did it to compromise for comfortability at some ship design committee? In any case they must have been expecting a fight, since the ship is armed, so there isn’t a good reason why it wouldn’t have been brought up to have more structurally-sound housing.

        There are worse problems with the setting though, like photosynthesizing humans.

        • Meme Man

          Forgot to mention, population instability is brought up in the story when there is exposition about how high deaths in some past event required genetic engineering and other biotechnology to bring the population back up. But that just brings up the plot hole of why they didn’t restructure the ship at that point, in addition to whatever other measures they were taking. They do some other new construction during the story, so there should have been enough resources to at least start building separate robust housing for people who prefer it.

  2. Krssven

    1) Space is really big, and that makes fighting at million-kilometre distances rather impractical. At millions of clicks your detection suites (even if they’re just radar) will see large ordnance coming long before it ever has any chance of hitting you. The main mistake here is assuming that we will have near- or at-lightspeed weaponry (lasers) and that these will somehow autohit from a range of (for example) 150 million kilometres. Since your uber-laser is based on light, even that distance will take EIGHT minutes to cross. This is more than enough time, even if you don’t know the hit is coming, to make a course correction. If you know the enemy blip is a certain distance from you, there is a LOT of time to make the tiniest of tiny move and the laser will miss every time. So by your logic, ships would be reduced to potshots from across entire orbits of distance, barraging an area that has a miniscule chance of even containing your enemy. This is all without even considering the defences that could be deployed if you know exactly where your enemy is. Guaranteed, if you know where they are, their slow-moving ordnance will be either shot down or also miss by stellar distances.

    This is the often-incorrectly ridiculed reason that shows such as Stargate and Star Trek had battles conducted at MAGNIFIED visual ranges. What is onscreen is unlikely to be the actual visual distance, which is confirmed when you realise that weapons in Star Trek were capable of shooting hundreds of thousands of kilometres. At those ranges it’s far more likely you will hit with a weapon that has a very fast projection/cycle time.

    2) Weapons do advance faster than ‘armour’ but in sci-fi we have to entertain that even in so-called realistic settings, your ship needs at least some modicum of defences. Because realistic battles will take place outside visual range (but measure in thousands rather than millions of km), you do need to be able to take a hit. It is possible for even a naval ship to survive multiple hits, but these are terrible analogies. Starships will be likely heavily armoured and hugely self-contained. Their command centres are likely to be in the centre to avoid fluke hits.

    Atomic weapons are of limited use in space. The damage is created in three ways:

    Blast pressure
    Radiation (mostly gamma)
    Direct heat

    Blast pressure is only generated by the atmosphere; in space, there is no blast from a nuke.
    Radiation is expected to be resisted sustainably in any space worthy/realistic ship, because space has a lot of radiation in it. If your crew is alive, you have to assume the ship is radiation proof.
    The radiative heat transfer from the nuke would be split between the impacted target and that directed away from the ship into space. The heat the ship absorbed could potentially cause a lot of damage, but not enough to destroy it, especially if the armour is designed to absorb it (remember those lasers you said were inevitable? Odds are, the armour would be designed to absorb high spikes in heat anyway). Even in Hiroshima, most metal objects survived, if not untouched.

    All of this misses one vital component of nuclear weapons: they are detonated above their targets. Nukes are not impact weapons like an armour-piercing shell or an anti-materiel round. They are designed to cause the highest destruction and death toll via heat, pressure and radiation. In space, that’s a big issue. Launching a nuke at a ship would require pinpoint accuracy and automatic trigger mechanisms, even to stand a chance of detonating near enough to cause enough damage. If the nuke actually HITS the ship, it risks damaging the equipment that starts the fission reaction in the first place. There’s also the small chance that the missile will get past any point defence the ship may have, which again is highly likely in any realistic sci-fi that uses nukes as its main weapons. Hell, even a spray of projectiles from a fighter or drone squadron would smash a nuclear missile. We’re doing that now!

    There is the additional danger of EMP, which is possibly the biggest threat to a non-hardened ship. But I would in any sci-fi setting assume EMP-protection is commonplace – we do this now too!.

    3) Planetary bombardment is really easy – in theory. A frequent mention on the internet is that ‘all’ you have to do is accelerate an asteroid to a portion of the speed of light and aim it at the planet. Why though? Throwing rocks into a planet’s gravity well is more than enough to devastate the surface; the impact that cause the extinction of the dinosaurs was cause by one asteroid that fell lazily into Earth’s gravity and hit it. The main issue with throwing rocks though is getting them there – if you assume the planet has defences, they may be more than enough to pop rocks into small enough chunks to do relatively little damage. Accelerating a round to to .5 C is a damn sight easier than an asteroid, and you’re assuming you won’t be coming under bombardment yourselves from the other side’s navy! If it doesn’t have a navy, then WHY throw asteroids at it?!

    4) Everything happens super fast for the person shooting at you, too. Conflicts begun and solved by humans will be conducted at human perceptive pace, otherwise no strategic decisions can be made. Since this is apparently realistic fiction, we can’t assume AIs and robots will be doing the shooting for us. At best it will be via some kind of drone warfare, but that’s a very dangerous assumption as most people predict the future by moving what we know into said future as if very little has changed. Look at how many sci-fi settings written in the 80s and 90s assume data would still be transferred via discs or tapes, and that even in the future power things would be charged by plugging them in. These things are different even 20-30 years later.

    5) This is a weird one, as to have any real motion or pace in a setting, you have to be able to go somewhere. Since ‘standard orbit’ means even a trip to Mars takes years, we have to make some assumptions here. There has to be some kind of inertial countering system or every single ‘realistic’ setting would go ‘set course for the next system! Everyone into the freezers, because this one will take 200 years!’ every single time anything happened. Films like Alien and Aliens (the only two films in that series :P) get around the problem by simply having plots that take place in one place over an extended period. It works, but won’t for every sci-fi setting that wants spaceships.

    6) This one is closest to being on the mark, but I’ve already covered why in the long-term robot fleets won’t work. First, it assumes your communication is realtime, unless these ‘robots’ are capable of making measured and independent tactical decisions like a human operator. AI is an incredibly difficult challenge and just because your phone can Google search for you doesn’t mean it is close to being hooked up to the decision-making end of a drone or warship. It’s insanely risky. What happens when the first mistake is made and a non-hostile ship is obliterated because the AI found it matched the hull configuration and registry of an enemy vessel? What happens when you are cut off from your robot fleet and can’t re-initialise communications? Pray that it hasn’t been virused and will smash your recovery ships as they get into range?

    Commander: ‘Where are our ships, son?’
    Operator: ‘Not there any more, sir.’
    Commander: ‘WHAT?!’
    Operator: ‘If they cracked our internal communications protocol, they might have been able to corrupt the control systems….’
    Commander: ‘So where are they?!’
    Operator: ‘Not sure, but the enemy probably has a few more ships now and…we probably have a few less.

    • vanguard103

      Great points man, I was wondering if you could give me any tips for my sci fi story. The basic idea includes aliens, angels, demons and space battles.

    • jediKnightmare

      those are some good points, but you forgot shields. Shields would make a huge difference when it comes to getting hit. Also if your trip took 200 years, by the time you got to the battlefield your ship could be way outdated and get totally obliterated.

    • DCMCO

      To my knowledge we currently have nuclear warheads designed to penetrate & defeat hardened Earth targets. I have not verified this calculation I found but: 4.184 terajoules per 1 kiloton of TNT -> Approximately 85 percent of the energy of a nuclear weapon produces air blast, shock waves and thermal energy. The remaining 15 percent of the energy is released as various type of nuclear radiation.

      The thermal energy is usually around 35% of the total energy released. A 100 kt nuclear explosion releases 116,222 MWh of energy of this 40,678 MWh is released as heat. That’s enough heat to melt 136,000 tons of steel. How massive was your spaceship? Was it constructed of unobtanium?

  3. vanguard103

    Great points man, I was wondering if you could give me any tips for my sci fi story. The basic idea includes aliens, angels, demons and space battles.

  4. JackbeThimble

    the example you gave of the HMS sheffield doesn’t actually prove your point. The Sheffield was destroyed so easily because it was a missile-age warship and thus had almost no armor. If it had been, for instance an Iowa class battleship it probably would have shrugged that hit off. You can’t use the destruction of an unarmored ship as proof that armor is useless.

    • El Suscriptor Justiciero

      > You can’t use the destruction of an unarmored ship as proof that armor is useless.

      In other words “a leather jacket can’t stop an arrow, that doesn’t mean plate armour is useless”.

  5. Eric

    Everything but the maneuverability part is correct. You have to burn the engines to change directions in space, and your ability to do so is limited by thermodynamics. Drives with low exhaust velocity are able to have the high thrust to perform high maneuvers but they have low delta-v. A high delta-v driverequires putting a lot of energy into a small amount of mass and pushing it out the back of the engines. This means large amounts of waste heat. Take a solid core fission thermal engine with an exhaust velocity of 8,000 m/s. It requires putting at least 32 million joules into each kilogram of exhaust at 100% efficiency which the 2nd law says that you can’t reach. A fusion rocket could have an exhaust velocity 1000 times higher at 8 million m/s. That is putting at least 32 trillion joules into each kilogram of exhaust. If the fusion rocket is as efficient as the fission rocket (it won’t be due to neutron and radiation loses), then it must have 1/1000th the thrust for the waste heat to be the same; but the fusion rocket can have a delta-v that is 1000 times as great for the same mass ratio. There is a trade-off between high exhaust velocity and high thrust. If you have a high delta-v drive, then your ship will be vaporized from waste heat long before g forces get a chance to kill a human crew.

  6. Dark Lord Thomas Pie

    What if the robots piloting the ship kept the people in charge/being transported inside of magical pods that keep them safe. Then they could maneuver the ship without anyone even NOTICING!

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