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PhD Candidate Talks About the Physics of Space Battles
darthvader100 writes "Gizmodo has run an article with some predictions on what future space battles will be like. The author brings up several theories on propulsion (and orbits), weapons (explosives, kinetic and laser), and design. Sounds like the ideal shape for spaceships will be spherical, like the one in the Hitchhiker's Guide movie."
That'll be boring: round ships, round planets, round explosions, and round movie goers.
Table-ized A.I.
"Sounds like the ideal shape for spaceships will be spherical, like the one in the Hitchhiker's Guide movie"
Or maybe like Doc Smith predicted in the Lensman Series?
emt 377 emt 4
that I've found thus far in her Merchanter / Alliance-Union books ---esp. Heavy Time / Hellburner --- though I'd be very interested in suggestions on other authors to read who've put forth a similar effort to have realistic physics and effects thereof.
William
Sphinx of black quartz, judge my vow.
When the future Enterprise flew at the other ship all perpendicular?! That was crazy.
The point that nukes wouldn't generally be useful is a good one. And the point that kinetic weapons would be ideal also makes sense. However, I'm not completely convinced by the emphasis on orbital mechanics. In order for that make sense, one needs space travel to be cheap enough and convenient enough that one can easily have lots of ships in space. If that's the case, one needs efficient enough propulsion systems that will make orbital mechanics not matter as much. They'll still matter probably (and certainly matter more than they do in standard scifi) but I'm not at all convinced they'll matter as much as he makes it out.
Also, he doesn't address the issue that long-range kinetic impactors can make most space combat irrelevant if they are going fast enough. There's not much Earth could do if there were large mass drivers on say Demos and Phobos sending fairly small projectiles at targets on the Moon or Earth or targeting large space installations. Again in this situation orbital mechanics would matter. But when the planets are in the correct positions, such setups would render local space combat irrelevant.
More powerful weapons, with greater range. Any direct hit with intended kind of weapon knocks out of the action at the least. Mostly only active countermeasures are effective, unless you can exploit the environment somehow or are good at camouflage. Never stay put. One big cat & mouse game. And so on.
The factors that shaped this will be even more pronounced in space, with the added fun of predicting position (speed of light limit). Which makes majority of SciFi depictions that more disappointing; limited in popular formats to somewhere between WW1 and WW2 state of affairs.
One that hath name thou can not otter
Assuming technology exists to accelerate space ships to interplanetarily practical speeds, what's to stop warring planets from accelerating an asteroid in the same way and in the direction of the enemy planet? Or take that acceleration technique and speed up some ball bearings to ridiculous speeds and send them on their way towards something with a predictable position like a space station? Hell, you could use millions of ball bearings like a mine field, because any ship traveling through the bearings will have such a high speed relative to them. I just wonder that if we currently get so butthurt about orbiting space debris, a space war will focus on simple kinetic weapons at huge speeds and from huge distances.
That assumes that there aren't technological advances that allow spacecraft to brute force the problem. Launch delays in terms of orbits mostly occur because of energy and fuel requirements. If you've got propulsion licked, you can pretty well launch when you wish.
That isn't going to work for stealth spacecraft which are a trivial engineering problem next to propulsion. Space is huge, you're going to need very very powerful sensors to find anything the size of a ship.
Correct. Burning fuel just to change the ships' direction is a waste. Utilising conservation of angualar momentum with a gyroscope is efficient and technologically feasible. Sapcecraft that are large and non-sperical are going to be very difficult to manoeuvre. Concentrating most of the ships mass in tight near the center is the way to mitigate this problem.
I don't think kinetic impactors are the way to go here. A high energy neutral particle beam is demonstrated to work effectively and doesn't spread out too much over a vast difference. (not more than a few cm over 1000 km) There is no hope of stopping it either. A few GEV beam of particles shows no mercy and can punch through several meters of shielding.
Lasers ablate material off the hull which obscures the target. Not quite the most effective weapon.
modified plasma window technology can function as a shield in a sense. Thick armor on the hull impedes the ship's ability to rotate.
Ammo is a problem. How many impactors can you have on an orbital defense platform? Just use particle beam technology to wipe out the ground force.
Only if you don't plan on re-entry as a sphere is non-optimal for utilising the effect that shaceship one was supposed to use; that is using a flat surface to force a ubble of air to pool in front of the craft and buffer against the heat.
Sigs are too short to say anything truly profound so read the above post instead.
Lasers lasers lasers! I'd imagine long distance battles (10's, 100's, 1000's of km) so anything traveling less than the speed of light would be horribly ineffective against evasive maneuvers.
And someone needs to invent something that makes laser pew pew sounds in the void of space!
They said this after the American Civil War. They said this after the first world war, the war to end all wars.... War will never end. "Let him who wishes for peace prepare for war" ~ Vegetius
the peace treaty was signed in december 1814. but a major battle in the war, the one that made andrew jackson's name, took place in new orleans AFTER the peace treaty. the combatants didn't hear about the peace until february 1815
http://en.wikipedia.org/wiki/Battle_of_New_Orleans
i think we'll see a return of that in space warfare. sure the wide open vacuum of space changes everything, but so does the sheer vastness of it all. in future space battles, it wouldn't be surprising for a peace to be signed, the agreement beamed to combatants at light speed... and yet the battle still rages on for weeks, months, maybe even years. the battlefield might be lightyears away from the capitols
i don't even know if the idea of central command will work. we're used to modern tom clancy style special operations nowadays where forces engage the enemy while analysts watch them in realtime in pentagon/ cia warrooms as infrared images on massive screens, caught from spy satellites high above
but you can't do that in space
so warfare in space will deevolve from this sort of highly vertically integrated command and control aspect. you can't, for example, have a commander on earth relaying instructions to his troops on mars in real time, simply because the radio signal takes 10-20 minutes, one way (depending upon orbital locations)
intellectual property law is philosophically incoherent. it is your moral duty to ignore it or sabotage it
There's little radiant thermal energy directly from a nuke, and even in the atmosphere where there's a lot more, a sheet of bright white posterboard would be 100% eccective as a defense. Drop and cover.
The energy directly from a nuke is mostly expresses as gamma and x-rays. These are planty damaging, but fall off with the square of distance. You'd need to get a pretty large nuke in pretty close to your target to produce more radiation than bad weather. Space this close to the Sun is harsh, radiation-wise.
So the solution is to use the energy of a nuke, but overcome the range^2 thing: nuke-pumped X-ray lasers. This is not a new idea - it's why Reagan's missile defense program was called "Star Wars". For all I know, we have this weapon in orbit already.
Socialism: a lie told by totalitarians and believed by fools.
They would be useful. Article is simply wrong. Sure, you don't have the shockwave but that much pure energy (even just the part that's shipward) would do a whole shitload of damage. You detonate the nuke when it hits the ship, I mean physically touches the ship. The ship will be destroyed. It's not like a ground based nuke where most damage comes from detonating in the air.
Sounds like the premise of Heinlein's "The Moon Is a Harsh Mistress". Revolutionaries on the Moon take control of a mass driver and start flinging multi-ton barges at Earth, with just enough remote-control maneuvering that the shooters can call up Earth afterward and ask if they'd like to surrender.
Revive the Constitution.
but aiming at something hundreds of miles away, moving at thousands of mph, the slightest vibration in the ship will send the beam several feet off course by the time it gets there. You won't be able to steadily drill a hole in the enemy ship, you'll just illuminate different parts of the hull w/o much heating or impacting any specific area.
The Airborn Laser program has to cope with the same problem, and shoot through an atmosphere. It's not that hard once you realize that you lens doesn't have to be made of glass. When you can change your lens geometry microsecond-by-microsecond, you can easily keep the beam on target over distances as short as hundreds of miles (and ever correct for atmospheric turbulance). If you dump enouh energy into the target it won't matter much that it's spead out a little. Of course, you want your laser to deliver its energy as fast as possible, but lasers are pretty good that way.
Or just use a nuke-pumped x-ray laser.
Socialism: a lie told by totalitarians and believed by fools.
psychics and alien space-gods, and messiahs coming back from the dead
Did you miss the memo about sufficiently advanced technology? I believe it was sent by Mr. Clarke in the Long Term Projects department.
Virginia is for lovers. EVE is for griefers.
wrap the thing in polystyrene and depleted uranium rods boom hypersonic kinetic energy penetrators, fuck yo armour
Wouldn't it tend to vaporize anything nearby, and melt things that are a little farther away, but still within like a mile or two?
Well, let's think about this using the power of the maths! Let's assume a 300 kT TNT =~ 1300 TJ yield bomb (most common in our arsenal today, and bigger thermonuclear devices are probably impractical to carry into space), detonating at 1km from the target. Let's assume a normal warhead with a spherical energy dispersion pattern, and that's an energy density of 103 MJ/m^2 at the target.
The specific heat of aluminum is 897 J/(Kg*K) according to WP, though it would change with temp I'll use that figure as a constant. The mass of 1 m^2 of aluminum hull is 27kg/cm of thickness. Assuming all the energy is absorbed as heat and that it also magically heats the hull evenly through that's 4256 K*cm. Aluminum melts at 993K. So, whatever the starting temperature of the hull, you'd need at least about 5cm thick armor to prevent it from melting all the way through.
Now I actually have no idea how thick hulls are, but that seems pretty hefty.
The enemies of Democracy are
Those gamma and X-rays are bad news when absorbed by stuff like a spacecraft hull. The photon flux is so high that even transparent substances like air absorb ghastly amounts of those. That's the source of the atmospheric shock from a nuke, and the source of the distinctive thermal double-flash: initial infrared pulse, occluded after a few nanoseconds by the atmosphere flashing into opaque plasma, and the resuming after the shockwave begins to dissipate the opacity. Any substance more opaque than air will just immediately flash to plasma and create its own shockwave in the rest of the target.
Yes, the inverse-square law applies to the photon burst from a nuke in space, so a nuke is not the large-area weapon it is in atmosphere. But to write off the huge pulse of ionizing radiation is mistaken. A contact or near-contact nuke would hurt bad.
A perfect x-ray laser would be immune to the inverse-square law, but a perfect laser doesn't exist. Every real-world laser will have a divergence angle; that would give the beam with an inverse-square behavior with a constant coefficient based on the ratio of the divergence angle as a solid angle and the solid angle of a unit sphere (4 pi).
Welcome to the Panopticon. Used to be a prison, now it's your home.
I read the article - despite many correctly spelled words, it is absolutely devoid of strategic or tactical thought and shows evidence that the author has no combat planning experience - and I'll go out on a limb and say that there are so many artificial constraints that I very sincerely he ever read - or understood if he did - the Art of War.
You're a Mars Colonist. You revolt. OK - you're _expecting_ an attack. You won't wait for anything orbital from Earth - you'll pre-position killer drones - a mine field if you will - beginning at the LaGrange point between Earth and Mars and in layers anticipating the attacking fleet. Somewhere within the field - or to its edges - you'll arrange tracker-transmitters that will generate fake attack messages seemingly from Earth friendlies in an effort to steer the attackers into the mine field.
You're an Earth administrator and you're not idiot - your agents on Mars tells you that not only is the violent revolt coming, deep space assets are being prepared to thwart your approach.
You're a Mars propagandist - you shape public messages in order to inflame Earth, but one of your messages is seeming fuck-up, and you accidentally give away a secret regarding your strategic forces - but it's a plant to entrap Earth forces at a point besides the (kinda) mid-flight-point minefield - you're actually planning to outflank Earth.
You're a Mars agent - you seize an Earth civilian spaceliner and announce terrorist demands. You're not Earth, so you're not evil, it's a complete distraction, so your partner agents already on Earth can try to mess up launch logistics for Earth forces while paying attention to the wrong crisis.
And after a mile of more text like this - you can have all the space opera that the author wanted.
Space is simply not Earth.
TFA reads to me like Mars is supposed be some kind of Fort Apache - and I don't buy it.
Pathological kinda promises Path + Logical - but instead, you get stuck with pathetic.
Actually, nuclear weapons are likely to be far more lethal at great distance in space than in the atmosphere. The atmosphere absorbs most of the radiation from a nuclear weapon. The vacuum of space doesn't. It continues on and on, at dangerous levels for hundreds or even thousands of miles.
A ~50 megaton blast releases ~1e18 joules of energy. At 1000 miles, that's spread over 12.6 million square miles, or about 30 joules per square meter. 1 rad is 0.01 joules per kilogram, so a 100kg mass taking up 0.5 square meters would receive 15 rads. If we assume a Q factor of 5 for a nuclear weapon, that's 75 rem. That's enough to cause radiation sickness. Cut the distance in half (500 miles) and that's 300 rem -- the LD50 for humans.
The danger radius for nuclear weapons in space is *big*. Even if you add in enough shielding to reduce radiation exposure by 95%, and drop the nuclear weapon yield tenfold to 5 MT, you'd still kill over half the crew of the spacecraft from a dozen miles away. You don't really need to be even close. And radiation poisoning is not a nice way to go.
Nobody pushes buttons like our bunny. Big red buttons with labels that say "IGNITION", apparently.
As far as I know Independence War series (1 & 2) are the only PC games that implemented 100% true Newtonian physics. They took care of movement, heat issues, detection by heat and visual, whole shebang.
Who logs in to gdm? Not I, said the duck.
I have a few notes on space combat, lasers, railguns, stealth, tactics, delta v, nuclear shaped charges, ship design, and whatnot on my website. I am not a Ph.D, but many of the people who contributed are.
Atomic Rockets (index)
Space War: Introduction
Space War: Detection
Space War: Weapons Intro
Space War: Weapons: Conventional
Space War: Weapons: Exotic
Space War: Defenses
Space War: Warship Design
Space War: Strategy and Tactics