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."

Comments

round round, I git around

[Tablizer]

Sounds like the ideal shape for spaceships will be spherical

That'll be boring: round ships, round planets, round explosions, and round movie goers.
   

Re:round round, I git around

[c6gunner]

The problem is that reducing the profile in one direction means you have to make it larger in a different dimension. Now, that's not much of a problem when you're fighting 2D land-battles, but zero-gravity gives you the ultimate 3D battle-space. If your enemy is smart enough to put one fleet directly in front of you while having another flank from the top or bottom, all you've done is make your ships easier to hit.

If you're looking at it purely from the perspective of presenting the smallest profile possible, your best bet would be a needle-shape. Very long, and as thin as possible. However, that runs into other problems, such as maneuverability.

Re:round round, I git around

[Anonymous Coward]

You'd actually need to attack from 3 very different directions for a saucer shape to be a liability. From any two directions, you can orient your ship so both attackers are on the plane of your lowest profile.

Plus, large surface area in one direction confers a key advantage- more space to mount weapons. A saucer-shaped ship would have the flexibility of being able to offer both a broadside of heavy fire or a small target to any given enemy position.

Re:round round, I git around

[Rei]

It depends on what axis of maneuverability you're talking about. A vehicle will have a low moment of inertia around its narrow axes but poor about its long axes. Of course, that's why the flak concept is so important -- to make it harder to miss. One concept that the US military threw around for a bit was launching what basically amounted to a missile full of sand/grit into orbit, esp. one counter to the Earth's rotation. You want to ensure damage -- how about being nailed by hundreds of chunks of rock moving at a relative velocity of over 15,000 meters per second? It'd render LEO inaccessible for years.

As for your comments about making yourself more exposed in one axis while decreasing it in others, I think the author actually addressed that point well. Until we have tech that allows for virtually unlimited thrust at virtually no cost, there *will* be orientation implicit in space. You don't just go whatever direction you want in a gravity well, you still need to factor in launch windows, etc.

On that front, I'm reminded of an old game I used to play, called VGA Planets. A very fun multiplayer game, although everyone's empires tended to become too unwieldy to manage after many turns, and players would start to drop out until there was nobody left. In the game, you built various starships (freighters, warships, crew transports, etc) and dispatched them to various star systems to colonize their planets. Your planets and starbases had long-range radar and could detect incoming ships (some being stealthier than others) -- the closer it came, the more data you could get about it. By paying attention to the ship's trajectory and velocity, you could forecast where it was likely to be in future turns, and dispatch warships for an intercept and capture. A clever countermeasure, therefore, was to not always take the optimal route between planets, but to slightly offset your angle and velocity each turn so that if someone tries to set up an ambush, you sail past it. As a counter to the countermeasure, some players would send multiple warships and spread them out along the route, since capturing an unescorted Large Deep-Space Freighter didn't exactly require a powerful fleet. And I would have fun by setting the callsign for my most powerful warships, "Large Deep-Space Freighter", hoping that people who weren't paying enough attention to what they were seeing would mistake the callsign for the ship class (it actually worked several times).

Any way, the reality with space combat is much more boring. There's no way a Mars colony could become truly independent from Earth for many, many centuries. Try to trace back the resources needed to, say, run a CPU fab, or even a nuclear fuel cycle. Modern technology is produced from an unfathomably large web of interconnected part and resource dependencies that we have spread across the entire Earth. And future tech will be even more complicated to produce. So the reality is that if Mars wants to rebel, all Earth needs to do is cut off shipments to them and they'll slowly wither away as things break that they can't replace.

Not much surprising

[JoshuaZ]

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.

Re:Peace

[Xphile101361]

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

in the war of 1812

[circletimessquare]

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)
 

Heinlein

[Garrett Fox]

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.