"Realistic" Space Combat/Travel Discussion Thread

[Sponge]

I was really liking the direction the old thread was taking for a while there, but it broke down fairly quickly into numerous incompatible topics due to there being no overarching theme. I urge any interested parties to continue the discussion here. But first, a few important assumptions.

The List of Important Assumptions (please read before posting)

• Time frame: realistic near future.
  Space combat and travel using today's technology is not feasible. Our hulls would be so thin that an errant chunk of rock would make for a very bad day. We also lack the ability to build in space efficiently, which is almost required due to the difficulty of getting incredibly massive objects into orbit. Far future is simply too hard to predict. At this point, there could be things we regard as impossible that would be mainstream with the requisite technology.
• No Faster Than Light (FTL) travel.
  FTL travel is not realistic in the near future. Barring some groundbreaking discovery, attaining FTL velocities will remain well out of humanity's reach for quite some time.
• Keep energy requirements sane.
  Keep in mind that all power must be generated on a space ship, where space is limited and mass needs to be as low as possible to facilitate movement. Such feats as accelerating masses to significant fractions of c are not plausible under these circumstances.
• Ships are incapable of leaving a given system within a reasonable time frame.
  This really only concerns combat. From an exploration perspective, time is not necessarily of the essence.
• General discussion will involve large ships.
  Probably several hundred meters or more. If you want to talk fighters or smaller vessels, feel free. Just make sure you mention what size ship you're talking about. Also remember to keep your size vs. armament consistent. 100m carriers are implausible, as are 100m fighters.
• I'll add to this list as new things come up.
  Feel free to suggest things, if you feel inclined to do so.

[Slayer0019]

If we're talking near future, weapons and armor would be... interesting. Near future means cannons, whose recoil would knock a ship significantly without countering thrusters, and then fuel might be limited.
Also consider that objects in orbit move really fast, so even hitting the target would require either sophisticated tracking computers (or maybe not so sophisticated, I know nothing of coding) or really good gunners.

If we include Navy prototype railguns and lasers as seen on experimental anti-missile aircraft, hitting might be easier, but energy consumption becomes a problem. Nuclear reactors as seen on Naval vessels could work, though a meltdown in space would likely result in complete destruction of the craft, though it would undoubtedly look really cool.

Armor would probably need to be either very thick or very advanced, beyond that I don't know.

Space combat however does not seem likely (at least within my lifetime) due to technological constraints, danger to crew, and obscene manufacturing and operating costs.

[Siber]

Would you care to explain any of those points? Why does near future mean cannons? Why do cannons necessarily mean that the recoil enough would be enough to be a major maneuvering concearn? We have the ability to put sats where we want, to shoot down sats that are in orbit, to rondevous space craft... I doubt that hitting another ship is going to be a real problem, assuming it's not dodging.

Why, exactly, would a meltdown in space be particularly dangerous? Why would a meltdown be a risk that needs much consideration at all?

More generally, any reason this shouldn't be in Ect instead of BSF discussion?

[Hypothetical Wisdom]

This is in BSF general discussion because it's the sequel of a thread that was also in BSF gen disc: "You sunk my..."

[Siber]

That thread had multiple references to BSF and how it relates to realism. This one doesn't. Thanks for helping me make up my mind.

[Sponge]

Near future means cannons

Railguns seem a far more attractive alternative, largely because you can get them going really, really fast. Chemically powered weapons might work for things like flak, but otherwise they won't be able to close the distance quick enough.

whose recoil would knock a ship significantly without countering thrusters, and then fuel might be limited.

It takes an awful lot of force to move an object as massive as a several hundred meter long chunk of armor. Yeah, there'd be some recoil, but I don't see it accomplishing much more than slowly inching you away from your target. Realistically, ships would have to be able to vector the thrust from their engines in virtually any direction in order to compensate for things like recoil, enemy attacks, or just to change direction.

Also consider that objects in orbit move really fast, so even hitting the target would require either sophisticated tracking computers (or maybe not so sophisticated, I know nothing of coding)

Fighting in orbit wouldn't be terribly viable, simply because all you need to do is get to the far side of the planet to avoid any and all fire. Granted, you'd have someone chasing you, you'd have a head start. As ships would likely be built in orbit, any attacker would have the disadvantage of having to travel to the target, which would know for quite some time that an attack was coming. Targeting isn't likely to be a problem at such close ranges. Changing direction completely requires not only accelerating in that new direction, but also completely decelerating in the old one. In other words, it'll take a while. Compensating should be easy.

If we include Navy prototype railguns

I don't doubt that in the "realistic near future," they won't be prototypes anymore. We'll likely have much more powerful variants.

and lasers as seen on experimental anti-missile aircraft

Again, we won't be talking prototypes. We'll be talking a few hundred MJ, which would do some serious damage. It's also the fastest moving weapon possible. Even so, lasers do have an effective range.

Nuclear reactors as seen on Naval vessels could work, though a meltdown in space would likely result in complete destruction of the craft, though it would undoubtedly look really cool.

Fusion would probably be the way to go. Not only is it more efficient than fission, but it's also a lot safer. Meltdowns don't seem likely, but in any case, it seems like some sort of containment systems would be implemented, even if it involved somehow ejecting the reactor.

Armor would probably need to be either very thick or very advanced, beyond that I don't know.

Yeah, I don't know much about armor either. Thickness would be nice, but keep in mind-- the heavier you are, the longer it takes to maneuver. Something that takes a lot of energy to burn through would be good. Maybe something carbon based. Boron might be even better. One thing to keep in mind is that something that protects from lasers may not be great at keeping back kinetic (railguns) or explosive (rockets) weapons. One final consideration is that to get through an armor plate, you have to either hit it hard enough to break it in one shot (not likely; it's not good armor if you can do that) or hit the same segment repeatedly, which would be pretty tough.

More generally, any reason this shouldn't be in Ect instead of BSF discussion?

None at all, actually. I was reading the other thread as a reference while writing this one, and forgot to switch forums. Totally slipped my mind. Sorry about that.

[Siber]

All the well thought out hard sci-fi treatments I've seen(by people much more familiar with the math than me, so I can't really do the numbers for you) boil down to combat being a game of dodging entirely, with the only armor being radiation shielding.

[Krynvelhat]

Would be pointless combat.

Railguns would rip apart anything not completely coated in ultra-heavy armor. Cannot intercept a railgun. No such things as shields, and point defense would only be effective against missiles and torpedoes.

[Squishy]

All the well thought out hard sci-fi treatments I've seen boil down to combat being a game of dodging entirely, with the only armor being radiation shielding.

You mean something like space jousting?

[Siber]

Somewhat, Squishy. You dodge a lot and hope it's enough, use point defense if possible, and mostly just hope your shots hit the enemy before their shots hit you.

Why, exactly, can't you intercept a railgun?

[Krynvelhat]

A railgun projectile would be moving towards the target at a massive velocity - it would be difficult to move an object into position to intercept the projectile.

[Siber]

It's also difficult to hit an intercontinental ballistic missile in mid flight with another missile. But we're getting closer to doing it reliably all the time. Difficult isn't impossible, and you only need to deflect the projectile enough to make it miss you, you don't have to kill it. Shoot it with your own, smaller, fast tracking railguns, perhaps.

[Sponge]

Given the technology required to put a massive ship in space (which I know goes against your line of reasoning, Siber. I believe both schools of thought have their relative merits), point defense/flak should be advanced enough to make a pretty nasty cloud that would at least knock most rails off course. Also keep in mind that railguns are relatively slow. Even assuming mach 20, well beyond our current capability, they'd be slower than both missiles, which potentially have the ability to accelerate for long periods of time, and lasers.

I'd like to run some numbers on the kind of impact some more advanced armor candidates could take. I'm looking into some of the harder boron-based compounds, as well as beta carbon nitride. I don't remember off the top of my head how to work these calculations (and this is further compounded by the fact that the specs on these materials are few and far between), so I may or may not get around to it. I suspect, though, that materials ~50 years from now shouldn't have too much trouble with railguns.

[TrashMan]

For all your Sci-fi reality questions...look no further:
http://www.projectrho.com/rocket/

[Normandy]

I'm interested in space-to-ground tactics. Assuming we establish a base on say, Mars or the Moon, what tactics could be employed to assault it if necessary?

Orbital bombardment? Fire from the skies? If bunkers are built deep into Martian or lunar soil [in lack or a better word], they could survive quite a beating, and serve purposes outside of sheer military protection (e.g. radiation shielding).

Or what if you needed the habitat intact, or at least mostly intact, and you needed to send in a strike team. How exactly is that carried out?