[World Building] A Future History of Space Force

[Anthony]

The thing about missiles on space craft is... why not just cut out the middle man and send the missile directly?

[RyanW]

Originally Posted by Fred Brackin

Even missiles need to get to their target before lasers kill the launching vessel. At least the launching vessel hopes so.

If this is not possible only expendable drones will launch long range missiles (which will have to be autonomous).

If anything, intercepts in space are a simpler mathematics problem than in atmosphere, so I don't know why you wouldn't have missiles with fire-and-forget capability.

[Verjigorm]

Originally Posted by Fred Brackin

I know of no country using missiles on long range space vehicles.. We're not talking about the near term.

I'm talking about near-term, TL8 space combat.

[Verjigorm]

Originally Posted by Anthony

The thing about missiles on space craft is... why not just cut out the middle man and send the missile directly?

delta-v costs. There's a lower limit on size for better propulsion systems for deep space travel, as well as cost.

[Fred Brackin]

Originally Posted by Verjigorm

I'm talking about near-term, TL8 space combat.

Why? The OP wants warships for 2120+ and we're on the edge of TL9 with no sign of anyone building any space combatants.

[sir_pudding]

Originally Posted by Anthony

The thing about missiles on space craft is... why not just cut out the middle man and send the missile directly?

Decision loops? If I have command decision elements on Europa and you are stuck on Earth responding by chucking missiles, presumably my OODA loop is a lot shorter for events nearer to Jupiter than Johannesburg.

[thrash]

Originally Posted by PTTG

Oddly, this suggests that spacecraft the size of refrigerators or cars might be fighting each other with belt-fed guns on turret mounts.

Car Wars IN SPAAACE!

Originally Posted by Verjigorm

I don't know if any lasers that have been successfully used to kill space targets. I do know of several countries using missiles.

There is some speculation about laser ASAT capabilities but nothing confirmed in the open source literature. So far as I know, all of the ASAT tests with missiles (vs. just ramming one spacecraft into another) have been ground-based.

If you count Hayabusa I and II, there have been instances of firing projectiles from one space object to another.

[Varyon]

Originally Posted by PTTG

Oddly, this suggests that spacecraft the size of refrigerators or cars might be fighting each other with belt-fed guns on turret mounts.

As much as Space Car Wars sounds awesome, do keep in mind that automatic chemical-propellant weapons also have issues with heat buildup. Perhaps not as much as modern lasers have (particularly if you assume these Full Auto Fridges are using polymer-cased munitions), but it certainly isn't a negligible amount, particularly when you don't have a convenient atmosphere to dump all that waste heat into.

EDIT: On the other hand, spin stabilization doesn't seem like it would be necessary without an atmosphere to tumble through, and I think smoothbore barrels may not heat up quite as quickly as rifled barrels (the latter needs friction to impart the spin), so maybe it would be less of an issue?

[RyanW]

Originally Posted by thrash

There is some speculation about laser ASAT capabilities but nothing confirmed in the open source literature. So far as I know, all of the ASAT tests with missiles (vs. just ramming one spacecraft into another) have been ground-based.

Well, there was the air-launched ASM-135. The deploying aircraft was ground-based, of course.

[Anthony]

The core issue with solving problems in space with unguided bullets is that there's a range at which the mass budget required to dodge the bullets is smaller than the mass budget of the bullet, and that distance isn't that far.

Let's say you're shooting at a 1 ton target at a range of 100 km, and you expect to need 100g of ammunition (with a muzzle velocity of 1 km/s) to deliver a killing blow. For the target to dodge, it needs to move by at least 1 cm/sec for the 100s between you shooting and your bullets arriving -- total delta-V of 10 kg*m/s. Typical chemical propellants have an exhaust velocity of 2-4 km/s, at 2 km/s that 10 kg*m/s costs you... 5g of propellant.