Kinetic impactors and other space weapons

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Fnord43
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Kinetic impactors and other space weapons

Post by Fnord43 »

Since it has been made clear that both of the major players view this as a war of survival/extermination, why not use relativistic bombardment.

Get a large rock, coat it in a very low reflection material, give it a basic guidance system and a long term propulsion drive to continually accelerate it so it gets to relativistic velocities.

Then jump into the star system neighboring the target, aim it at the target and turn on the drive then jump out. Then all you have to do is not lose for a decade and the enemy planets will be destroyed.

If you use one or two rocks for every major enemy population and manufacturing center you could destroy the vast majority of them. And it would be a lot cheaper in terms of energy and resources. This sort of attack would be nearly impossible to stop after the earliest stages, once it is going fast enough, no conventional attack could catch it, nothing could get to it in deep space, and once it arrives in the target system it would have enough mass and energy to plow through nearly any defense.

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Arioch
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Re: Kinetic impactors and other space weapons

Post by Arioch »

Fnord43 wrote:Get a large rock, coat it in a very low reflection material, give it a basic guidance system and a long term propulsion drive to continually accelerate it so it gets to relativistic velocities.

Then jump into the star system neighboring the target, aim it at the target and turn on the drive then jump out. Then all you have to do is not lose for a decade and the enemy planets will be destroyed.
Assuming for a moment that you can reliably hit an orbiting planet with a relativistic projectile from ~10 light years away (which is not a given), there are two problems that come to mind.

The first is that, in this case, there are no major production or population centers adjacent to a system you can reach. Any such settlements were largely destroyed or evacuated a long time ago by more conventional attacks (or the threat thereof). The industrial heartlands of both sides are far from the front lines.

The second is that, even if there were such targets, you'd have to plan to not win the war for another decade. Any territorial advances would result in your relativistic impactor attacking your own system, so you will have to actively forbid your military forces from going on the offense, and resign your population to at least 10 more years of casualties and war privations. Such a plan would be very tough on morale that may already be near the breaking point after such a long war.

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Diodri
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Re: Kinetic impactors and other space weapons

Post by Diodri »

Isaac Arthur on YouTube talks a lot about relativistic missiles on his channel, and stealth even for a solid chunk of metal with no propulsion is not completely stealthy. The reason he gives, is that because space is still filled with trillions of hydrogen atoms, your kill missile traveling at 10% the speed of light is slamming into quadrillions of atoms a second, which gives of many kilowatts of radiation, which is easily detectable by anything that can pick up radio waves.

Here's a link if you're interested, though he does also poke many holes into other aspects of space warfare, which kinda puts a damper on our notion of cool battles in space. You just have to roll with whatever in universe rules that are in place, because once you try to go too scientific the whole concept kinda breaks down.

https://www.youtube.com/watch?v=xvs_f5MwT04

entity2636
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Re: Kinetic impactors and other space weapons

Post by entity2636 »

Fnord43 wrote:Get a large rock, coat it in a very low reflection material, give it a basic guidance system and a long term propulsion drive to continually accelerate it so it gets to relativistic velocities.

Then jump into the star system neighboring the target, aim it at the target and turn on the drive then jump out. Then all you have to do is not lose for a decade and the enemy planets will be destroyed.
Starship Troopers movie anyone - the bug-launched asteroid that destroyed Buenos Aires?

I second Arioch in that such "weapons" are a) pretty absurd to begin with, b) impractical due to the time it will take for something to happen and c) one would deny one self any usable territory gained by conventional means.

Guided asteroids as weapons could make sense for asymmetrical intra-system warfare at a low tech level (our current one or 10-20 years in the future) where one side could choose to launch asteroids already present in said system as terrorist attacks at enemy installations or planets which they are unable to attack directly.

Note that in the Outsiderverse all nations present (even the Terrans) have very powerful conventional weapons - thermonuclear, fusion and antimatter explosives, and every starship of frigate size and above has enough of them to if not completely glass a planet, than at least destroy every large installation. If the only goal of the enemy is to damage infrastructure and terrorize the general public, then even with loroi's farseeing ability in place it will still be quite easy for a single fast ship or small squadron of fast ships to penetrate deep into enemy territory and kamikaze into their target. You know - space is big and it would be quite easy to avoid enemy patrols and boarder guards or outrun them if your ship is designed for such a task.

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Arioch
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Re: Kinetic impactors and other space weapons

Post by Arioch »

entity2636 wrote:Starship Troopers movie anyone - the bug-launched asteroid that destroyed Buenos Aires?
I vaguely recall that this attack also happened in the book version, though I don't think Heinlein went into any detail about it (wisely). The movie version is quite specific, saying that it came all the way from Klendathu (essentially the enemy capital), and making it clear through the encounter with the Rodger Young that it was not moving at any kind of relativistic velocity, nor did it have any visible guidance. Which of course makes the whole thing absurd; it would have to have been launched thousands of years prior. But ignoring the time scales of slower-than-light travel is unfortunately a hallmark of movie and TV scifi (most notably Star Wars and Star Trek; in each milieu, the heroes' ship at some point travels from one system to another on sublight drives in a matter of days or weeks).
entity2636 wrote:Guided asteroids as weapons could make sense for asymmetrical intra-system warfare at a low tech level (our current one or 10-20 years in the future) where one side could choose to launch asteroids already present in said system as terrorist attacks at enemy installations or planets which they are unable to attack directly.
A good literary example is from The Mote in God's Eye: one the first clues that the Moties were fratricidal maniacs was that the Lagrange points near their planet were absolutely picked clean of asteroids.

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Re: Kinetic impactors and other space weapons

Post by Krulle »

Kinetic impactors may be a choice in a universe where Einstein is still right: limited speed for matter.

When the army travels slower than such a kinetic impactor would, such weapons also make good counter-threads:
if your planet gets destroyed, your impactor, parked outside the Oort cloud, starts accelerating toward the target which attacked your homeworld.

Making any victory a phyrric voctory.
Kind of like our nuclear weapons were during the cold war.

But in a faster-than-light travel section?
They become difficult to handle effectively, when your fleet has simply more tactical abilities.
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Harusame
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Re: Kinetic impactors and other space weapons

Post by Harusame »

The Lost Fleet is a military science fiction series written by John G. Hemry Showing good examples of.
Space combat with low relativistic Speeds and the use of dumb kinetic bombs aka "Rocks".

In a sytem aiming and hitting something that does not Change Delta V is kind of easy.
You don´t Need relativistic speeds just along very dense, heat resistent needle...hard to spot, If you hit it congrats.
You just turned a slug in a bugshot.

But as Arioch said no Target there ^^.

But in case of a System Invasion with planetary Targets I would
First fire some "Rocks" at targets of opportunity, Stations ect. just to get my opposing force to react.
These "Rocks" don´t Need to be planet sluggers just enough bang to destroy roads, orbital, sattelites ect.
They can use slingshots to be less predictable and even to do delayed attacks if I´don´t intend to stay.

"I hope my auto correction did not mess up the text to much ^^° I´miss my old OS"

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SVlad
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Re: Kinetic impactors and other space weapons

Post by SVlad »

By the way there already was a discussion about kinetic weapons.
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SVlad
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Re: Kinetic impactors and other space weapons

Post by SVlad »

Starship Troopers - either the scenarist was a moron, or humans throw that asteroid themselves in a false flag operation (conspiracy!).
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Arioch
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Re: Kinetic impactors and other space weapons

Post by Arioch »

Krulle wrote:When the army travels slower than such a kinetic impactor would, such weapons also make good counter-threads:
if your planet gets destroyed, your impactor, parked outside the Oort cloud, starts accelerating toward the target which attacked your homeworld.

Making any victory a phyrric voctory.
Kind of like our nuclear weapons were during the cold war.
Such a weapon surviving is dependent on it remaining secret. Secret weapons have no deterrence value. I think a civilization would be better served to spend its resources on weapons or systems that will help prevent it from being destroyed in the first place.

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Re: Kinetic impactors and other space weapons

Post by Krulle »

Well, nuclear weapons did a terrific job in that.
Just look at the Kim dynasty.
The weapon they have access too guarantees their survival.

There is no need to keep,it,secret itself, just keep the exact parking position a secret, and the actual speed it will travel.
Nobody will know when the impactor actually arrives.
And if accelerated enough, the radiative scattering it causes will not arrive much earlier than the impactor itself.


Anyway, for the outsider setting they are irrelevant.
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Luge
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Re: Kinetic impactors and other space weapons

Post by Luge »

This is a pretty old argument in science-fiction discussion land. I present to you an article was originally taken from the internet by Jervis Johnson (of Games Workshop fame) and published in White Dwarf 227 by Andy Chambers. The original author is Patrick Marstall.
Rocks are NOT ‘free’, citizen.

Firstly, you must manoeuvre the Emperor’s naval vessel within the asteroid belt, almost assuredly sustaining damage to the Emperor’s ship’s paint from micrometeoroids, while expending the Emperor’s fuel.

Then the Tech Priests must inspect the rock in question to ascertain its worthiness to do the Emperor’s bidding. Should it pass muster, the Emperor’s Servitors must use the Emperor’s auto-scrapers and melta-cutters to prepare the potential ordinance for movement. Finally, the Tech Priests finished, the Emperor’s officers may begin manoeuvring the Emperor’s warship to abut the asteroid at the prepared face (expending yet more of the Emperor’s fuel), and then begin boosting the stone towards the offensive planet.

After a few days of expending a prodigious amount of the Emperor’s fuel to accelerate the asteroid into an orbit more fitting to the Emperor’s desires, the Emperor’s ship may then return to the planet via superluminous warp travel and await the arrival of the stone, still many weeks (or months) away.

After twiddling away the Emperor’s time and eating the Emperor’s food in the wasteful pursuit of making sure that the Emperor’s enemies do not launch a deflection mission, they may finally watch the ordinance impact the planet (assuming that the Emperor’s ship does not need to attempt any last-minute course correction upon the rock, using yet more of the Emperor’s fuel).

Given a typical (class Bravo-CVII) system, we have the following:

Two months, O&M, Titan class warship: 4.2 Million Imperials
Two months, rations, crew of same: 0.2 MI
Two months, Tech Priest pastor: 1.7 MI
Two months, Servitor parish: 0.3 MI
Paint, Titan class warship: 2.5 MI
Dihydrogen peroxide fuel: 0.9 MI

Total: 9.8 MI


Contrasted with the following:

5 warheads, magna-melta: 2.5 MI
One day, O&M, Titan class warship: 0.3 MI
One day, rations, crew of same: 0.0 MI
Dihydrogen peroxide fuel: 0.1 MI

Total: 2.9 MI

Given the same result with under one third of the cost, the Emperor will have saved a massive amount of His most sacred money and almost a full month of time, during which His warship may be bombarding an entirely different planet.

The Emperor, through this – His Office of Imperial Outlays – hereby orders you to attend one (1) week of therapeutic accountancy training/penance. Please report to Areicon IV, Imperial City, Administratum Building CXXI, Room 1456, where you are to sit in the BLUE chair.

For the Emperor,

Bursarius Tenathis,
Purser Level XI,
Imperial Office of Outlays.
L.

Harusame
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Re: Kinetic impactors and other space weapons

Post by Harusame »

OH I remember that one I have the issue still in my basemments archive.....^^° God dear, If I ever move again

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icekatze
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Re: Kinetic impactors and other space weapons

Post by icekatze »

hi hi

I don't think Warhammer 40k counts as being even a little bit in the realm of hard science fiction. :lol:

entity2636
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Re: Kinetic impactors and other space weapons

Post by entity2636 »

Indeed it doesn't, but the example provided still works to illustrate the impracticality of using asteroids as projectiles :)

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Re: Kinetic impactors and other space weapons

Post by dragoongfa »

Diverting an asteroid is indeed an expensive and probably ineffective alternative at the techlevels involved. Railguns designed for orbital bombardment would destroy any target without negatively impacting a planet's environment. A weapon that fires a solid metal slug projectile with a diameter of a few meters at a speed of 100 kilometers per second would really mess up everything it hit.

Just play with this basic calculator a bit and input some plausible numbers for a proper bombardment railgun slug:

http://convertalot.com/asteroid_impact_calculator.html

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Re: Kinetic impactors and other space weapons

Post by Luge »

entity2636 wrote:Indeed it doesn't, but the example provided still works to illustrate the impracticality of using asteroids as projectiles :)
This guy gets it.

L.

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Re: Kinetic impactors and other space weapons

Post by icekatze »

hi hi
entity2636 wrote:Indeed it doesn't, but the example provided still works to illustrate the impracticality of using asteroids as projectiles :)
It provides an example, but not a remotely realistic one.

Firstly, you send a small craft up to the asteroid, sustaining no more damage to the paint from micrometeoroids than they would under normal operations.

Then the asteroid, having been inspected by radar, lidar, and spectroscopic analysis well in advance as a suitable object, is seeded with a mass driver and a small drilling robot. The robot then proceeds to melt down parts of the asteroid to use as fuel for the mass driver, which propels the asteroid into a different orbit.

The offending planet, which apparently does not having a space navy capable of confronting you as you maneuver around in their own system, is consequently unable to mount an asteroid diverting mission in time.

The end.

Depending on the tech level, throwing rocks may be effective or ineffective, but it's not going to be particularly expensive.

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Re: Kinetic impactors and other space weapons

Post by Gorbash »

icekatze wrote: Depending on the tech level, throwing rocks may be effective or ineffective, but it's not going to be particularly expensive.
By your statement, the expense of moving the asteroid in question is going to depend heavily on the robot, the driving engine, and your time-table.

Most asteroids don't have a lot of hydrogen and oxygen. Comets do, but kind of as a result, they tend to be pretty low mass; you'll have to hit a much higher % of C (eating up more of your comet) in order to do damage to your expected target. As such if you're not using hydrogen and oxygen as your easy fuel source (and that depends heavily on your tech level and the nature of the asteroid, but unless its chock-full of uranium and you're using nuclear power to toss those chunks of rock you're propelling it with, you'll need something that doesn't rely on light-element fusion), you'll probably want to import fuel. "Melting random bits of asteroid" doesn't work unless you've specifically found an asteroid that's mostly a reactive fuel source.

And keep in mind, this is a "lot" of power. Even in a vacuum it takes a significant amount of energy to distort the orbit of a kilometer-large hunk of stone, particularly if you're planning on hitting a (predictably) moving target at high speed. If you're relying on the contents of your asteroid as fuel, you're going to use up a lot of asteroid just pushing against the asteroid's inertia (and probably the momentum of its standard orbit).

I'm going to agree with the old 40k meme here. Rocks ain't free.

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Re: Kinetic impactors and other space weapons

Post by entity2636 »

Rocks ain't free, time costs money and war time costs lives. One would be spending a considerable amount of time, materiel and effort picking out a suitable asteroid, installing the necessary propulsion and guidance systems on it and waiting for results. If the opposing faction doesn't have means to counter the asteroid impactor, or hinder you rolling around in their star system for days to weeks or more, it also begs the question as to why all this effort, unless one is simply being evil for evil's sake, throwing rocks at a planet that can't defend themselves against them. Then one could just as well simply fly over and drop some nukes from orbit.

On second thought, this gives me an idea for a bit of a dick move maneuver that could be pulled off even in Outsiderverse. You could take a small fast ship, a courier or scout corvette and have it carry a couple of capital ship size antimatter torpedoes on external mounts. You jump into an enemy system, accelerate on a course toward your target, release the torpedoes without firing their engines practically from the edge of the star system, then turn away and jump out. Space is big so it's highly unlikely that you'll be caught and the torps you released will travel on inertia towards their target without emitting an engine signature and could go completely unnoticed or being mistaken for space junk until too late.

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