Decoys in space warfare (hard sci-fi)

[Dilandu]

The general rule of hard sci-fi is that there is no (easy) stealth in space, and I'm perfectly content with it. What I have some troubles with, is that this rule include decoys, too. I like decoys) So I brainstormed quite a long time, and came with the idea of drive system, that - theoretically - could allow massive ship and light decoy to be pushed on different trajectories without enemy being able to discriminate - which one is which.

* Both the ship and the decoy are equipped with "indistinguishable maneuvering" chemical thrusters, specifically designed to alter their trajectories in such way, that enemy observer would not be able to discriminate - which one is which;

* The thrusters are of external pulse reflection type - essentially "Orion"-type pulse drive, but with chemical shaped charges instead of nuclear. They are dropped behind the ship/decoy and exploded, pushing the ship/decoy through the pusher plate with shock absorbers;

* The pulse charges for both Type A (on the ship) and Type B (on the decoy) thrusters are exactly the same, and their pulses are completely similar;

* What is different is the interation between the charge and the ship/decoy - i.e. how much energy from each pulse charge is used;

- the Type A thruster (on the ship) have pusher plate of highly efficient, concave profile, specifically designed to utilize as much energy from pulse charge as possible;

- the Type B thruster (on the decoy) have highly inefficient pusher plate - narrow cone, latticework, specifically designed to utilize as little energy from pulse charge as possible;

* So the whole idea is, that observable velocity change for both ship and decoy would be the same from each pulse;

To illustrate it better, the 1000-ton ship utilize 100% of each pulse power (the numbers are purely for demonstration), and the 10-ton decoy utilize only 1% of each pulse power. Mass difference - 100:1. Thrust difference - 100:1. Velocity change - 1:1.

Of course, there would be differences in thermal load on plate (the amount of heat absorbed with each pulse), but we could circumvent them by using ablative coating of different thickness, different plate materials (with different heat conductivity), ect. And to further confuse the enemy sensors, we could add chaffs and flares to each pulse charge, released just before charge detonation - so the enemy fine-tuned telescopes and radars would be already half-blinded by sudden bright flashes by the time actual charge would work. And would not be able to detect the fine differences in gas clouds, before they would dissipate too much.

So that's my idea for hard sci-fi space warfare decoys. Would be glad to hear any criticism of the concept (alas, I'm not a specialist in rocket propulsion)

 

[Seragina]

OK, I'm game. Writing from the top of my head here.
Asuming today's & near future (<50a) (sensor) technology; assuming there are no additional traces from the ships in play; assuming Einsteinian mechanics and ship navigation still under the tyrany of gravity & rocket science; assuming no other super technology.

I assume your key rule is the explosion signature can be seen, hence, serve as the means in this warfare.
We can detect it in all available spectrum on hand so "blindness" is relative. Blindness in astronomy is about something outshining others. It's unlikely a flare could ever outshine the charge's explosion.
We see and known the point of the explosion, its distance, and triangulate to a certain degree. We see its "halo", the expanding shockwave material layer. It might be possible to see the shadow within the expanding gas left behind by the ship's body. This gives a rough vector.
Using hyperspectral sensor it should be possible to detect traces or the differences in the interstellar medium caused by RCS. It may not be possible pinpoint the original location but it should be possible to see their moment.
Using math, statistics etc. a lot could be determined from the data.
Realtime and time critical localization will be a challenge but not impossible. The problem is the error margin increases proportional with distance as well as the speed of the ship/decoy. So even if both ship and decoy locations are determined the volume they occupy could be millions of cubic kilometers in size. Only future energy weapons with high velocity could engage, uncover the real location and do damage.
If we assume the ship's hull doesn't absorp all possible electromagnetic spectrum then we could use quantum camera/laser comms to detect it depending on re-emission coefficiency and its size like 1 m per 2 lightsecond of distance.
So this will work as an annoyance but not 100% stealth proof. But probably sufficient for special circumstance surprise attack case depending on closure speed or velocity of released weapons.

 

[Dilandu]

I assume your key rule is the explosion signature can be seen, hence, serve as the means in this warfare.

Well, my general idea was to push real ship and decoy(s) on different trajectories in such way, that enemy would not be able to easily determine which one is real ship. Basically, I took inspiration from ICBM decoys, deployed to cover the real warheads; the enemy could see both, but can't easily discriminate between them.

So my concept is that ship burn to trajectorty, deploy the decoys, and then use external-pulse boosters (both for ship and decoys) to confuse enemy about real ship position and course. The enemy could see both the ship and decoys; but the enemy did not know which one is which.

(of course I assume that decoys are similar enough in external appearance to real ship)

 

[Michel Van]

Interesting concept
however a 1000 ton spaceship has allot momentum and need allot power for course correction.
it must turn in 3 axis then fire main engine to get in new trajectory
Chemical reaction system issue: you need fuel and with 1000 ton ship its Allot fuel
with the chemical explosive same problem

But what about high speed flywheels ?
no fuel and can rotate the Orion in 3 axis

on Decoys
What about ECM system that emulate it's Orion
with radar and Laser Target system aiming on enemy ship
if enemy approach from far distance and only one point in sensor
and it divide in several points who target them all at once.

 

[Dilandu]

however a 1000 ton spaceship has allot momentum and need allot power for course correction.

True, but again, the goal is to present enemy with several targets on different trajectoris - not much diffierent, of course, just enough to cause confusion.

What about ECM system that emulate it's Orion
with radar and Laser Target system aiming on enemy ship
if enemy approach from far distance and only one point in sensor
and it divide in several points who target them all at once.

Completely possible, yep.

 

[SleepyJerry]

I suspect there's a premise problem with this idea:
The post assumes a 1,000t ship and a 10t decoy, giving a 100:1 mass ratio and a 100:1 thrust ratio, so they'd have the same maneuverability.
But, the Orion drive is designed for nuclear warheads, whereas the post is using chemical shaped charges, which have a much lower propulsive ISP.
So if this decoy is going to carry the same number of charges as the ship, the total mass of those charges could end up being way more than 10 tons. And if you cut down on the charges to keep the total mass under control, then the decoy can only simulate fewer pulses — maybe just a few dozen, or even just a handful. The enemy only needs to watch for a bit longer before the decoy runs out of charges and loses its maneuverability, or its trajectory starts diverging from the ship's. That kind of decoy has way too short a "lifespan" to be tactically useful.

 

[Dilandu]

I suspect there's a premise problem with this idea:
The post assumes a 1,000t ship and a 10t decoy, giving a 100:1 mass ratio and a 100:1 thrust ratio, so they'd have the same maneuverability.
But, the Orion drive is designed for nuclear warheads, whereas the post is using chemical shaped charges, which have a much lower propulsive ISP.
So if this decoy is going to carry the same number of charges as the ship, the total mass of those charges could end up being way more than 10 tons. And if you cut down on the charges to keep the total mass under control, then the decoy can only simulate fewer pulses — maybe just a few dozen, or even just a handful. The enemy only needs to watch for a bit longer before the decoy runs out of charges and loses its maneuverability, or its trajectory starts diverging from the ship's. That kind of decoy has way too short a "lifespan" to be tactically useful.

True, that's why I intend it only as means to change trajectory a bit, making it's unpredictable. Basically the idea is like missile bus with individual re-entry vechicles.

 

[Justo Miranda]

Most of the military science fiction I've read deals with spaceship combat with the same parameters used in historical naval battles.

As far as I know, no author considers in depth the enormous difficulty represented by distances in space or three-dimensional combat, although they have a great deal of material on real air combat.

These authors imagine large Yamatos firing from a few kilometers using kinetic munitions to weaken the enemy's electromagnetic shields before firing TORPEDOES at them!!

At the same time, they freely use anti-gravity technologies for the inertia dampers and sensors so advanced that they can identify signs of life inside enemy ships through electromagnetic shields and metal hulls.

So, they can locate enemy ships at the other end of a solar system, approach them for days at a tenth of the speed of light, and only start firing when they are within range of optical sensors.

I like stories of space combat, but they were surpassed in Nelson's time by the advances of real science.

A little scientific training and common sense would be appreciated

 

[Seragina]

The key metric in real world space combat is time.
Acceleration, speed, distances all can be represented as a time value in time. The officers only needs to know time to align and time his decisions and actions.

We humans don't have a big enough brain nor mental fortitude to do all the calculations let alone accounting for relativity. Even day to day 3 dimensional (visual) judgment is impossible for most people let alone things purely running virtually in your head. Authors rely on their (life) experiences to write and there aren't alot of jobs with similar experiences (astronauts, fighter pilots, submariners).
Ofc authors could make statesments of time and all but they will fall apart as soon as someone analyses and recreates the battle.
It's too much to ask for today.

 

[SleepyJerry]

Also, a highly efficient concave pusher plate would direct the exhaust products into a tighter, more focused stream backward, whereas the decoy's grid pusher plate would let the products spread out. The two would differ in plume shape, expansion speed, and their signatures across spectrum, radar, and reflectivity. Even use flashbangs to temporarily blind optical sensors, radar and post-event observation could still track the expanding wake and tell which one is the more efficient.

 

[SleepyJerry]

Most of the military science fiction I've read deals with spaceship combat with the same parameters used in historical naval battles.

The problem is that a story needs more than scientific accuracy—it also has to be interesting, or readers simply won't buy into it.
A realistic space combat would probably look like some bizarre hybrid of BVR combat, artillery duels, and submarine warfare. It's hard to find a good analogy to capture such a strange form of indirect fighting.

As far as I know, no author considers in depth the enormous difficulty represented by distances in space or three-dimensional combat, although they have a great deal of material on real air combat

And even depicting a BVR engagement with real-world grounding is difficult enough, after all, intense dogfights are just more compelling.

 

[Scott Kenny]

A realistic space combat would probably look like [...] submarine warfare.

Submarine warfare is all about hiding.

Napoleonic naval might be closer. You can see where someone is for significant distance/time before the engagement starts. Days, even.

And even depicting a BVR engagement with real-world grounding is difficult enough, after all, intense dogfights are just more compelling.

They are.

 

[Justo Miranda]

Three years ago, I wrote a short story with my ideas of what asymmetrical space combat could be, criticism is allowed to improve it.



May 22, 2150

07.53 GH

- Pest control ship Silver Queen leaves hyperspace 10 Astronomical Units from the Ise-73 star to rendezvous with a Delian cargo ship.

09.32 GH

Delians are very secretive people who do not use artificial intelligence devices on board their ship, for ideological reasons. They do not speak the Universal language well and during the meeting I had to use the translator several times to understand the terms of the contract. They are willing to pay me 45,000 BT$ if I manage to kill a fairly large carnivore that causes trouble for humans on the Delion planet.



May 23

08.26 GH

The monster is dead. It has been such an easy job that I wonder why the Delians prefer to pay rather than kill it themselves. According to I-DATA (one of the Silver Queen's Artificial Intelligence utilities) the inhabitants of Delion practice several totemic religions in which each ethnic group is represented by a sacred animal. Other sources not confirmed by the Planetary Authority mention human sacrifices practiced by some of the most extreme sects. I'd better finish the job and leave here quickly.



08.42 GH

I-COM receives an encrypted transmission with the orbital coordinates where the payment will be made.



09.16 GH

I-NAV does not detect the presence of ships in the parking orbit agreed with the Delians. I wonder if this is a scam or a simple delay in the meeting.



09.23 GH

I-TAC Report-XXX

-"Three Vectra Class frigates detected on an interception course at 2.8 AU range".



09.24 GH

I-LEX Report-XXX

-"The government of Deliana Vorr notifies the death sentence for the crew of the ship Silver Queen TC-6745 because of the sacrilegious act committed against the Kaal".



09.25 GH

The "crew" of the Silver Queen has no time to curse that genetically deficient band who have implicated me in their absurd religious disputes. I proceed to activate the Emergency Voice-Controlled Orders protocol: "Tactical alert, asymmetric combat situation". A three-dimensional image of the star system immediately appears on the display, indicating the position of the three hostile spacecraft and a prediction of their future trajectories generated by I-TAC.





09.26 GH

The three frigates begin to maneuver aggressively. I-TAC informs that one of them will try to cut us off towards the Jump Zone while the other two separate to carry out a pincer attack. But they do not perform the maneuver correctly and one of them is delayed by unbalancing the formation.



09.27 GH

According to the coordinates that appear on the display the leading ship is the closest. I-COM has managed to identify it by deciphering its communications. I took my chance here: I pretended to flee to the planet, the lead ship turned to intercept me and inadvertently positioned itself between its No.2 and the Silver Queen.



09.28 GH

I managed to make both ships miss the opportunity to attack me simultaneously from two directions and I surprise my inexperienced aggressors diving straight into the Ise-73 star. It will be a race for survival. The Silver Queen weighs almost three times as much as a frigate and cannot compete with the propulsion system of a warship, but if I can get up to 0.24 AU from the star its immense gravitational attraction will turn the heaviest ship into the fastest one.



09.55 GH

The enemy begins to shorten distances, I-TAC predicts that the lead ship will reach the combat range at 0.53 AU. My only advantage is that both ships cannot shoot at me simultaneously because my last maneuver forced them to adopt a tandem configuration with 9,300 miles of separation between them.

My friend Stan Hope often says that retirement is overrated, if I don't come up with a good idea in the next twenty minutes I'll never know if the old man was right.



10.03 GH

I-TAC Report-XXX

-"Enemy at laser combat range ".

- The leader will fire at my propulsion system at any moment. I-TAC predicts that the effectiveness of his laser at that distance will be 44 percent.

The Crazy Mirror is a three-inch tall tetrahedron constructed of reflective polymer, having twelve triangular facets designed to reflect the maximum amount of light without getting too hot. The Silver Queen begins to eject a cloud of these objects through the ventral door starboard. Usually, the spacecraft only carries enough mirrors to make a single launch but for the last 39 minutes I-TECH has been manufacturing enough units to create a second protective cloud.



10.04 GH

The first shot is reflected by the cloud creating a radiant with one hundred thousand light beams that are totally harmless. In other circumstances it would have been a fantastic spectacle. I-TAC reports that the enemy is using a Type 132 laser. It is an outdated model that takes 30-45 seconds to cool down and recharge its capacitor after each shot.



10.07 GH

The leader is delaying the next shot until his No.2 reaches combat distance, his intention being that both ships fire simultaneously to magnify the destructive effect. But we also maneuver so that the lead frigate continues to stand between the Silver Queen and the No.2. It seems that I am facing a fan with a lot of desire to kill. If that guy were smarter he would slow down to pair up with No.2 and be able to coordinate the next attack.



10.09 GH

The second shot is cancelled out by our last reflective cloud. With all his sensors blinded by the luminous radiant, the leader cannot detect the six mines we have thrown behind the cloud of small mirrors.

The Thundermine has a warhead of the 11 MT yield class and the look of a matte black sphere with the size and weight of a bowling ball. Its short-range propulsion system is designed to reach great accelerations in three-tenths of a second.

The frigate disintegrates so quickly that No.2 has no time to avoid impact against the wreckage. The Stenman Field manages to absorb most of the shock wave but the speed of the ship is reduced by 31 percent.



10.15 GH

I-TAC Report-XXX

-"Enemy at M-63 energy weapons combat range".

- Sixty-five percent of the first discharge is absorbed by a cloud of magnetite particles launched from the Silver Queen, another thirty percent is absorbed by our Stenman Field but the fraction of energy that manages to pass through our defenses renders the starboard engine useless.



10.16 GH

I-TECH Report-XXX

-"Engine No.3 out of order, estimated repair time 130 minutes".

10.17 GH

-The enemy has not yet fired the second discharge, possibly waiting until it is closer to maximize the destructive effect of the M-63.

I-TAC Report-XXX

- "Enemy out of range with M-63".

-I do not understand what is happening, maybe their engines are failing with the effort of the chase.



10.18 GH

According to I-TAC the speed of the frigate has not decreased but the Silver Queen is now faster and continues to accelerate because of the gravitational attraction of Ise-73.



12.24 GH

The Silver Queen enters equatorial orbit around the star. We have won the race but not the fight. No.2 must coordinate a new pincer attack with the No.3.



12.25 GH

I-TECH Report-XXX

-"Repair of engine No. 3 completed".



12.26 GH

-Now the Silver Queen is faster than the frigates but if we try to reach the Jump Zone, they will have time to accelerate and catch up with us. They think we've lost one of the engines, but they are not able to locate us as long as we keep orbiting the star at close range because radiation blinds their instruments.



12.36 GH

Powered by the slingshot effect of the gigantic gravitational field, the spacecraft will reach its maximum speed when it has traveled half the orbit around Ise-73 and the enemies know that. No.2 will continue the blind chase and No.3 will intercept us as soon as he can detect us. The Silver Queen will not survive a frontal attack with energy weapons with her Stenmann Field weakened by radiation. I-NAV recommends abandoning the protection of the star at 16.45 GH, but it will be better that we do not stay so sunbathing for so. It can be harmful.



14.31 GH

With its three engines and the inertial dampers running at full power, the Silver Queen raises its nose to 45 degrees over the plane of the star system.

I-NAV has calculated the momentum needed to alter our orbital inclination so that we will leave the star after having traveled only a quarter of the orbit.



16.45 GH

We move away from Ise-73 in the direction of the Jump Zone following an oblique trajectory through the star system so that the star comes between our enemies and the Silver Queen. According to I-TAC the frigates will not be able to detect us before the jump, they will not even know that we have left. The enemy may believe that we have been destroyed by the failure of our Stenmann Field.