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.