Anti-Orbit Laser Submarines (2017) | Hacker News Reader

Anti-Orbit Laser Submarines (2017)

toughsf.blogspot.com

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The supercavitating supersonic submarine is a nice endpoint for the evasion discussion but I can't help thinking about the wake that would leave.

Yes it can depart the firing area quickly but if one wanted to find it again for counterfire, surely the point where the absurd wake turbulence ends is a suitable search datum.

Presumably an opponent with capable spaceships can spare the power required for scans along these principles: https://www.sciencedirect.com/science/article/abs/pii/S09242...

Cool idea. Atmospheric attenuation (regardless even if you lase at "transmissible" freqs), would be a major issue. Additionally, beam steering and focusing from 1000km+, and accounting (essentially a variable continuously changing integration) for a high variability in index of refraction would make it possible without a closed-loop feedback of on target strike. Rough ballparks, I mean, the beam power density required would likely far exceed the thermal dissipation rate of any heat pipe, etc, tech I am officially aware of. Space warfare is super fun tho. However, this is a very outdated idea. If anyone like noodling on this stuff, they should DM me. There are far better ideas... unofficially.

FYI there's no way to DM you on HN unless you leave some contact info on your profile, which may or may not be in the form of a puzzle.

>> Atmospheric attenuation

You start with the adaptive optics used in many telescopes. For whatever angular resolution an earth-based telescope can accomplish, that same tech can probably also focus a laser beam to a similar degree.

(Adaptive optics largely started from laser weapon programs, only later being used for astronomy.)

https://en.wikipedia.org/wiki/Boeing_YAL-1

Share with the class. I'm not sliding into anyone's DMs, even for space warfare

Interesting thought experiment. Some questions:

- couldn’t the submarine have some sort of extendable trunk to avoid the loss of laser energy in water? Basically a much longer periscope?

- the RASER principle seems to be much easier to deploy from space, where large dishes are simple to deploy, potentially offsetting reactor cooling disadvantages, and mitigate the protective effect of water?

- are 10-20 Meters of water really enough to protect against kinetic weapons?

I think this article undersells the size of the antenna needed to focus a powerful radio source into a distant target.

> couldn’t the submarine have some sort of extendable trunk to avoid the loss of laser energy in water? Basically a much longer periscope?

I'm put in mind of the mirror on a stick in Saving Private Ryan

I don’t think I have ever spent so long trying to understand the physics of destroying an invading alien spaceship.

Isn't it fun to noodle on? lol

Independence day had the right idea. Just inflict windows ME on them via a convenient day-18250 vulnerability

The article doesn't make any mention of stealth. I think stealth would be a key factor in any serious future space war. On general physics principles, it's not difficult to make a space object with close to zero emissions in a specified direction. The inverse-square law is a helpful ally. Active (i.e. radar or lidar) have rapidly diminishing returns: their signal powers scale as distance^{-4}—doubly inverse-square.

I'm not sure what response can be invented against a dark space object that shoots dark stealth warheads that detonate in the upper atmosphere.

A dark space object can be seen when it passes between the observer and stars or other objects, so you need to match the spectrum behind you, which makes it a much harder problem!

Being very cold is good for long range stealth, but in low orbit the speeds are high enough that it doesn't help against a savvy adversary.

- "A dark space object can be seen when it passes between the observer and stars or other objects,"

Those are called transits. They're extraordinarily rare for any single given object. Moreover, there are quadrillions of natural objects transiting stars as a baseline noise rate, which you'd be hard-pressed to distinguish a spacecraft from. One hiding among quadrillions.

Even if you were very lucky and both observed, and identified, a spacecraft transiting a star, you've instantly lost it. You would need multiple transits in close succession to recover an orbit (and predict its future positions), something which will statistically never happen.

If you have a number of anti-orbit laser submarines, I suspect a global network of observer stations that are passively looking for transits that don't have a known source is within your budget

That doesn't help, since multiple transits are a statistical impossibility no matter how many observers you have.

- "for transits that don't have a known source"

That's statistically about 100% of them: small, remote asteroids or interstellar objects that have never been catalogued, and are undetectable except via transits.

There is no stealth in space.

https://www.projectrho.com/public_html/rocket/spacewardetect...

That page isn't really responsive to my comment. I'm not sure what point you're trying to make!

Of course if you point a directional radio transmitter at an observer, you are not being stealthy, to that observer.

Of course if you power up a 100 gigawatt incandescent rocket motor, you're loudly advertising your presence. (No different than a stealth aircraft using afterburners—they don't). Stealth spacecraft would necessarily avoid doing that. Stealth spacecraft could, to highlight one option from a large decision space, consider cryogenic, cold-gas thrusters with invisible output plumes and zero infrared emissions.

Did you even read the whole page? Using cold gas thrusters doesn't solve anything, especially not if you have a crew on board.

The goal of actual spacewar is to make a auto railgun bullet hell with near c pellets from outside the system, then move in with railgun drones to lure your opponent into the rain or redirect the rain were the opponent will be forced to go. not to dissimilar to 3d flak.

I've always wondered why we don't have remote controlled zeppelins yet. Seems like the perfect platform for drones. Use hydrogen inside the zeppelin and for a fuel cell module.

Probably too slow, easy to detect and shoot down.

HN, where one story is about hypothetical submarine spaceship laser battles, and the next is about usb-ps2 mouse port adapters, and you want to read them both.

Dear god, they firing a laser again.. activate the water pumps.. its all steam outside.. the dread.. the horror.. now we dive, and its all surface steam. Oh, the fish-manity.

They burned away one layer of glycol shield plating. Horrific.

Oh, they use x-ray lasers- but the platform that comes up to fire, is hardened, automated, a shooter, that returns to the depths.

> Oh, the fish-manity

I'm glad I wasn't drinking anything when I read this because it would be coming out my nose about now

It's not a joke, in the '60s they considered Lazer Submarines but the technology wasn't scalable at that time, a lazer weapon usually would be backpack size. At the time the US Navy began developing a secret project which is Lazer Dolphins. The Soviet got wind of this and worried about the Lazer Arms Race Gap, so they begin to develop Lazer Sharks. Of course that isn't the end of the whole Lazer arms race, in modern times there have been efforts to use genetic technology to resurrect ancient organisms to mount Lazers upon. For example, China is developing Lazer Raptors currently, and Russia has announced several wonder weapons including a nuclear rocket engine ICBM, a submarine-sized fusion bomb drone torpedo, and Lazer Mammoths.

There's a similar concept in the Battletech universe. The Lowyfur, a Wyrm-class submersible SDS, evaded capture for 5 years after the liberation of Terra, continuing to prowl the oceans and inflict Blakist terror. https://www.sarna.net/wiki/Wyrm_SDS_Submersible_Fortress

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