11 ms·

The Physics of Space War: How Orbital Dynamics Constrain Engagements [pdf]

125 points by sohkamyung 6y ago

Reelin 6y ago
> Its focus is only to help those of us bound to Earth understand the counterintuitive forces that drive movement and maneuver in space. In an alternate reality, mastery of Kerbal Space Program becomes a political qualification.
sxp 6y ago
If you want to try this out in video game form, I recommend https://store.steampowered.com/app/476530/Children_of_a_Dead_Earth/ https://store.steampowered.com/app/476530/Children_of_a_Dead... It's a more realistic space game than Kerbal Space Program and focuses on orbital combat. It does have a steep learning curve since it is literally rocket science, but if you've played KSP or other games with realistic orbital mechanics, you'll be able to pick up the core aspects easily.
- remarkEon 6y ago
  This game is _hard_, but definitely fun and worth getting into if you like realistic sims.
  - sharpneli 6y ago
    It can be hard at start. Then it becomes absolutely hilarious in the way one can break things. Custom designs are insanely more powerful than the builtin ones. Either design a fission plant with super high temp cooler side (to keep your radiators small) and then go full laser star or make sandblaster railguns. 1g nuggets of stuff blasted as fast as possible with ridiculous rate of fire simply ablate through any armor anyone can design. Or just design a gun that shoots guns that shoots guns that shoots guns that shoot nukes. The time when they didn't consider the pressure of tritium inside a nuke was hilarious. One could design a basic implosion nuke -> fill it with absolutely insane amount of tritium and make a few tens of kilos weighing 10 gigaton nuke or whatnot. And then just watch the fireworks. I really love that game. The shenanigans one can pull off.
- hypertexthero 6y ago
  Looks cool, will check it out — thanks! At first I thought the original post was about the first video game ever made, Spacewar!! Play Spacewar! online: https://www.masswerk.at/spacewar/ https://www.masswerk.at/spacewar/ A recent stream: https://www.youtube.com/watch?v=dD6cyXdXyzs https://www.youtube.com/watch?v=dD6cyXdXyzs
- Symmetry 6y ago
  Even without playing the game, the blog where the author goes through their research for the game is very worthwhile. https://childrenofadeadearth.wordpress.com/ https://childrenofadeadearth.wordpress.com/
- Symmetry 6y ago
  Oh, and if you want realistic space combat in tactical minis form let me recommend Attack Vector Tactical. https://www.adastragames.com/attack-vector-tactical https://www.adastragames.com/attack-vector-tactical They do some nifty things with letting you use kinetic to constrain the maneuver of your opponent so you can better employ your lasers, etc.
  - sxp 6y ago
    The tutorial PDF is available for free https://static1.squarespace.com/static/5470f0aae4b08efc8c773f95/t/547e1f02e4b06b55ee060f7a/1417551618895/AVT_Tutorial.pdf https://static1.squarespace.com/static/5470f0aae4b08efc8c773... It provides a good intro on how to deal with 3D vectors in a 2D boardgame
gregmac 6y ago
If you haven't read the books or watched the show, The Expanse does a great job at working in a world with realistic physics. A lot of combat takes place from extremely far distances, using telescopes, rail guns and missiles, and it can sometimes take days for a missile to reach the target (the TV series doesn't play this up as much though, for obvious reasons). When there is closer combat battles, they are constrained by the G forces humans can tolerate, wear full helmets and de-pressurize their ships, so when the inevitable shots do go through (usually in and out the other side) it's not catastrophic. There are no force shields, magic gravity generators, lasers (well, except used for point-to-point communications). I found it to be very refreshing mainstream sci-fi. One warning: after watching The Expanse, the battles in things like Star Wars, Star Trek or Battlestar just look ridiculous by comparison - even with that technology they'd never fight like that.
- garmaine 6y ago
  Not to take away from your post, because I largely agree, but the Epstein drive might as well be magic. In no realistic universe are there large battle cruisers zipping around the solar system under constant 1G (or even Mars’ third-G) acceleration for months at a time. But aside from that and the whole aliens technology thing the plot revolves around, it is very realistic. They certainly get a lot closer than anybody else.
  - saberdancer 6y ago
    Physics is realistic, engineering not so much? :)
  - ivalm 6y ago
    I am not sure how unreasonable is prolonged 1g. You can’t do it for months (since if it’s all in one direction you will start getting relativistic, one month of 1g gets you to almost 0.1c) but at medium speeds it isn’t too bad. Suppose you have a megaton ship moving at 100km/s with 10 m/s^2 acceleration Power = m v a = 1e9 x 1e5 x 1e1 = 1e15 W While petawatt is a lot, a megaton ship is also huge. Epstein drive is a fusion drive of sort, the easiest aneutronic reaction would be B+p -> C + 16 MeV So 2.5e-12 Joules per fusion Which means you need to burn 1e15 J/s /(2.5e-12 J/atom)*(2e-26 kg/atom) = 8 kg/s Suppose your engine runs at 10% efficiency, it means you are powering a megaton ship on less than a 100kg/s of material. So if your megaton ship starts as 10% fuel you have ~115 days of continuous thrust.
tehjoker 6y ago
This is kind of tangential, but I recently played CoD: Ghosts (2013) for the first time and there was a lot of cool space war in it. I found however that its level of... not realism, but feeling real made me depressed. Space was supposed to be for peaceful exploration and we want to put a bunch of meat head killers or killing tools up there. It made me feel profoundly sad that there is now an official military branch dedicated to this stuff even though it was going on before to various extents.
- kortilla 6y ago
  Very little of what a modern military does is “meat heat killers with killing tools”. Critical things like tracking space junk and ensuring the safe launch of rockets is the job of the military. You just might not have noticed because it’s not a meathead with a gun.
  - tehjoker 6y ago
    That's a job that could be done by a civilian agency. You also may be missing the point that the military does much of that support role stuff in preparation for using lethal force, which they are not shy about.
    - kortilla 6y ago
      > That's a job that could be done by a civilian agency. So could all of the military if you want to go down that path. There is nothing special that makes something “military only”. Cops are civilians as are secret service and members of the CIA and they kill people on and off US soil.
ogennadi 6y ago
And for a fictional treatment of realistic space battles, read "Through Struggle, the Stars" by John Lumpkin. I skipped lots of the story sections so I could get to the space fights
zelienople 6y ago
There is something terribly wrong with a species who, in the infancy of their space travel, spends so much time and effort considering the matter of making war in space.
- mclightning 6y ago
  in comparison to which other species?
  - filoeleven 6y ago
    The Daleks. They spend no time at all considering war, they just get on with it.
- HelloNurse 6y ago
  A species that, in the mature age of their warfare, spends so much time and effort considering the matter of extending war to a new location.
  - dustingetz 6y ago
    acting in an inexploitable way is a nash equilibrium or do we think the aliens don’t understand game theory or evolved without a survival instinct?
- ddxxdd 6y ago
  To make peace you must prepare for war. Also, it's better to be a warrior in a garden than a gardener in a war.
  - kybernetikos 6y ago
    For a particular definition of 'better' that probably involves survival but not ethics.
- NikolaeVarius 6y ago
  Literally anything in space almost by definition is a weapon. Blame physics.
chuckleMuscle 6y ago
I'm curious what the motivation for putting this report together was. Some ideas: - Create interest in company to aid recruitment - For fun - Client paid them to do this (seems unlikely) Any thoughts?
- HelloNurse 6y ago
  Preemptive education of the next politician who wants to knock out a "hostile" satellite.
- ddxxdd 6y ago
  Intellectual curiosity? Similar to Nobel Laureate economist Paul Krugman opined about special relativity's impact on interstellar interest rates?
- peterwoerner 6y ago
  It's technical advertising and probably they wrote it as part of a bigger project which a customer paid them to do it. If you wrote the white paper which was used to teach the officer. The officer is going to assume technical competence and better trust you on other technical aspects.
- panzagl 6y ago
  Probably to present at the Space Symposium which would have been in a week. Gotta release it now so it looks like you did something in FY 2020.
neural_thing 6y ago
See also: https://www.gwern.net/Colder-Wars https://www.gwern.net/Colder-Wars
wespiser_2018 6y ago
What kills about shows like Battlestar Gallactica is that they have no sense of how tactics would evolve in new environment, and instead transpose modern era fighter and air craft carrier tactics in a total new environment. For instance, If you have an FTL, and know a targets location, why wouldn't you jump, shoot everything you have, then jump away? The entire game changes with FTL, and it would be really cool to see that explored in Hard-sci.
- kybernetikos 6y ago
  If you have FTL ships, why don't you have FTL weapons, which would be entirely undetectable before they hit (except by FTL observation?).

125 points by sohkamyung 6y ago

> Its focus is only to help those of us bound to Earth understand the counterintuitive forces that drive movement and maneuver in space. In an alternate reality, mastery of Kerbal Space Program becomes a political qualification.

sxp 6y ago

If you want to try this out in video game form, I recommend https://store.steampowered.com/app/476530/Children_of_a_Dead_Earth/ https://store.steampowered.com/app/476530/Children_of_a_Dead... It's a more realistic space game than Kerbal Space Program and focuses on orbital combat. It does have a steep learning curve since it is literally rocket science, but if you've played KSP or other games with realistic orbital mechanics, you'll be able to pick up the core aspects easily.

remarkEon 6y ago
This game is _hard_, but definitely fun and worth getting into if you like realistic sims.
- sharpneli 6y ago
  It can be hard at start. Then it becomes absolutely hilarious in the way one can break things. Custom designs are insanely more powerful than the builtin ones. Either design a fission plant with super high temp cooler side (to keep your radiators small) and then go full laser star or make sandblaster railguns. 1g nuggets of stuff blasted as fast as possible with ridiculous rate of fire simply ablate through any armor anyone can design. Or just design a gun that shoots guns that shoots guns that shoots guns that shoot nukes. The time when they didn't consider the pressure of tritium inside a nuke was hilarious. One could design a basic implosion nuke -> fill it with absolutely insane amount of tritium and make a few tens of kilos weighing 10 gigaton nuke or whatnot. And then just watch the fireworks. I really love that game. The shenanigans one can pull off.
hypertexthero 6y ago
Looks cool, will check it out — thanks! At first I thought the original post was about the first video game ever made, Spacewar!! Play Spacewar! online: https://www.masswerk.at/spacewar/ https://www.masswerk.at/spacewar/ A recent stream: https://www.youtube.com/watch?v=dD6cyXdXyzs https://www.youtube.com/watch?v=dD6cyXdXyzs
Symmetry 6y ago
Even without playing the game, the blog where the author goes through their research for the game is very worthwhile. https://childrenofadeadearth.wordpress.com/ https://childrenofadeadearth.wordpress.com/
Symmetry 6y ago
Oh, and if you want realistic space combat in tactical minis form let me recommend Attack Vector Tactical. https://www.adastragames.com/attack-vector-tactical https://www.adastragames.com/attack-vector-tactical They do some nifty things with letting you use kinetic to constrain the maneuver of your opponent so you can better employ your lasers, etc.
- sxp 6y ago
  The tutorial PDF is available for free https://static1.squarespace.com/static/5470f0aae4b08efc8c773f95/t/547e1f02e4b06b55ee060f7a/1417551618895/AVT_Tutorial.pdf https://static1.squarespace.com/static/5470f0aae4b08efc8c773... It provides a good intro on how to deal with 3D vectors in a 2D boardgame

gregmac 6y ago

If you haven't read the books or watched the show, The Expanse does a great job at working in a world with realistic physics. A lot of combat takes place from extremely far distances, using telescopes, rail guns and missiles, and it can sometimes take days for a missile to reach the target (the TV series doesn't play this up as much though, for obvious reasons). When there is closer combat battles, they are constrained by the G forces humans can tolerate, wear full helmets and de-pressurize their ships, so when the inevitable shots do go through (usually in and out the other side) it's not catastrophic. There are no force shields, magic gravity generators, lasers (well, except used for point-to-point communications). I found it to be very refreshing mainstream sci-fi. One warning: after watching The Expanse, the battles in things like Star Wars, Star Trek or Battlestar just look ridiculous by comparison - even with that technology they'd never fight like that.

garmaine 6y ago
Not to take away from your post, because I largely agree, but the Epstein drive might as well be magic. In no realistic universe are there large battle cruisers zipping around the solar system under constant 1G (or even Mars’ third-G) acceleration for months at a time. But aside from that and the whole aliens technology thing the plot revolves around, it is very realistic. They certainly get a lot closer than anybody else.
- saberdancer 6y ago
  Physics is realistic, engineering not so much? :)
- ivalm 6y ago
  I am not sure how unreasonable is prolonged 1g. You can’t do it for months (since if it’s all in one direction you will start getting relativistic, one month of 1g gets you to almost 0.1c) but at medium speeds it isn’t too bad. Suppose you have a megaton ship moving at 100km/s with 10 m/s^2 acceleration Power = m v a = 1e9 x 1e5 x 1e1 = 1e15 W While petawatt is a lot, a megaton ship is also huge. Epstein drive is a fusion drive of sort, the easiest aneutronic reaction would be B+p -> C + 16 MeV So 2.5e-12 Joules per fusion Which means you need to burn 1e15 J/s /(2.5e-12 J/atom)*(2e-26 kg/atom) = 8 kg/s Suppose your engine runs at 10% efficiency, it means you are powering a megaton ship on less than a 100kg/s of material. So if your megaton ship starts as 10% fuel you have ~115 days of continuous thrust.

tehjoker 6y ago

This is kind of tangential, but I recently played CoD: Ghosts (2013) for the first time and there was a lot of cool space war in it. I found however that its level of... not realism, but feeling real made me depressed. Space was supposed to be for peaceful exploration and we want to put a bunch of meat head killers or killing tools up there. It made me feel profoundly sad that there is now an official military branch dedicated to this stuff even though it was going on before to various extents.

kortilla 6y ago
Very little of what a modern military does is “meat heat killers with killing tools”. Critical things like tracking space junk and ensuring the safe launch of rockets is the job of the military. You just might not have noticed because it’s not a meathead with a gun.
- tehjoker 6y ago
  That's a job that could be done by a civilian agency. You also may be missing the point that the military does much of that support role stuff in preparation for using lethal force, which they are not shy about.
  - kortilla 6y ago
    > That's a job that could be done by a civilian agency. So could all of the military if you want to go down that path. There is nothing special that makes something “military only”. Cops are civilians as are secret service and members of the CIA and they kill people on and off US soil.

ogennadi 6y ago

And for a fictional treatment of realistic space battles, read "Through Struggle, the Stars" by John Lumpkin. I skipped lots of the story sections so I could get to the space fights

zelienople 6y ago

There is something terribly wrong with a species who, in the infancy of their space travel, spends so much time and effort considering the matter of making war in space.

mclightning 6y ago
in comparison to which other species?
- filoeleven 6y ago
  The Daleks. They spend no time at all considering war, they just get on with it.
HelloNurse 6y ago
A species that, in the mature age of their warfare, spends so much time and effort considering the matter of extending war to a new location.
- dustingetz 6y ago
  acting in an inexploitable way is a nash equilibrium or do we think the aliens don’t understand game theory or evolved without a survival instinct?
ddxxdd 6y ago
To make peace you must prepare for war. Also, it's better to be a warrior in a garden than a gardener in a war.
- kybernetikos 6y ago
  For a particular definition of 'better' that probably involves survival but not ethics.
NikolaeVarius 6y ago
Literally anything in space almost by definition is a weapon. Blame physics.

chuckleMuscle 6y ago

I'm curious what the motivation for putting this report together was. Some ideas: - Create interest in company to aid recruitment - For fun - Client paid them to do this (seems unlikely) Any thoughts?

HelloNurse 6y ago
Preemptive education of the next politician who wants to knock out a "hostile" satellite.
ddxxdd 6y ago
Intellectual curiosity? Similar to Nobel Laureate economist Paul Krugman opined about special relativity's impact on interstellar interest rates?
peterwoerner 6y ago
It's technical advertising and probably they wrote it as part of a bigger project which a customer paid them to do it. If you wrote the white paper which was used to teach the officer. The officer is going to assume technical competence and better trust you on other technical aspects.
panzagl 6y ago
Probably to present at the Space Symposium which would have been in a week. Gotta release it now so it looks like you did something in FY 2020.

neural_thing 6y ago

See also: https://www.gwern.net/Colder-Wars https://www.gwern.net/Colder-Wars

wespiser_2018 6y ago

What kills about shows like Battlestar Gallactica is that they have no sense of how tactics would evolve in new environment, and instead transpose modern era fighter and air craft carrier tactics in a total new environment. For instance, If you have an FTL, and know a targets location, why wouldn't you jump, shoot everything you have, then jump away? The entire game changes with FTL, and it would be really cool to see that explored in Hard-sci.

kybernetikos 6y ago
If you have FTL ships, why don't you have FTL weapons, which would be entirely undetectable before they hit (except by FTL observation?).