4 ms·

Three things: 1) That way you would have a single Starship launching a single kill vehicle in more than 1000 pieces. In order to be truly independent, each kil

Three things: 1) That way you would have a single Starship launching a single kill vehicle in more than 1000 pieces. In order to be truly independent, each kill vehicle needs significant delta-v on its own, which lowers the number of kill vehicles by two orders of magnitude. 2) Starship has pretty weak engines for this task. While the missile used to launch the Exoatmospheric Kill Vehicle reaches ~10 km/s in less than 4 minutes, Starship launch profile suggests 8 km/s in ~9 minutes. When a nuclear strike is incoming, you don't have those minutes to waste. 3) Starship uses liquid fuel, which means it can't wait on the launchpad ready to launch at a moment's notice very long. Missiles use solid fuels for a reason.

georgeg23 4y ago
The kill vehicles are staged in orbit just like Starlink satellites.. See Brilliant Pebbles.
- wmf 4y ago
  I think there's a consensus that orbital weapons are bad.
  - GekkePrutser 4y ago
    Even if they're defensive weapons only? I think Reagan's star wars program was cancelled only because the Russian threat was not as big anymore. Not because of weapons in space concerns. FWIW only WMDs are really banned in space.
    - georgeg23 4y ago
      Democrats / Clinton shut down the original Star Wars program because they favored arms control (arguing Star Wars was illegal under the Anti Ballistic Missile Treaty) That treaty expired in 2002 and then Elon went to Russia to buy some ICBMs...
      - Throwawayaerlei 4y ago
        The Anti-Ballistic Missile Treaty was a Nixon-Brezhnev 1972 thing, albeit ratified by a Democratic Senate in the same year: https://en.wikipedia.org/wiki/Anti-Ballistic_Missile_Treaty https://en.wikipedia.org/wiki/Anti-Ballistic_Missile_Treaty
        georgeg23 4y ago
        Yes Good recent discussion: https://carnegieendowment.org/2021/12/16/approaching-third-rail-trilateral-treaty-to-prohibit-space-based-missile-defenses-pub-85965 https://carnegieendowment.org/2021/12/16/approaching-third-r...
      - adgjlsfhk1 4y ago
        They also shut down star wars because it relied on magic that didn't exist. Raegan was a big fan of big projects that didn't make technical sense (see also the SSC)
      - candiodari 4y ago
        Do "kill vehicles" that are only capable of destroying a few tens of square meters at best really illegal under the ballistic missile treaty?
    - ilyt 4y ago
      > Even if they're defensive weapons only? And how you are going to convince everyone else that they are "just" defensive weapons ?
  - georgeg23 4y ago
    Apparently Republicans are all for weapons in space... https://www.science.org/content/article/decades-after-reagan-s-star-wars-trump-calls-missile-defenses-would-blast-warheads-sky https://www.science.org/content/article/decades-after-reagan... https://nationalinterest.org/feature/nuclear-weapons-china-and-strategic-century-199549 https://nationalinterest.org/feature/nuclear-weapons-china-a...
  - t-3 4y ago
    Weapons are bad in general. The military, however, takes a practical view rather than a moral one, and will not limit themselves based on what is good and bad, but will arm themselves based on what is effective. This is why we can't have nice things.
    - wmf 4y ago
      I was thinking more like game theoretically bad.
      - t-3 4y ago
        They may be bad in some game theory way, I don't know the argument, but large groups of humans are very much not rational actors. The tendency is to oppose the enemy rather than to maximize gains or minimize losses.
  - DocTomoe 4y ago
    The biggest CO2 polluter in the world is ... the US Military. What makes you think they won't clutter up space with weapons?
- skorpeon87 4y ago
  You're talking about boost-phase interceptors, not mid-course interceptors. Starship to replace GMD (as suggested by credit_guy) doesn't make much sense, but Starship does have the technical ability to launch a massive constellation of space-based interceptors for quite cheap. With Starship, it should be possible to put tens of thousands of interceptors into LEO, and to rapidly replenish the constellation. As for the "general consensus that weapons in space are bad", there's also a general consensus that war is bad, so we should all breath easy! Wait no.
  - rocqua 4y ago
    The problem with weapons in space are that they put the opposing super-powers in an impossible position. Hence it forces them to make a move asap to prevent being at a total disadvantage. This is mostly because weapons in space can be used with very little warning. There is little defense, and not even any notice that allows you to prepare or setup a second strike. Plenty of people don't think that's bad, but it seems that the top military decision makers of all super-powers do see the problem with that, and hence they have managed to keep weapons out of space. This remains a high-level decision, so it only takes a few rational people for the game-theory to work. Consider the external politics around mobilization. It is a big deal to mobilize externally, because it forces opposing players to also mobilize, hence moving everyone closer to conflict. The thing about weapons in space is that they are effectively always mobilized. Even if you could sustain perpetual mobilization, it wouldn't be a good strategic move. Something similar goes for missile defense systems that are too effective. It disrupts MAD, and pushes the opposing side in to a corner. Either make a move before the defense system is up, or accept a role as a second grade power from now on. The problem, specifically, is that it removes the second-strike capability much more than that it removes the first-strike capability. So having a missile-defense system in orbit has game-theoretical downsides both for being in space, and for removing the enemies second-strike capability. The same does not quite hold for having the capability to launch such a missile defense system. It gives your opponent time to react when you launch it. Hence they do not need to immediately react to you having the capability. So I think research into this area, preparations, and development of the system are fine. Heck it is even important and desirable. We just need to continuously refuse to even ready such systems outside of well-announced and limited tests.
credit_guy 4y ago
1. Not sure what you mean by significant delta-v. An 8km/s vehicle meeting a 6km/s warhead coming from the opposite direction will kill it just as surely as a 10km/s one. If you mean delta-v to go laterally, for that 1km/s is probably more than enough. A vehicle with 1km/s delta-v is, in the worst case scenario, twice as heavy than one with 100m/s delta-v, not 100 times as heavy. 2. 9 minutes is plenty. A ballistic missile takes about 30 min to go from one continent to another. The difference between 4 min and 9 min is not a make or break thing. 3. Everything has a price. If a single GBI booster costs north of $50 mil, then you can afford to spend a few tens of millions to keep fully fueled Starships on the launchpad, 24/7/365. From time to time you'd have to empty them, and move them an give them a thorough inspection. It can be done. 4. (bonus) If things get tense, a Starship could also carry a few hundred MIRVs. China thinks it can sprint forward in the arms race at a certain point. They'll find out it's not going to be that easy.
- jltsiren 4y ago
  1. This is just basic orbital mechanics. Multiple missiles are launched from different locations at different targets. The launches are not fully simultaneous. Each kill vehicle must be at the right place at the right time to intercept its target. If you launch all kill vehicles from the same location at the same time, the differences between the required velocity vectors are easily several km/s. 2. The midcourse phase typically takes ~20 minutes. You can't predict the trajectory accurately during the boost phase, and you have the wrong kind of missile for intercepting the target during the terminal phase. If your boost phase is 9 minutes instead of 4 minutes, you have 11 minutes instead of 16 minutes for political and tactical decisionmaking. 3. What is the price of a fully disposable Starship? How many of them do you need to have one ready to launch at any time? Because if you have them on standby, you can't use them for any other purpose, and they are effectively disposable.
  - credit_guy 4y ago
    > What is the price of a fully disposable Starship? Musk aims to get the cost of building one Starship to $5 million [1]. That sounds insane, I know, but he also aims to build about 1000 of them. When you get to this scale of mass production, efficiencies of scale kick in. Could he be wrong. I suppose so, but even if he's wrong by a factor of 10 or 20, it would still provide a tremendous value proposition for an Anti Ballistic Defense system. [1] https://arstechnica.com/science/2020/03/inside-elon-musks-plan-to-build-one-starship-a-week-and-settle-mars/ https://arstechnica.com/science/2020/03/inside-elon-musks-pl...

georgeg23 4y ago

The kill vehicles are staged in orbit just like Starlink satellites.. See Brilliant Pebbles.

wmf 4y ago
I think there's a consensus that orbital weapons are bad.
- GekkePrutser 4y ago
  Even if they're defensive weapons only? I think Reagan's star wars program was cancelled only because the Russian threat was not as big anymore. Not because of weapons in space concerns. FWIW only WMDs are really banned in space.
  - georgeg23 4y ago
    Democrats / Clinton shut down the original Star Wars program because they favored arms control (arguing Star Wars was illegal under the Anti Ballistic Missile Treaty) That treaty expired in 2002 and then Elon went to Russia to buy some ICBMs...
    - Throwawayaerlei 4y ago
      The Anti-Ballistic Missile Treaty was a Nixon-Brezhnev 1972 thing, albeit ratified by a Democratic Senate in the same year: https://en.wikipedia.org/wiki/Anti-Ballistic_Missile_Treaty https://en.wikipedia.org/wiki/Anti-Ballistic_Missile_Treaty
      - georgeg23 4y ago
        Yes Good recent discussion: https://carnegieendowment.org/2021/12/16/approaching-third-rail-trilateral-treaty-to-prohibit-space-based-missile-defenses-pub-85965 https://carnegieendowment.org/2021/12/16/approaching-third-r...
    - adgjlsfhk1 4y ago
      They also shut down star wars because it relied on magic that didn't exist. Raegan was a big fan of big projects that didn't make technical sense (see also the SSC)
    - candiodari 4y ago
      Do "kill vehicles" that are only capable of destroying a few tens of square meters at best really illegal under the ballistic missile treaty?
  - ilyt 4y ago
    > Even if they're defensive weapons only? And how you are going to convince everyone else that they are "just" defensive weapons ?
- georgeg23 4y ago
  Apparently Republicans are all for weapons in space... https://www.science.org/content/article/decades-after-reagan-s-star-wars-trump-calls-missile-defenses-would-blast-warheads-sky https://www.science.org/content/article/decades-after-reagan... https://nationalinterest.org/feature/nuclear-weapons-china-and-strategic-century-199549 https://nationalinterest.org/feature/nuclear-weapons-china-a...
- t-3 4y ago
  Weapons are bad in general. The military, however, takes a practical view rather than a moral one, and will not limit themselves based on what is good and bad, but will arm themselves based on what is effective. This is why we can't have nice things.
  - wmf 4y ago
    I was thinking more like game theoretically bad.
    - t-3 4y ago
      They may be bad in some game theory way, I don't know the argument, but large groups of humans are very much not rational actors. The tendency is to oppose the enemy rather than to maximize gains or minimize losses.
- DocTomoe 4y ago
  The biggest CO2 polluter in the world is ... the US Military. What makes you think they won't clutter up space with weapons?
skorpeon87 4y ago
You're talking about boost-phase interceptors, not mid-course interceptors. Starship to replace GMD (as suggested by credit_guy) doesn't make much sense, but Starship does have the technical ability to launch a massive constellation of space-based interceptors for quite cheap. With Starship, it should be possible to put tens of thousands of interceptors into LEO, and to rapidly replenish the constellation. As for the "general consensus that weapons in space are bad", there's also a general consensus that war is bad, so we should all breath easy! Wait no.
- rocqua 4y ago
  The problem with weapons in space are that they put the opposing super-powers in an impossible position. Hence it forces them to make a move asap to prevent being at a total disadvantage. This is mostly because weapons in space can be used with very little warning. There is little defense, and not even any notice that allows you to prepare or setup a second strike. Plenty of people don't think that's bad, but it seems that the top military decision makers of all super-powers do see the problem with that, and hence they have managed to keep weapons out of space. This remains a high-level decision, so it only takes a few rational people for the game-theory to work. Consider the external politics around mobilization. It is a big deal to mobilize externally, because it forces opposing players to also mobilize, hence moving everyone closer to conflict. The thing about weapons in space is that they are effectively always mobilized. Even if you could sustain perpetual mobilization, it wouldn't be a good strategic move. Something similar goes for missile defense systems that are too effective. It disrupts MAD, and pushes the opposing side in to a corner. Either make a move before the defense system is up, or accept a role as a second grade power from now on. The problem, specifically, is that it removes the second-strike capability much more than that it removes the first-strike capability. So having a missile-defense system in orbit has game-theoretical downsides both for being in space, and for removing the enemies second-strike capability. The same does not quite hold for having the capability to launch such a missile defense system. It gives your opponent time to react when you launch it. Hence they do not need to immediately react to you having the capability. So I think research into this area, preparations, and development of the system are fine. Heck it is even important and desirable. We just need to continuously refuse to even ready such systems outside of well-announced and limited tests.

credit_guy 4y ago

1. Not sure what you mean by significant delta-v. An 8km/s vehicle meeting a 6km/s warhead coming from the opposite direction will kill it just as surely as a 10km/s one. If you mean delta-v to go laterally, for that 1km/s is probably more than enough. A vehicle with 1km/s delta-v is, in the worst case scenario, twice as heavy than one with 100m/s delta-v, not 100 times as heavy. 2. 9 minutes is plenty. A ballistic missile takes about 30 min to go from one continent to another. The difference between 4 min and 9 min is not a make or break thing. 3. Everything has a price. If a single GBI booster costs north of $50 mil, then you can afford to spend a few tens of millions to keep fully fueled Starships on the launchpad, 24/7/365. From time to time you'd have to empty them, and move them an give them a thorough inspection. It can be done. 4. (bonus) If things get tense, a Starship could also carry a few hundred MIRVs. China thinks it can sprint forward in the arms race at a certain point. They'll find out it's not going to be that easy.

jltsiren 4y ago
1. This is just basic orbital mechanics. Multiple missiles are launched from different locations at different targets. The launches are not fully simultaneous. Each kill vehicle must be at the right place at the right time to intercept its target. If you launch all kill vehicles from the same location at the same time, the differences between the required velocity vectors are easily several km/s. 2. The midcourse phase typically takes ~20 minutes. You can't predict the trajectory accurately during the boost phase, and you have the wrong kind of missile for intercepting the target during the terminal phase. If your boost phase is 9 minutes instead of 4 minutes, you have 11 minutes instead of 16 minutes for political and tactical decisionmaking. 3. What is the price of a fully disposable Starship? How many of them do you need to have one ready to launch at any time? Because if you have them on standby, you can't use them for any other purpose, and they are effectively disposable.
- credit_guy 4y ago
  > What is the price of a fully disposable Starship? Musk aims to get the cost of building one Starship to $5 million [1]. That sounds insane, I know, but he also aims to build about 1000 of them. When you get to this scale of mass production, efficiencies of scale kick in. Could he be wrong. I suppose so, but even if he's wrong by a factor of 10 or 20, it would still provide a tremendous value proposition for an Anti Ballistic Defense system. [1] https://arstechnica.com/science/2020/03/inside-elon-musks-plan-to-build-one-starship-a-week-and-settle-mars/ https://arstechnica.com/science/2020/03/inside-elon-musks-pl...