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According to a National Academy of Sciences study, the intercept can happen within a couple minutes if the satellite deploying the interceptor is over the enemy

According to a National Academy of Sciences study, the intercept can happen within a couple minutes if the satellite deploying the interceptor is over the enemy territory launching the ICBM.. https://nap.nationalacademies.org/catalog/13189/making-sense-of-ballistic-missile-defense-an-assessment-of-concepts https://nap.nationalacademies.org/catalog/13189/making-sense... (Sorry you have to login as guest to download the PDF) This compares to ~20-30min for existing ICBMs and their ground based interceptors

hollerith 2y ago
The sentence I am criticizing is not about interception of ICBMs, so your link is not relevant. In particular, when the goal is to intercept an ICBM, the enemy helpfully raises the target to be (briefly) at the same altitude as the satellite. (An ICBM's max altitude is much higher than low-earth orbit.) If the goal is for a satellite to attack a city, the enemy does not helpfully raise the city to orbital altitudes.
- throw9474 2y ago
  I think the idea is in an arms race, if you can't launch ICBM nukes anymore (because of Musk's orbital interceptors) then you have to pre-launch nukes into orbit. THOSE nukes can then strike faster than ICBMs (just like interceptors can).
  - hollerith 2y ago
    I understood the we were talking about "pre-launching" nukes into orbit. I also understand that those nukes regularly get deliciously close to their targets (100 miles or so) (delicious from the point of view of the attacker). I stand by my assertion however: to be explicit, for the same energy budget, it is quicker to hit a target from the ground half-way around the world from the target than it is to hit the target from orbit even if the satellite is directly above the target. The exception to that is laser weapons because a laser beam has no momentum whereas all the "strategic" nukes in the US arsenal weigh at least 200 lb, which is a lot of momentum when moving at orbital speed. (Also, it is vastly cheaper to maintain infrastructure on the ground than in orbit.)
    - georgeg23 2y ago
      The satellite can deploy a hypersonic glide vehicle and utilize it's orbital velocity to manueve within the atmosphere. See Fractional Orbital Bombardment. China tested theirs last year. ...SpaceX people are building it here: https://www.castelion.com/team https://www.castelion.com/team
      - hollerith 2y ago
        I don't understand why you are getting downvoted. Thanks for the info.
wmf 2y ago
The problem is that most of your orbital assets will be in the wrong place when the conflict kicks off. Just look at a map of Starlink and observe how many satellites are nowhere near Russia/China. You'd have to launch a ridiculous number of satellites which would never be used. I also don't understand why intercepting faster is worth anything.
- throw9474 2y ago
  If the interceptors can also function at midcourse then it's not just the ones over Russia that participate. If you look at Starlink orbits, every single satellite in the constellation goes over any given point on Earth (e.g. Moscow) within a 12 hour period. So if the conflict lasts that long, the whole constellation can be unloaded.

hollerith 2y ago

The sentence I am criticizing is not about interception of ICBMs, so your link is not relevant. In particular, when the goal is to intercept an ICBM, the enemy helpfully raises the target to be (briefly) at the same altitude as the satellite. (An ICBM's max altitude is much higher than low-earth orbit.) If the goal is for a satellite to attack a city, the enemy does not helpfully raise the city to orbital altitudes.

throw9474 2y ago
I think the idea is in an arms race, if you can't launch ICBM nukes anymore (because of Musk's orbital interceptors) then you have to pre-launch nukes into orbit. THOSE nukes can then strike faster than ICBMs (just like interceptors can).
- hollerith 2y ago
  I understood the we were talking about "pre-launching" nukes into orbit. I also understand that those nukes regularly get deliciously close to their targets (100 miles or so) (delicious from the point of view of the attacker). I stand by my assertion however: to be explicit, for the same energy budget, it is quicker to hit a target from the ground half-way around the world from the target than it is to hit the target from orbit even if the satellite is directly above the target. The exception to that is laser weapons because a laser beam has no momentum whereas all the "strategic" nukes in the US arsenal weigh at least 200 lb, which is a lot of momentum when moving at orbital speed. (Also, it is vastly cheaper to maintain infrastructure on the ground than in orbit.)
  - georgeg23 2y ago
    The satellite can deploy a hypersonic glide vehicle and utilize it's orbital velocity to manueve within the atmosphere. See Fractional Orbital Bombardment. China tested theirs last year. ...SpaceX people are building it here: https://www.castelion.com/team https://www.castelion.com/team
    - hollerith 2y ago
      I don't understand why you are getting downvoted. Thanks for the info.

wmf 2y ago

The problem is that most of your orbital assets will be in the wrong place when the conflict kicks off. Just look at a map of Starlink and observe how many satellites are nowhere near Russia/China. You'd have to launch a ridiculous number of satellites which would never be used. I also don't understand why intercepting faster is worth anything.

throw9474 2y ago
If the interceptors can also function at midcourse then it's not just the ones over Russia that participate. If you look at Starlink orbits, every single satellite in the constellation goes over any given point on Earth (e.g. Moscow) within a 12 hour period. So if the conflict lasts that long, the whole constellation can be unloaded.