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> Fighter jets use missiles, not flak. Do you think the missiles go and touch the opposing fighter jet? Hit-to-kill systems exist, but most missiles maneuver,

by mlyle 4y ago

> Fighter jets use missiles, not flak. Do you think the missiles go and touch the opposing fighter jet? Hit-to-kill systems exist, but most missiles maneuver, get as much of an intersecting path as they can, and then explode to kill the target with fragments. > At the point you're getting close enough to make a hit probable you're already most of the way towards a direct strike anyway. Here, you don't select for the highest probability of kill on a certain pass, but instead the highest probability of damage integrated over many orbits. You also don't select for the highest probability of killing a given SV, but of killing satellites in a given constellation with closely related orbits.

JumpCrisscross 4y ago
> maneuver, get as much of an intersecting path as they can, and then explode. Which is the "getting close enough to make a hit probable" I described. > don't select for the highest probability of killing a given SV, but of killing satellites in a given constellation with closely related orbits I get the hypothesis. But if you run the orbital math, interaction is vanishingly unlikely. Kessler syndrome is triggered by massive orbital objects breaking up and creating a domino effect at high altitudes, where orbital decay is minimal on human timeframes. Kessler concerns were raised with respect to Starlink, but I haven't seen anyone balance the math for massive numbers of small objects. Even for the classic case, when you actually run simulations, most objects don't interact.
- mlyle 4y ago
  > But if you run the orbital math, interaction is vanishingly unlikely. E.g. a Falcon 9 can put 14 tonnes into a higher LEO. Assume you fill it 90% with 1cm diameter tungsten spheres, and the rest with an optimized dispersal system. That's 1.26 million spheres slowly decaying through your target orbit, and you can end up with a favorable initial phase, altitude, and inclination. You'd be tripling the amount of debris of that scale in orbit in one launch, in a way that's disproportionately targeted at a specific constellation. (Probably 1cm diam is still excessively large. Also, when we talk about the original idea, you could have many smaller, even more optimized shots at individual spacecraft in the constellation).
  - deleted 4y ago
    [deleted]
  - JumpCrisscross 4y ago
    > 1.26 million spheres slowly decaying through your target orbit, and you can end up with a favorable initial phase, altitude, and inclination Three degrees of freedom are deceiving. Millions of projectiles sounds like a lot. It’s not. You could do this hundreds of thousands of times in LEO and thousands in MEO and still barely change a single satellite’s collision odds.
    - mlyle 4y ago
      Satellites die from collisions today. > You could do this hundreds of thousands of times in LEO and thousands in MEO and still barely change a single satellite’s collision odds. I have to think that multiplying the number of debris objects by 300,000 for a few months *, and preferentially targeting that debris at a specific satellite would change its odds a bit. So, you're way off in hyperbole-land at this point. Of course, it all depends on what we mean by "targeting". Still, one launch gets you approximately 3x the total amount of debris in orbit, and the opportunity to choose how it's distributed. * Objects with a mass/surface area ratio of ~15 kg/m^2 decay in about a year in LEO, depending upon space weather and other factors. The tungsten balls have a ratio of 32 kg/m^2, so can be expected to last a fair bit longer.
    - Teever 4y ago
      Something doesn't jive here. If a million projectiles in one orbit isnt something to worry about then why are we worried about Kessler Syndrome with the thousands of satellites and junk that is already up there?
      - JumpCrisscross 4y ago
        > why are we worried about Kessler Syndrome with the thousands of satellites and junk that is already up there? One, Kessler syndrome should really be called the Kessler hypothesis since we’ve never actually proven it’s a problem in any real form. To the degree it’s been rigorously modelled, it would create a lot of property destruction in a limited number of orbital planes, not block access to space. The problem is breaking stuff. Not blocking. Two, where it’s been rigorously modelled and shown to be a problem (again, only for a limited set of planes) it derives from something big breaking apart. Not lots of small stuff. And again, we’re talking about a bunch of property destruction. Not annihilation of everything in the plane let alone orbit.

by mlyle 4y ago

JumpCrisscross 4y ago

> maneuver, get as much of an intersecting path as they can, and then explode. Which is the "getting close enough to make a hit probable" I described. > don't select for the highest probability of killing a given SV, but of killing satellites in a given constellation with closely related orbits I get the hypothesis. But if you run the orbital math, interaction is vanishingly unlikely. Kessler syndrome is triggered by massive orbital objects breaking up and creating a domino effect at high altitudes, where orbital decay is minimal on human timeframes. Kessler concerns were raised with respect to Starlink, but I haven't seen anyone balance the math for massive numbers of small objects. Even for the classic case, when you actually run simulations, most objects don't interact.

mlyle 4y ago
> But if you run the orbital math, interaction is vanishingly unlikely. E.g. a Falcon 9 can put 14 tonnes into a higher LEO. Assume you fill it 90% with 1cm diameter tungsten spheres, and the rest with an optimized dispersal system. That's 1.26 million spheres slowly decaying through your target orbit, and you can end up with a favorable initial phase, altitude, and inclination. You'd be tripling the amount of debris of that scale in orbit in one launch, in a way that's disproportionately targeted at a specific constellation. (Probably 1cm diam is still excessively large. Also, when we talk about the original idea, you could have many smaller, even more optimized shots at individual spacecraft in the constellation).
- deleted 4y ago
  [deleted]
- JumpCrisscross 4y ago
  > 1.26 million spheres slowly decaying through your target orbit, and you can end up with a favorable initial phase, altitude, and inclination Three degrees of freedom are deceiving. Millions of projectiles sounds like a lot. It’s not. You could do this hundreds of thousands of times in LEO and thousands in MEO and still barely change a single satellite’s collision odds.
  - mlyle 4y ago
    Satellites die from collisions today. > You could do this hundreds of thousands of times in LEO and thousands in MEO and still barely change a single satellite’s collision odds. I have to think that multiplying the number of debris objects by 300,000 for a few months *, and preferentially targeting that debris at a specific satellite would change its odds a bit. So, you're way off in hyperbole-land at this point. Of course, it all depends on what we mean by "targeting". Still, one launch gets you approximately 3x the total amount of debris in orbit, and the opportunity to choose how it's distributed. * Objects with a mass/surface area ratio of ~15 kg/m^2 decay in about a year in LEO, depending upon space weather and other factors. The tungsten balls have a ratio of 32 kg/m^2, so can be expected to last a fair bit longer.
  - Teever 4y ago
    Something doesn't jive here. If a million projectiles in one orbit isnt something to worry about then why are we worried about Kessler Syndrome with the thousands of satellites and junk that is already up there?
    - JumpCrisscross 4y ago
      > why are we worried about Kessler Syndrome with the thousands of satellites and junk that is already up there? One, Kessler syndrome should really be called the Kessler hypothesis since we’ve never actually proven it’s a problem in any real form. To the degree it’s been rigorously modelled, it would create a lot of property destruction in a limited number of orbital planes, not block access to space. The problem is breaking stuff. Not blocking. Two, where it’s been rigorously modelled and shown to be a problem (again, only for a limited set of planes) it derives from something big breaking apart. Not lots of small stuff. And again, we’re talking about a bunch of property destruction. Not annihilation of everything in the plane let alone orbit.