4 ms·

I think as far as operational capabilities go, all BPI stuff is just not there (at least from public info) and at best, starlink would only be good a large scal

I think as far as operational capabilities go, all BPI stuff is just not there (at least from public info) and at best, starlink would only be good a large scale detection, target aquisition and tracking: [0]"While boost-phase defense has been advocated as the most efficient way to deal with fractionated payloads and exoatmospheric (midcourse) penetration aids, it is extremely sensitive to assumptions about threat booster characteristics. Over time, boost-phase defense tends to be renamed ascent-phase defense when the kinematic realities set in. In fact, ascent-phase defense is code for engagement in the postboost or early midcourse phases of flight. The limitations and complications of a surface-based boost-phase defense lie primarily in the concepts of operations (CONOPS), policy, time, and geography. Since the timelines for engagement in the boost-phase are extremely short, the on-site commander must have authorization from the National Command Authority to launch an interceptor immediately after a threat missile has been detected.1 Also, access must be gained to countries adjacent to the threat country in order to position a boost-phase system close enough, and at the correct geometries, to successfully engage the threat missile. Finally, boost-phase systems are only effective against countries that do not have large enough landmasses to allow them to launch missiles from deep within their territory. The airborne laser is designed to deliver energy at the speed of light to perform the boost-phase intercept mission. Space-based lasers were also pursued in the past. Virtually no fly-out time is involved, and the beam agility is a function only of how fast the pointing optics can be repositioned. While laser weapons sound like the obvious answer, the energy that a laser can deliver on a target is limited by the power available and the aperture of the device. Atmospheric effects disturb the beam. Much has been accomplished in advancing the pointing and tracking capabilities and the adaptive optics to maintain beam quality, but some fundamental limitations remain." [0] https://nap.nationalacademies.org/read/13189/chapter/4 https://nap.nationalacademies.org/read/13189/chapter/4

WalterBright 4y ago
I read in the Scientific American that a defense against lasers would be simply spinning the target, which would require the attack laser to have much more power. The target can be made shiny, and can be coated with an ablative material.
- cinquemb 4y ago
  Yeah, I'd factor that into major limitations with the space based laser systems. Only think I can think of that could work around that is if one used an array of lasers that could constructively interfere during boost phase that could cause some kind of major turbulence at the point of intersection (maybe along the lines of the laser collisions here[0]: "Fülöp and colleagues argue that the energy problem could be overcome by splitting the laser pulse into two equal-energy pulses, which then hit the target simultaneously at different, precisely calculated angles of incidence (see figure). Through simulations, the team showed that when the laser pulses collide, a standing wave forms inside the solid target that increases the peak electric field. With the same pulse intensity used in previous experiments, their calculations suggest that the technique can double the energy of the proton beam and produce five times as many protons — all with far more flexible control parameters than required before."). [0] https://physicsworld.com/a/laser-collisions-could-boost-proton-beam-energies/ https://physicsworld.com/a/laser-collisions-could-boost-prot...
robonerd 4y ago
The part of this document that you're quoting is talking about the limitations of land/sea based boost-phase interceptors. Scroll down to the Space-Based Interceptors section. I don't think there's much substance here.. It talks about kill vehicle size (see: LEAP), and mentions that coverage depends on the number of interceptors and the inclination of their orbits (no kidding.)
- cinquemb 4y ago
  The section i quote referrers to space based lasers too. I also haven't see anywhere publicly on any actual space based kinetic system even in testing for BPI usuage (which would still face the same kinematic issues with land and sea based system).

WalterBright 4y ago

I read in the Scientific American that a defense against lasers would be simply spinning the target, which would require the attack laser to have much more power. The target can be made shiny, and can be coated with an ablative material.

cinquemb 4y ago
Yeah, I'd factor that into major limitations with the space based laser systems. Only think I can think of that could work around that is if one used an array of lasers that could constructively interfere during boost phase that could cause some kind of major turbulence at the point of intersection (maybe along the lines of the laser collisions here[0]: "Fülöp and colleagues argue that the energy problem could be overcome by splitting the laser pulse into two equal-energy pulses, which then hit the target simultaneously at different, precisely calculated angles of incidence (see figure). Through simulations, the team showed that when the laser pulses collide, a standing wave forms inside the solid target that increases the peak electric field. With the same pulse intensity used in previous experiments, their calculations suggest that the technique can double the energy of the proton beam and produce five times as many protons — all with far more flexible control parameters than required before."). [0] https://physicsworld.com/a/laser-collisions-could-boost-proton-beam-energies/ https://physicsworld.com/a/laser-collisions-could-boost-prot...

robonerd 4y ago

The part of this document that you're quoting is talking about the limitations of land/sea based boost-phase interceptors. Scroll down to the Space-Based Interceptors section. I don't think there's much substance here.. It talks about kill vehicle size (see: LEAP), and mentions that coverage depends on the number of interceptors and the inclination of their orbits (no kidding.)

cinquemb 4y ago
The section i quote referrers to space based lasers too. I also haven't see anywhere publicly on any actual space based kinetic system even in testing for BPI usuage (which would still face the same kinematic issues with land and sea based system).