tag:blogger.com,1999:blog-8150340806781551727.post2125636097418050417..comments2024-03-28T10:39:31.521+00:00Comments on ToughSF: Lasers, Mirrors and Star Pyramids Matter Beamhttp://www.blogger.com/profile/16721504049578296529noreply@blogger.comBlogger69125tag:blogger.com,1999:blog-8150340806781551727.post-54899106918673279322023-03-26T17:53:05.414+01:002023-03-26T17:53:05.414+01:00That makes sense, thanks! That makes sense, thanks! Marco L.https://www.blogger.com/profile/09448730796569084980noreply@blogger.comtag:blogger.com,1999:blog-8150340806781551727.post-14915206851880696562023-03-26T17:50:36.029+01:002023-03-26T17:50:36.029+01:00Hi!
Inverse cones would indeed work, but they hav...Hi!<br /><br />Inverse cones would indeed work, but they have two disadvantages:<br />-Laser light bouncing off one slope would hit the opposite side instead of leaving into empty space<br />-Vaporized material from a site under laser attack would splatter onto the rest of the inverted cone's surfaces, which would degrade them from smooth and shiny into rough and absorbing. When those degrades surfaces then get attacked, they won't perform well. Matter Beamhttps://www.blogger.com/profile/16721504049578296529noreply@blogger.comtag:blogger.com,1999:blog-8150340806781551727.post-53929065709712412472023-03-26T02:28:20.481+01:002023-03-26T02:28:20.481+01:00Another thought: shaping armor with small peaks an...Another thought: shaping armor with small peaks and valleys to increase surface area at no mass cost?Marco L.https://www.blogger.com/profile/09448730796569084980noreply@blogger.comtag:blogger.com,1999:blog-8150340806781551727.post-64561236807469086092023-03-26T02:23:52.527+01:002023-03-26T02:23:52.527+01:00This comment has been removed by the author.Marco L.https://www.blogger.com/profile/09448730796569084980noreply@blogger.comtag:blogger.com,1999:blog-8150340806781551727.post-62786593482674838302022-12-25T09:57:23.635+00:002022-12-25T09:57:23.635+00:00Frank, with regard to your point about hiding the ...Frank, with regard to your point about hiding the mirror of the laser away when not in use, might you consider the concept of a laser generated safely inside the craft and then focused/fired using one or more mirrors which allow is to be shot in various directions away from the direction that the craft/generator is pointing? I remember seeing something of the sort on the Atomic Rockets website. Alexhttps://www.blogger.com/profile/05147204379922772600noreply@blogger.comtag:blogger.com,1999:blog-8150340806781551727.post-62279935238215757042021-12-01T23:22:11.955+00:002021-12-01T23:22:11.955+00:00You are welcome!You are welcome!Matter Beamhttps://www.blogger.com/profile/16721504049578296529noreply@blogger.comtag:blogger.com,1999:blog-8150340806781551727.post-76999664840204142662021-11-25T16:54:58.240+00:002021-11-25T16:54:58.240+00:00Thanks a lot for your hard work as always! Thanks a lot for your hard work as always! D.C.Elingtonhttps://www.blogger.com/profile/11698702122512660897noreply@blogger.comtag:blogger.com,1999:blog-8150340806781551727.post-50949806701214944742020-08-18T11:48:51.471+01:002020-08-18T11:48:51.471+01:00Great work. You have really put an huge effort to ...Great work. You have really put an huge effort to create this. If anyone wants to know basics before learning things feel free to read this https://laserund.blogspot.com/Math and physicshttps://www.blogger.com/profile/02623756363900439496noreply@blogger.comtag:blogger.com,1999:blog-8150340806781551727.post-38079021177629211152018-12-03T18:11:03.255+00:002018-12-03T18:11:03.255+00:00I think you made a minor error in your phrasing: t...I think you made a minor error in your phrasing: the James' Webb telescope is 6.5 meters wide. Thus, your 10 meter mirror is a little less than 2x as wide as the Jame's Webb telescope, while your phrasing seems to suggest the 10 meter mirror is half as large as the Jame's Webb.<br /><br />"The focusing mirror is 10 meters wide, about half as wide as the one the James Webb telescope uses."<br /><br />This I think, if it isn't simply misstated, or if not confuses how big a 10 meter mirror is: the Jame's Webb mirror has an area of about 25 m^2, while a 10 meter mirror has an area of about 75 meters, nearly 3x as large.<br /><br />Thus, your looking at a 15 ton or so focusing element of a 10 meter alone.<br /><br />Anonymousnoreply@blogger.comtag:blogger.com,1999:blog-8150340806781551727.post-50649552255678596722018-08-13T12:53:06.771+01:002018-08-13T12:53:06.771+01:00This comment has been removed by a blog administrator.Anonymousnoreply@blogger.comtag:blogger.com,1999:blog-8150340806781551727.post-53478138062233675592018-07-07T02:46:45.762+01:002018-07-07T02:46:45.762+01:00Agreed, pulsed lasers can be very damaging. Mirror...Agreed, pulsed lasers can be very damaging. Mirror armor only works at ranges where the laser is not intense enough to heat up the armor to the point where it melts or vaporizes. All the tricks and techniques mentioned here, from mirrors to active cooling and sloping, are meant to extend that range.<br /><br />Pulsed lasers, with their ability to generate high intensities, will force the armored target to stay a long distance away to remain safe. <br /><br />If you take the heat resistance of the armor, and divide it by the peak intensity of a laser, you can work out the distance needed to stay safe.Matter Beamhttps://www.blogger.com/profile/16721504049578296529noreply@blogger.comtag:blogger.com,1999:blog-8150340806781551727.post-34018245813776145922018-07-05T22:24:34.335+01:002018-07-05T22:24:34.335+01:00You should probably give more consideration to the...You should probably give more consideration to thermal stress. Powerful pulsed lasers can blow out chunks of solid material along with the vapor.Andrew Broekerhttps://www.blogger.com/profile/03455959935160897929noreply@blogger.comtag:blogger.com,1999:blog-8150340806781551727.post-58500759535677671622018-06-10T22:22:53.391+01:002018-06-10T22:22:53.391+01:00Modern dielectric mirrors have been proven to refl...Modern dielectric mirrors have been proven to reflect wavelengths as short as 193nm very effectively (98% https://www.newport.com/f/long-lived-deep-uv-excimer-mirrors), so by 'short', you must mean soft X-rays and shorter (10nm and below). Matter Beamhttps://www.blogger.com/profile/16721504049578296529noreply@blogger.comtag:blogger.com,1999:blog-8150340806781551727.post-23193784020442074632018-06-10T13:10:40.163+01:002018-06-10T13:10:40.163+01:00Thanks, this justifies the uses of short wavelengt...Thanks, this justifies the uses of short wavelength lasers.Anonymousnoreply@blogger.comtag:blogger.com,1999:blog-8150340806781551727.post-9269894357319838752018-06-05T18:03:03.065+01:002018-06-05T18:03:03.065+01:00I have had problems with notifications recently to...I have had problems with notifications recently too - the solution, it seems, is to click on the 'notify me' box at the bottom of the reply section.<br /><br />A Casaba Howitzer would make a missile massively more effective. It doesn't have to directly hit the target, so tracking its movements and matching them becomes much easier. Even more importantly, the target cannot afford to rely on Whipple shields and interceptor drones. They will be forced to launch anti-missile missiles and use powerful lasers, which is much more mass and energy intensive.<br /><br />Overall, Casaba Howitzers level the playing field between attacker and defender when using projectiles with a high relative velocity. <br /><br />Note that the temperature and Isp I used for the Maser-Water rocket is just an example. The actual temperatures you can reach depend mostly on how tightly you can focus the beam into the reaction chamber and/or how much energy each laser pulse contains. Laboratory tests regularly push metals and plastics to temperatures as high as 1,000,000K. That would translate into an Isp increase of 10x over the 10,000K example. However, there are diminishing returns. You'd end up reducing the projectile mass by a few kg while increasing the 'burn track' by thousands of kilometers...<br /><br />A chemical missile shouldn't be used as a 'torpedo'. You should capitalize on the fact that it is the cheapest propulsion option and you can fire you entire ammunition load at once. The best way to use them is therefore in massive, single waves of hundreds if not thousands of projectiles. They become even better if you build up a bit of relative velocity with the launching spaceship.<br /><br />De-orbiting projectiles for orbital bombardment is a bit of a special case. You only really need to deliver about 100m/s in LEO to lower the projectile's periapsis enough for it to get caught in the atmosphere and dragged down. On an airless body, you'd need to spend more deltaV but it is still just a small fraction of the orbital velocity. <br /><br />I agree with the rest of your points. Matter Beamhttps://www.blogger.com/profile/16721504049578296529noreply@blogger.comtag:blogger.com,1999:blog-8150340806781551727.post-5249604993584592052018-06-04T20:46:52.271+01:002018-06-04T20:46:52.271+01:00Edit: I just noticed that the article I was referr...Edit: I just noticed that the article I was referring to was actually written by you. How embarrassing for me to not spot that earlier. Frank_Groundzerohttps://www.blogger.com/profile/05201777694086621102noreply@blogger.comtag:blogger.com,1999:blog-8150340806781551727.post-30164144508204703112018-06-04T20:34:58.784+01:002018-06-04T20:34:58.784+01:00Sorry for the late reply, notifications have been ...Sorry for the late reply, notifications have been a little erratic<br /><br />Thank you a lot for all the efforts you've put in this last answer. <br />If my conversion is correct, a maser thermal booster will require arround 4.6 cubic meters of pure water to propel a ton of warhead. if I put that in perspective, the missile will be realative small compared to the ship launching it, but still has the potential of wrecking hostile warships if armed correctly. A ton of warhead is, if i remember correctly, the same weight of a large casaba howitzer bolt study that I found back on Atomick Rockets. I don't know if a Casaba Howitzer would increase the lethal range of such a missile by much, but we may spare a few Km of flight and, thus, achieve a better chance of successfully hit the tyarget. Now, on the same study, a small casaba howitzer bolt would be 50 Kg or so; if we maintain the mass ratio, it would require only 230 Kg of water (my calculations could be off, however), which transaltes in some 0.23 cubic meters. This is a very small missile, but may be able to deliver one hell of a punch to anything. The smaller the missile, the more a ship could be able to carry; and if we add the ability to such missiles to be "fired" in volleys, maybe 10 to 20 missiles per volley, it could make a very interesting weapon system.<br />Yet, I must point out, my reasoning and calculations may be flawed.<br /><br />The three missile types you propose do open up a series of scenario that may be plausible (in my mind). For example, the chemical missile could be used as a torpedo of sorts (slower acceleration than a warship, but capable of crippling damage) which could even be the final stage of another weapon; it could also work as a guided bomb of sorts, "dropped" by a warship orbiting a planet, deorbited with the chemical engine and pointend against a surface target, guided by something like a MARV. The Nuclear missile is something akin to an anti-ship cruise missile, gets fired from a very long distance, but is still very fast; the fact that the drive module could be detached and reused adds benefits to the cost of such a weapon (and de fact that it would be carried in minimal numbers). The Beam-propelled missiles could be used in various scenarios, maybe even self defence; I would probably equip them with Casaba Howitzer bolts, to maximize damage potential. <br />This are some of the idea that I have based upon what you said are likely.<br /><br />Sorry for the long answer and, again, thanks a lot!<br />Frank_Groundzerohttps://www.blogger.com/profile/05201777694086621102noreply@blogger.comtag:blogger.com,1999:blog-8150340806781551727.post-21312247281388836252018-06-04T11:50:35.126+01:002018-06-04T11:50:35.126+01:00Huge mirrors in space have always fascinated me. T...Huge mirrors in space have always fascinated me. Thanks for pointing those ones out!<br /><br />If anything, they can give us an idea of how much huge optics in space are supposed to weigh. Matter Beamhttps://www.blogger.com/profile/16721504049578296529noreply@blogger.comtag:blogger.com,1999:blog-8150340806781551727.post-75680860629550296502018-06-04T11:49:20.275+01:002018-06-04T11:49:20.275+01:00Rolling doesn't consume reaction mass, and I h...Rolling doesn't consume reaction mass, and I have come to believe that the optimal motion of a cone of armor is a wild wobble: both vertical and horizontal rotation! This can spread the beam over a maximum surface area.<br /><br />The jinking only has to cover the distance of the beam width or the projectile, whichever is smaller. If it is burning on the left (creating a force towards the right), you spend a tiny amount of maneuvering propellant to move the beam onto the right, to create a force towards the left that cancels out the previous force.<br /><br />If the projectile is, say, 10cm wide and 10kg, you'd only need 1.36kg of 350s Isp propellant accelerating at 0.1m/s^2 to maintain a perfect dodge for an hour. <br /><br />I think this is proposing that wobbling needles are better than SCoDs. <br /><br />For one, the Electronic Warfare aspect was never considered when developing SCoDs. Small sensors with very narrow openings to look through are easily confused, and if they are guided from the launcher by a larger sensor and computer module, then you have a predictable signal to start jamming or interfering with...Matter Beamhttps://www.blogger.com/profile/16721504049578296529noreply@blogger.comtag:blogger.com,1999:blog-8150340806781551727.post-69265725508920568672018-06-04T08:45:11.697+01:002018-06-04T08:45:11.697+01:00Excellent post. JWST is huge for sure, but also lo...Excellent post. JWST is huge for sure, but also look up ATLAST and RAMST.Anonymousnoreply@blogger.comtag:blogger.com,1999:blog-8150340806781551727.post-70883905285153087842018-06-03T04:14:49.627+01:002018-06-03T04:14:49.627+01:00And here we see the process of diminishing returns...And here we see the process of diminishing returns. The missile either runs out of reaction mass to jink or roll, and drifts harmlessly away, or it must be built larger to hold more fuel, making it a larger target, meaning it needs to do more evasive manoeuvres, etc.<br /><br />In this sort of scenario, I find the Soda Cans of Death (SCoD) idea more convincing, since once they are on the way, they are almost sacrificial. All they need is a very small motor to do terminal manoeuvres if they are close enough, and if one is shot down, there are still several thousand to go. Even at close range, the molten pieces of the SCoD barrage is still full of kinetic energy, and likely to cause damage to you or some following ship in the constellation (or maybe rain down on the planet or asteroid "below").<br /><br />I suspect this sort of calculus is already being worked on right here and now, as the US military begins to formalize the "Third offset" and introduces swarms of cooperative robotic vehicles on land, sea and air to overwhelm increasingly effective defences and AA/AD (Anti-Access/Area Denial) systems opposing the entry of American and Coalition forces.Thucydideshttps://www.blogger.com/profile/09828932214842106266noreply@blogger.comtag:blogger.com,1999:blog-8150340806781551727.post-70254906254829283552018-06-01T13:40:01.925+01:002018-06-01T13:40:01.925+01:00The longest X-ray wavelengths, called 'soft X-...The longest X-ray wavelengths, called 'soft X-rays' can be reflected with difficulty by some very large, heavy and specialized mirrors. <br /><br />The X-rays that nuclear warheads and XFELS produce are hard X-rays, and pass through everything or are absorbed, with no reflection. Matter Beamhttps://www.blogger.com/profile/16721504049578296529noreply@blogger.comtag:blogger.com,1999:blog-8150340806781551727.post-89256068515402250142018-06-01T13:38:45.638+01:002018-06-01T13:38:45.638+01:00Well, we can ignore ionized air for space projecti...Well, we can ignore ionized air for space projectile, but here's a working out for ablative lasers:<br /><br />Take the laser output in watts, and divide it by the vaporization energy of the missile's armor.<br /><br />For example, if you have a 100MW laser and the missile is covered by graphite that takes 62MJ/kg to vaporize, then the laser is vaporizing 1.62kg/s. <br /><br />Graphite vaporizes at 4000K. Using a Root Mean Square gas velocity calculator (http://calistry.org/calculate/kineticTheoryVelocityCalculator), we can work out that vaporized carbon expands at a velocity of 2883m/s.<br /><br />With a mass rate and a velocity, we can calculate a thrust. 1.62*2883: 4650N. <br /><br />A laser shining on a flat surface can create a flat nozzle with an efficiency of 50%. That means that 4650/2: 2325N of force is applied to the missile. <br /><br />If the laser spot is wider than the entire missile, then it will only be slowed down. If the laser spot is smaller than the missile, it will create more thrust on one side than the other, and start to push the missile sideways. <br /><br />It can be countered by rolling the missile and jinking to spread the beam. Matter Beamhttps://www.blogger.com/profile/16721504049578296529noreply@blogger.comtag:blogger.com,1999:blog-8150340806781551727.post-44094291153912216772018-06-01T13:32:57.886+01:002018-06-01T13:32:57.886+01:00The video cites energy absorbed per cubic meter, w...The video cites energy absorbed per cubic meter, which is not as important in space as energy absorbed per kilogram. <br />Using the numbers provided, and taking 2660kg/m^3 as the density of magnesium sulphate, I work out a thermochemical energy storage density of 1.05MJ/kg. That's good, but far below the 60MJ/kg of hydrogen.<br /><br />And, that storage happens at a transition temperature of 120°C, which is not very stealthy!Matter Beamhttps://www.blogger.com/profile/16721504049578296529noreply@blogger.comtag:blogger.com,1999:blog-8150340806781551727.post-76392678486082488182018-06-01T13:28:01.575+01:002018-06-01T13:28:01.575+01:00Impedance might be a issue, but it beats being com...Impedance might be a issue, but it beats being completely blind. <br />If the layer of laser armor is graphite with water cooling and maybe a reflective layer of aluminium on top, then it will not prove a problem for meter-long wavelengths that Radar uses. <br /><br />Lasers would reflect off the aluminium layer or ablate the graphite layer, but would not reach the radio emitter until all the armor has been excavated. <br /><br />Interstellar warfare is a whole other ball game, that's for sure. Once you have terawatt lasers sitting around, warfare would be transformed, but it is a big assumption to add those sorts of energies to any setting without proper justification and an extended timeline. Matter Beamhttps://www.blogger.com/profile/16721504049578296529noreply@blogger.com