Spacescifi

Orion will always be more energetic than a rocket, so it is more efficient at being a torchship. And Orions still matter here. Laser induced fusion via portal means you no longer need a fission trigger. No more bombs needed. Just fuel you can zap into fusion blasts to push you along.

Thanks. Before you posted the latest, I had begun to suspect what you confirmed... the inverse square law tends to be inverted when it comes to high energy. Want to handle a high flow rate for a super energetic rocket? You must build it bigger. Much bigger. The engine and the nozzle and everything really. The bigger your ship is the more heat you can take and thus the more powerful engine you can use. But yeah... you just confirmed doing the NIF laser continously is virtually impossible.... though one could do it in theory using sufficient dams and water power if you could convert (hard part) much of it into laser zapping. Conclusion: Any honest to goodness torchship would be massive by necessity. And the classic starships that warp from system to system? Assuming they are not drawing there power from 'beyond' then they would have to be much larger still That pic you showed me would be nothing compared to the size of an FTL jump/warp ship dependent on it's own power only. More practical sizes can be had by just learning to love the pusher plate orion... the classic torch drive is just less efficient the more energetic it becomes, whereas the Orion becomes more efficient until you also have to scale it up to not melt it. So Orions really do beat torchships for efficiency, especially when you are forced to scale up or else. A torchship with equal delta v and thryst to an Orion would likely be larger abd heavier still. So Orions, in either nuclear, pure fusion, AM or some other method have a more promising future ahead so far.... even though pop scifi is stuck on torchships like they are the best and only way. They are not. They are less efficient.

Too bad. Well if we could fire the NIF continously through the portal, I think 500 terawatts may be more than the engine can handle anyway without melting. Right? Sure I know propellant ejects the waste heat, but once the energy ejected is high enough the little energy the engine does absorb may be too much to handle. Kind of like the fictional 99% torch rocket whose 1% waste heat is so high it forces it to use massive radiator fins. I am not sure if 500 terawatts going off in the combustion chamber without destroying it is possible. You would probably need magnetics. And now we are back to fusion tech LOL.

What if we somehow managed to make the NIF laser fire continously through the portal? That is 500 terawatts (if I read correctly) of power going into the exhaust! How would that compare to NSWR? Still not good enough? How in the world do we make the NIF laser fire continously at 500 terawatts? Do we even know how... or is that just wishful scifi hope?

Understood... and thanks. Still not as good as Zubrin's NSWR? Or better? I will find out in a few days. The only real danger is nations weaponizing the portals.... which too easy with nukes on Earth. Survive a century... but then again if we did not... no fiction so Makes sense you need a saccherine start.

Actually I could solve cooling issue with regenerative cooling (coolant piped over portal) and likely ugly huge radiator fins. Sad how physics ruins our day and TWR with huge radiator fins unless you cheat with indestructable technology.

5 meter diameter aperture portal. Yes the portals are destructable (melting point of tungsten). The main problem I see is melting the portal in tge combustion chamber. How do we solve that? It will be near or surrounded by propellant right? The portal? It would ablate no? By the way... the portal ring weighs 3 tons. And if it is destroyed it goes off like a 3 ton AM bomb.

If you don't wish to play along fine. Just invented the scenario to see if we could cheat an NSWR using a contineous terawatt laser on propellant rocketry or not. A powerstation can give a spaceship more power than it would have normally. Waste heat is still an issue, just less so.

You could just engineer your PC to be a power hog anyway. You need a wrist wrap thing you can buy to ground yourself electromagnetically to manually install stuff on your motherboard without zapping it via static. Takes more work... possible though. You would be surprised what computers can do with sufficient programs and power. It's too often misused though.

I will answer with questions per your reply: 1. What is EM radiation? 2. What is a networked portal? Shine any radiation you wish through instantly no matter the distance. How many portals? Earth gets a billion divided evenly amomg the nations...because they teleport them straight in. Which means each nation gets 5128205 portal gates.

Disclaimer: This scenario is not for a fic I am writing. I am just using it to see if we can do it or not. Scenario: Aliens show up in 2020 and say: "We will give you these photon portals of ours as a test. Each portal has an aperture portal area of 5 meters. You will use them to estabilsh two occupied outpost colonies on other moons, asteroids, or planets in your solar system within a century of time. If you succeed you get to keep the WORKING photon portals. If you fail then when we return in a century, we will allow the portals to shut off. Just so you know, they are set to shut off a century from the moment you turn them on.... whether you turn it off or on matters not as far as affecting that after you turn it on. Just to be clear, when we arrive in a century both outposts must be occupied with your kind." Human Ambassador: "Can we have more time?" Alien Ambassador: "Where is your trust in your species? Surely your kind can do this in 100 of your years! We would not have offered the technology if we thought you could not. On the other hand... if you cannot or do not want to, then we will give the technology to some other kind that proves themselves worthy." "Can you show us how it works-the technology?" "No. We do not know. We were given the same test as you... or rather a series of tests. We lost at times but other times we won... and well, here we are." "You are saying you were given it for passing a test like what you are proposing to us? Who gave it to you?" "The Researchers of course!" "Who are they?" "They are like gods..... as we have no known science to explain the technology they have have given us. It's an experiment or hobby of theirs to do this. We work for them. And before you ask, none of us has seen one and returned to tell anyone about it. Some have entered their starships but no one has ever returned, so I suppose it is better not to try." Main question: Could we succeed at the test? Or is the alien ambassador just trolling us for laughs? Like they do not think we can do it and would be totally shocked if we managed to pull it off? My guess: I dunno, maybe we could find a way to fire the 500 terawatt NIF laser CONTINOUSLY down the portal to a portal linked spacex ship to give it deltav/thrust on par with or close to Zubrin's NSWR? Maybe better (would be nice)? Or is all this just hopeless? We get to play with portals for a century (and later for the spares we don't use but only a century as well for those). What are your ideas? Can we do it?

Benefits? 1. Mobile launch system . 2. Launch anywhere abilty. If a buyer needed that...beyond james bond villains LOL.

Read my EDIT please... I think this idea, new one could be a good one. I just think, water is like gold in space, and we have a gold mine, why not use it to get to space easier? Also makes return landings easier.

If I were trying to sell the idea and I were rich like Elon, the only ones that would want DIY repeat launch ability from the ocean with no infrastructure would be the airforce. It is simply too OP to jusify civillian use. A single booster can launch mulitple second stages suppied by an ocean carrier. Each time it launch, return to the earth and ress... That's it! Just make a two stage rocket launched from a carrier in the ocean. First stage lands in ocean. The ocean carrier cracks LH/LOX all day long and has plenty to spare. Fuels up first stage, attaches another second stage, launch again! That would be faster repeat launches than normal. At least until the carrier runs out of propellant and has to crack more.

Thanks for the information on nuclear. Clears things up concisely! Definitely this is real world consideratation of solutions. So guess the only good for nuclear is power, as it makes a lousy launch vehicle. Even the infamous metallic hydrogen or AM would do better.... assuming tge protective mass did not lower TWR badly. Perhaps their are other gases worth trying to make metastable other than hydrogen? As metals? Assuming it is possible with current at all.

The booster will carry the nuckear reactor solely for cracking LOX/LH from sea water. Chemical rocketry will propel it. The second stage is also chemical,but has a reserve nuclear reactor that can be used in orbit or for interplanetary where high thrust is not required but efficiency helps more.

There are ways to make an NTR not shoot out high levels of radiation. Yet from what I have seen, such measures often require reducing either mass flow, heat/energy, or both. I wonder if a non-nuclear two stage that cracks it's own LOX and LH from the ocean might be feasible instead?

There are two ways I am aware of that increase thrust. 1. Increase propellant flow or mass. 2. Increase exhaust speed. Number 1 has no limits if you don't mind staging to infinity. Number 2 is limited by heat/energy available and the engine's tolerance for it. I knew nuclear had better ISP, and I had assumed one could get thrust on par with chemical rockets if engineered sufficiently. Someone here mentioned nuclear dumbo rocket project that was aimed at doing that. LANTR is repeatedly mentioned as being capable of that as well. I have heard twice that nuke reactors are cooler than the SSME (spaces shuttle main engine) rockets. The main problem is not so much weight, but TWR. Nuclear TWR would need to be increased. So perhaps cracking LOX and LH is more practical. Perhaps just use a nuke reactor forthe cracking on earth, regular chemical for launch, and swtich to nuclear in space. Granted that would be a complex machine that could switch over it's main engine to NTR from chemical midflght.... but it could be done. Not cheaper than spacex, all it really grants is DIY way to orbit without any help but your own spaceship on Earth. That's is it's main advantagem

Wow... remind me that mathematicians and computers are the most essential crew you ever need on a scifi starship if getting NOT lost matters LOL. You or people like you should do just fine. Better than the starfleet.... regulars. Though I will admit it is hard for actors to truly demonstrate 'the right stuff' crews need to have when producers have an agenda and a budget that could care less.

Why on Earth? Who or what are you trying to learn or prove? Like in video games we push ourselves to fill our egos or take out aggression on inn-game enemies or simply to prove that we can beat the challenge and therefore can beat a similar or just as challenging if not more so one IRL also... after the game though. By the way.... no one here is going to tell you because if you or someone is hurt or worse we may get an opportunity to visit a courtroom. IP addresses human. They can find you and litigate you. Not even hackers are safe.... unless you have a bunch or 'burner' hardware that is not registered to you and fake addresses... but no legal, lawabiding citizen does that so...

So most regular commenters in this part of the forum will agree that two-stage rockets beat SSTO's at putting max payload or cargo in orbit. Whereas in scifi SSTO's tend to take precedence... it's a trope of sorts that is followed kind of without thinking about it Because of the success of Spacex, I thought of a new 2-stage rocket that could be more efficient... but also more expensive and risky. The Idea: A two-stage booster launched from the sea. First stage fills itself with water from the ocean, and uses nuclear reactor power plus airbreathing rocketry to accelerate the 2-stage up to a height where separation occurs and the second stage takes flight. The first stage falls back to the ocean but makes a powered landing with reserve water. To fly anywhere else to a waiting ocean carrier ship is as simple as water refueling, and then making more powered water landings if not close enough to the carrier to land. Beats flying over land where rapid refueling is not an easy option. This idea has obvious advantages, but it would be more expensive and risky than Starship. Also some have mentioned before that superheated steam tends to erode nuclear reactors.... which is not good. Surely there are engineering solutions that can be found, but my gut feeling is that the solution will be with technology we have yet to engineer. Something truly new. Your thoughts? To me it's like the wannabe child of Sea Dragon and Spacex.... with Zubrin as the godfather who both sides try to quiet whenever he begins to speak of uranium salts...

A casual google search reveals that average distance between stars is between 4-5 LY in the Milky Way, but is less toward the center. Do not go towar the center. No human life can live there because... radiation. Any human life would live in around the arm edges like us.

After playing Oolite (based on original elite with many add-ons), I wonder how well or not a 7 LY jump would work IRL? Some stars are farther than 7 LY, so in the game you hop from system to system, and some systems you cannot reach at all if there is no in between system to hop to. So how common are star systems that are farther away from other stars? 7 LY or further that cannot be jumped to. Because I am curious if the 7 LY jump can even work well at all, if most stars are closer than 7 LY together, then great, otherwise many places will be off limits.

Some have read about the infamous RBOD (Ravening Beam Of Death) from project rho (Winchell Chung's site). I just wanted to know what kind of power drain this would put on a spaceship if it had and fired one. Guesses: The more radiator fins the more it can zap. The less it has the less it can zap. Period. Does not matter what is powering it... whether nuclear reactor or antimatter. I have for sometime doubted the practicality of mounting a RBOD on a spaceship, due to the mass needed for cooling likely making the said spaceship slow as molasses. Meaning it will zap all day until it is ganked by clouds of projectiles, debris, and missiles it has no way of evading. Here us a 'quick' refresher: The ever useful Atomic Rockets site has a great section on laser weaponry, but the conclusion is far different than what you seem to be implying. Rather than have a multitude of laser weapons or optical systems, the ultimate aim is to create a Ravening Beam of Death (RBoD) and attack targets from as great a distance as possible. For practical reasons, this turns out to be one light second (just under the distance from the Earth to the Moon), since you can see the target, aim and make corrections in such a short time frame that the target cannot move an appreciable distance. The massive Free Electron Laser (or actually Xaser, since it is fired in the x-ray frequencies) near the end of the section can vaporize metal, ceramic and carbon in milliseconds at that range, and if you are on an unpowered orbit or on an asteroid, the beam is still lethal at a light minute and dangerous even a light hour away. Let's take a 10 MW ERC pumped FEL at just above the lead K-edge. This particular wavelength is used because lead is pretty much the heaviest non-radioactive element you can get, and at just above the highest core level absorption for a material you can get total external reflection at grazing angles - so no absorption or heating of a lead grazing incidence mirror. We will use a 1 meter diameter mirror. The Pb K-edge x-ray transition radiates at 1.4E-11 m. This gives us a divergence angle of 1.4E-11 radians. At 1 light second, we get a spot size of 5 mm, and an intensity of 5E11 W/m2. Looking at the NIST table of x-ray attenuation coefficients, and noting that 1.4E-11 m is a 88 keV photon, we find an attenuation coefficient of about 0.5 cm2/g for iron (we'll use this for steel), 0.15 cm2/g for graphite (we'll use this for high tech carbon materials) and 0.18 cm2/g for borosilicate glass (a very rough approximation for ceramics). Since graphite has a density of 1.7 g/cm3, we get a 1/e falloff distance (attenuation length) of 4 cm. Iron, with a density of 7.9 g/cm3, has an attenuation length of 0.25 cm. Glass, density 2.2 g/cm3, has an attenuation length of 2.5 cm. At 1 light second, therefore, the beam is depositing 2E12 W/cm3 in iron at the surface and 7E11 W/cm3 at 0.25 cm depth; 1.2E11 W/cm3 in graphite at the surface and 5E10 W/cm3 at 4 cm depth; and 2E11 W/cm3 in glass at the surface and 7E10 W/cm3 at 2.5 cm depth. Using 6E4 J/cm3 to vaporize iron initially at 300 K, we find that iron flashes to vapor within a microsecond to a depth of 0.9 cm. The glass, assumed to take 4.5E4 J/cm3 to vaporize (roughly appropriate for quartz) will flash to vapor within a microsecond to a depth of 4 cm within a microsecond. Graphite, at 1E5 J/cm3 for vaporization, will flash to vapor to a depth of 0.7 cm within a microsecond (the laser performs better if we let it dwell on graphite for a bit longer, we get a vaporization depth of 10 cm after ten microseconds). Net conclusion - ravening death beam at one light second. Now lets look at one light minute. The beam is now 30 cm across. This is much deeper than the attenuation length in all cases, so we will just find the radiant intensity and the equilibrium black body temperature of that intensity. We have an area of 7E-2 m2, and an intensity of 1.4E8 W/m2. You need to reach 7000 K before the irradiated surface is radiating as much energy away as heat as it is receiving as coherent x-rays. The boiling point of iron is 3023 K, the boiling point of quartz is 2503 K, and the sublimation temperature of graphite is 3640 K. All of these will be vaporized long before they stop gaining heat. At this range, the iron is subject to 5.6E8 W/cm3 at the surface, the graphite to 3.3E7 W/cm3 at the surface, and the glass to 5.6E7 W/cm3 at the surface. Using the above values for energy of vaporization, we get about 0.1 milliseconds before the iron starts to vaporize, 0.8 milliseconds before the glass starts to vaporize, and 3 milliseconds before the graphite begins to vaporize (because of its long attenuation length, once it begins to sublimate, graphite sublimates rapidly to a deep depth, while you essentially have to remove the iron layer by layer). Net conclusion - still a ravening death beam at one light minute. What about at one light hour? The beam is 18 meters across. The equilibrium black body temperature is 900 K. This is well below the melting point of most structural materials. Ten megawatts, however, is a lot of ionizing radiation. Any unhardened vehicle will be radiation killed at these ranges. Obviously, the ideas of "close, medium and far" ranges have very different meanings in a space war context. The only way to effectively deal with a weapon like that is to have several weapons of similar power in your constellation, or be prepared to fill the sky with tens of thousands of kinetic kill vehicles (referred to in Rocketpunk Manifesto as Soda Cans of Death or SCoDs). With an overwhelming number of targets, the individual laser will eventually not be able to track and kill every target, and of course other factors like the service cycle (how often you might have to stop and cool down the system), or the speed the laser mirror can swivel to track incoming targets reduces the absolute number of targets you can service even with a RBoD. Your thoughts?

When I still had dreams (never do anymore) I did not have a smart phone nor did I use one nor did I have a PC. I have dreamed of going to the old arcade rooms, but the dreams always lead to some action movie adventure... with me nearly almost always dying except for me having the power to end the dream right before that happens. I have been shot at, nearly ran over, and choked. Out of them all only the choking bothered me, as I felt that. I have the power to stop dreams midway so bullets never ever hit me... I just end the dream and wake up. For some reason I am always conscious and aware that I am in a dream... I know it is not real. So generally speaking I have fun until things become too dangerous, or I am about to have fun and the dream stops without me wanting it to. I never have had much in the way of superpowers in my dreams ever. Except as a young child I flew once... probably inspired from watching superman. After that my only power was the abiity to stop dreams outright... besides being strong enough (never superhuman though) to usually defeat or at least go toe to toe with whatever monster or human enemy confronted me. With my bare hands. That's how I survived the choking during a dream. A winged creature choked me but instead of shutting off the dream as per the usual I choked him back till it faded away and disappeared..