Both fission and fusion appear promising for space propulsion applications, generating higher mission velocities with less reaction mass. This is due to the much higher energy density of nuclear reactions: some 7 orders of magnitude (10,000,000 times) more energetic than the chemical reactions which power the current generation of rockets.
Very briefly Getting to space requires that the payload reach orbital or escape velocity. Maximum energy over a short period of time. This challenge has been met today by the various chemical rocket motors out there.
If you haven't already, I suggest checking out this website thouroughly: http://www.projectrho.com/public_html/rocket/index.phpIt has a lot of information on the basics of space travel and the not-so-basics of space travel with advanced propulsion systems.However, if you REALLY want a good intuitive understanding of space travel and orbital mechanics, I suggest buying and installing Kerbal Space Program. It'll let you build rockets and control them yourself to get som hands on experience, while providing lots of entertainment and explosions along the way. It makes some simplyfying approximations and strongly overestimates hardware reliabillity, but the physics are accurate and you'll learn a lot from it. You can buy it on their website or on steam.It's mostly focused on chemical propulsion with the only exceptions being an Ion engine and a NERVA-like Nuclear thermal engine, but there are mods to add in more speculative types of engines if you'd like. However, I strongly suggest playing with the stock game parts to begin with, as too powerful parts might ruin the gameplay to some extent as they can make the game too easy.
One of the main problems with getting up into space other than cost problem is fuel!! Getting in space 90% to 95% of the rocket is just fuel to get that small 5% payload up there, current rockets are multi-stage clamber to reach orbit. The fuel packs just enough of a punch to make the trip at all!!!!!! It uses fuel like drunken sailor!!!!!I was saying they need to research other fuel sources that is more fuel efficient.Some people where saying that may not be possible because of limitations imposed by chemistry on rockets.
CHEMICAL fuels, where energy is stored at the bonds BETWEEN ATOMS AND MOLECULES which are at their limit before becoming unstable.
The problem with chemical rockets is they have very low specific impulse around 400.That means they only operate for only a few minutes before all the fuel is gone.The highest specific impulse ever achieved for a chemical rocket was around 500 using Hydrogen ,Lithium and Fluorine.But was ridiculously hazardous and very challenging.And never will be used again because it is very hazardous and very dangerous.Trying to get chemical rockets to operate on higher specific impulse around 500 or 600 or higher is just too hazardous and very dangerous.It becomes too hot and wants to explode and thus you need new strong rocket material and think rocket.Well Ion engines and Plasma engines have very high specific impulse but very low thrust so would never take off from earth and bust be use in space only , not taking off from earth.Other option for even higher specific impulse are Fission rockets or fusion rockets that have a reactor to heat a gas and blast it out the back.But the rocket would probably explode because the thrust is too high.
I was not really asking how all these propulsion systems work.What I seem to be confused about is the laws of chemistry apposed on rockets.
.. grasp of even the most basic principals. You also have grammatical problems in your posts .. principals of chemical rocket propulsion, among others.
Well Ion engines and Plasma engines have very high specific impulse but very low thrust so would never take off from earth and bust be use in space only , not taking off from earth.Other option for even higher specific impulse are Fission rockets or fusion rockets that have a reactor to heat a gas and blast it out the back.But the rocket would probably explode because the thrust is too high.
Quote from: nec207 on 05/27/2014 04:52 amI was not really asking how all these propulsion systems work.What I seem to be confused about is the laws of chemistry apposed on rockets.I think the reason people are pointing you to information on the fundamentals of rocketry and physics is that you don't seem to have a grasp of even the most basic principles. You also have grammatical problems in your posts, and the result of all of that is that it's hard to even tell what you're talking about.For example, in the two sentences I quoted above, it's hard to tell what you mean. The first sentence seems to imply you are saying you understand the basic principles of chemical rocket propulsion, among others. The second sentence seems to be you saying you are confused by the laws of chemical rocket propulsion.
I did some reading today and don't know if I'm interpeding it right but saying generally been a trade-off between high thrust and high specific impulse. You can have one at the expense of the other, but not both. An exception would be nuclear pulse propulsion where exploding nuclear bombs behind the ship to propel it.So in way saying no you cannot have high thrust and high specific impulse it is normally one or the other not both.
The idea that improving launch rockets significantly beyond the state of the art would involve unacceptable hazards and difficulties only applies to chemical rocketry, because the reason for it is that the chemicals you'd need to use are dangerous.For example, using fluorine instead of oxygen in a hydrogen-fueled rocket could improve performance substantially, but fluorine is horribly poisonous and hard to handle, and the exhaust would be hydrofluoric acid instead of steam. Ozone would be good too; unfortunately it is also very poisonous, and it tends to decompose spontaneously (and exothermically) even at moderate concentrations in LOX. The problem is specifically the chemicals, not the heat and pressure they generate in the engine.This has nothing whatsoever to do with fission, fusion, airbreathing, or any other method that isn't a chemical rocket. Such methods have different problems, which are potentially surmountable.
I was saying they need to research other fuel sources that is more fuel efficient.Some people where saying that may not be possible because of limitations imposed by chemistry on rockets.
Quote from: nec207 on 05/27/2014 06:59 pmI did some reading today and don't know if I'm interpeding it right but saying generally been a trade-off between high thrust and high specific impulse. You can have one at the expense of the other, but not both. An exception would be nuclear pulse propulsion where exploding nuclear bombs behind the ship to propel it.So in way saying no you cannot have high thrust and high specific impulse it is normally one or the other not both.That is only true for some engines, like Ion engines. It is not true for chemical engines. Actually, AFAIK, it is actually the opposite for chemical engines, although it does not have so much impact as with Ion engines.
Ok,Simple answers.Chemical rockets have an upper limit as to how fast they can go with a given amount of fuel.Ion Rockets can go really fastwith very little fuel but don't put out a lot of thrust initially and take a LONG time to get up to speed. (Not powerful enough to lift of the planet.)The idea behind Fission and Fusion rockets is to get the fuel REALLY hot so it expands faster than the fuel from a chemical rocket would. The advantage here is that you can get a lot of thrust for a much smaller amount of fel than it would take for a chemical rocket, (Good for boosting to orbit), and once in space, it could give a big initial push and be throttled back for a continious thrust, similar to the Ion engine.Problem is, Fission engines require a nuclear reactor which will involve radioactive materials. An accident could contaminate a large area. And we haven't quite figured out Fusion Rockets or reactors yet, but there's been some very promising developments on this over the last year or so.Anti-matter could take a mass of anti-matter about the size of a quarter and slowly combine it with an equal amount of matter and produce enough thrust to go ANYWHERE in the solar system in a few weeks, under a continious thrust. Problem here, we still don't know how to make large quantities of anti-matter and haven't quite licked the problem of containing the antimatter for storage, let alone trickle it out as a fuel source.Hope this tells you what you wanted to know.
It's not complicated, there's only so much energy you can get out a chemical reaction.LOX/LH2 is almost as good as it gets, and the things that could theoretically give higher performance all have major drawbacks. There is really no chance of something dramatically better coming along.
Oh, there are much better things ! Who doesnt love their smell of perchloryl fluoride in the morning ?
To be just a bit blunt about it, the reason there is so much discussion about the non-existent (as of now) technologies mentioned by the OP is that people (myself included) desperately want the science fiction futures we've been reading about our whole lives to become realities right now.
Quote from: savuporo on 06/03/2014 06:48 amOh, there are much better things ! Who doesnt love their smell of perchloryl fluoride in the morning ? Anyone who's survived a spill of the stuff?
The paper goes on to react FOOF with everything else you wouldn't react it with: ammonia ("vigorous", this at 100K), water ice (explosion, natch), chlorine ("violent explosion", so he added it more slowly the second time), red phosphorus (not good), bromine fluoride, chlorine trifluoride (say what?), perchloryl fluoride (!), tetrafluorohydrazine (how on Earth. . .), and on, and on. If the paper weren't laid out in complete grammatical sentences and published in JACS, you'd swear it was the work of a violent lunatic. I ran out of vulgar expletives after the second page. A. G. Streng, folks, absolutely takes the corrosive exploding cake, and I have to tip my asbestos-lined titanium hat to him.
Not sure if A. G. Streng is still around, low odds i think
it is more powerful even that elemental fluorine due to the reduced bond F-F to Kr-F with redox potencial of 3.5, making it the most powerful known oxidising agent, though KrF4 could be even stronger.
The reasons for not doing so have mostly to do with the political systems of the world not being in support of that idea or effort, and the populations of the world are far too ensconced in daily survival to contemplate any larger human destiny than seeing another sunrise. In my view, an off-planet society, economy, and frontier on Luna and Mars would be sufficient for the foreseeable future. There would probably be a good development path on SEP and similar propulsion systems, once a regular cycling paradigm could be established.
I typically look askance at all the antimatter and other exotic proposals. But that's just me.
I made an attempt to collect at least the top five reasons that most of the so-called advanced propulsion ideas are not viable, but my choice of topic title was insufficiently non-judgemental:
my personal view is that in the far,far, far future flying around in spaceships will be redundant. It seems to me the only way of crossing vast tracts of spacetime is not to try and fly through it as it takes too long and too much effort. Rather we know spacetime can be bent and shaped. One day if we could control the bending of spacetime then I envisage that travelling anywhere in the universe would be the same as stepping through a door. How I imagine this would be like to use would be to step up to a door of a room/machine. On the other side, the destination you want to go too (anything from the most distant galaxy in the universe to the local shop down the road, would have spacetime bent to such an extent that your destination is now positioned on the other side of the door. you open the door (the door opens for you) you step across and are standing at you destination. the whole of the space time instantaneously unbends and returns to the its original position with you standing on it. maybe not even a room just an wearable device that bends you destination to appear before you; either way vast travel would be done in one step.no need to fly around in metal tubs, the only problem is we would all get exceedingly fat as we'd not have to actually walk anywhere any more
It is not political support it is cost!! Only three countries can put people in space.And I don't see that changing any time soon!! If may be lucky one or two more countries in next 20 years from now.
Europe does not have money and can hardly run welfare state.
Poverty is still major problem even in rich countries and health care is not what doctors will like to have it.Money money money is big problem and government does not have cash for billion dollars mars exploration that alone trillion dollar for mars colony that would have to be support like the Antarctica to planet terraforming is in place that would take a very long time and cost trillions , trillions , trillions , trillion of dollars.
chemical propulsion is not going to get us to other star system ever. Even Ion or plasma does not even get close.
Well fission or fusion will get you close to the speed of light and anti-matter almost at the speed of light.
No exotic propulsion system will get you faster than speed of light that is impossible by the laws of physics.With out warp drive even with anti-matter you will never travel less than 1% in the milky way even in generation ship. The milky way just too big.
I have not seen threads but we have to talk reality not fantasy.You can't say forget Ion , plasma , fission or fusion it will not get us use less than 1% in the milky way even in generation ship that talk warp drive.
We do not even know if warp drive or some thing like a warp drive is even possible or even clue how to build it.
Quote from: JasonAW3 on 05/27/2014 08:33 pmOk,Simple answers.Chemical rockets have an upper limit as to how fast they can go with a given amount of fuel.Ion Rockets can go really fastwith very little fuel but don't put out a lot of thrust initially and take a LONG time to get up to speed. (Not powerful enough to lift of the planet.)The idea behind Fission and Fusion rockets is to get the fuel REALLY hot so it expands faster than the fuel from a chemical rocket would. The advantage here is that you can get a lot of thrust for a much smaller amount of fel than it would take for a chemical rocket, (Good for boosting to orbit), and once in space, it could give a big initial push and be throttled back for a continious thrust, similar to the Ion engine.Problem is, Fission engines require a nuclear reactor which will involve radioactive materials. An accident could contaminate a large area. And we haven't quite figured out Fusion Rockets or reactors yet, but there's been some very promising developments on this over the last year or so.Anti-matter could take a mass of anti-matter about the size of a quarter and slowly combine it with an equal amount of matter and produce enough thrust to go ANYWHERE in the solar system in a few weeks, under a continious thrust. Problem here, we still don't know how to make large quantities of anti-matter and haven't quite licked the problem of containing the antimatter for storage, let alone trickle it out as a fuel source.Hope this tells you what you wanted to know.JasonAW3 your reply answers other propulsion systems. I'm still interested why Chemical rockets have an upper limit? Is it higher energy density or it the chemical that they use determine if it is dangerous and hazardous?If it is the chemicals? If it is the chemicals there still may be a fuel source they have not found or have to make that it is not dangerous and hazardous.If it is higher energy density that will not matter.So no idea where this chemistry imposed on rockets came from if it has nothing to do with energy density that are dangerous and hazardous but the chemical.
Quote from: micawber on 06/03/2014 02:05 pmmy personal view is that in the far,far, far future flying around in spaceships will be redundant. It seems to me the only way of crossing vast tracts of spacetime is not to try and fly through it as it takes too long and too much effort. Rather we know spacetime can be bent and shaped. One day if we could control the bending of spacetime then I envisage that travelling anywhere in the universe would be the same as stepping through a door. How I imagine this would be like to use would be to step up to a door of a room/machine. On the other side, the destination you want to go too (anything from the most distant galaxy in the universe to the local shop down the road, would have spacetime bent to such an extent that your destination is now positioned on the other side of the door. you open the door (the door opens for you) you step across and are standing at you destination. the whole of the space time instantaneously unbends and returns to the its original position with you standing on it. maybe not even a room just an wearable device that bends you destination to appear before you; either way vast travel would be done in one step.no need to fly around in metal tubs, the only problem is we would all get exceedingly fat as we'd not have to actually walk anywhere any more Even with warp drive it will take you centuries to to travel from one galaxy to next galaxy.
Quote from: nec207 on 06/03/2014 06:20 pmQuote from: micawber on 06/03/2014 02:05 pmmy personal view is that in the far,far, far future flying around in spaceships will be redundant. It seems to me the only way of crossing vast tracts of spacetime is not to try and fly through it as it takes too long and too much effort. Rather we know spacetime can be bent and shaped. One day if we could control the bending of spacetime then I envisage that travelling anywhere in the universe would be the same as stepping through a door. How I imagine this would be like to use would be to step up to a door of a room/machine. On the other side, the destination you want to go too (anything from the most distant galaxy in the universe to the local shop down the road, would have spacetime bent to such an extent that your destination is now positioned on the other side of the door. you open the door (the door opens for you) you step across and are standing at you destination. the whole of the space time instantaneously unbends and returns to the its original position with you standing on it. maybe not even a room just an wearable device that bends you destination to appear before you; either way vast travel would be done in one step.no need to fly around in metal tubs, the only problem is we would all get exceedingly fat as we'd not have to actually walk anywhere any more Even with warp drive it will take you centuries to to travel from one galaxy to next galaxy.This cant be stated with any certainty. No one knows any of the limits of faster than light travel, or if its even possible.
Quote from: nec207 on 06/03/2014 06:14 pmIt is not political support it is cost!! Only three countries can put people in space.And I don't see that changing any time soon!! If may be lucky one or two more countries in next 20 years from now.If Skylon works that will change quite substantially.
Quote from: nec207 on 06/03/2014 06:14 pmWe do not even know if warp drive or some thing like a warp drive is even possible or even clue how to build it.Not really. We have clues on how to build warp drives. If the clues lead to anything, that's another question.Dr Sony White , if i am not mistaken, believes he can create exotic matter from vacuum or something.