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People have forever said things are not possible based on their lifetimes worth of specialized knowledge, only to be proven wrong once the effort to make things happen; flight and space travel are two of the famous examples actually.
Today there is so much more knowledge, who know's what's possible? We'll never know till somebody tries; seriously, who's tried to colonize outerspace? Nodoby!
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There are two differences though...
Back when they said space flight would never be practical or even heavier-then-air flight was never going to happen, they were using the physics we have today, there was nothing that violates Newton in the Wright Flyer nor the Space Shuttle.
Today however, we are limited by the strength and power available in the atoms themselves, and we can't make new atoms, we are stuck with the ones we have. Sure we might get a little better at arranging them, but stuck with them we are.
[i]"The power of accurate observation is often called cynicism by those that do not have it." - George Bernard Shaw[/i]
[i]The glass is at 50% of capacity[/i]
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Atoms are made up of combinations of descrete building blocks, protons and neutrons, distantly sheathed in electrons. The number of protons and neutrons determine the mass and chemical/nuclear properties of an atom.
Atoms with about 100 protons or more and ~150 neutrons are inherintly unstable, because protons are electrically charged they repell eachother more strongly then the binding force that keeps smaller atoms together. This binding force has a finite maximum which is an unchangeable physical constant of the universe, beyond which an atom cannot keep its particles together and flies apart spontainiously.
For rocket fuel and materials, the drive is to make lighter and lighter atoms perform a given task, hence reducing the mass. We are already very close to the theoretical limits because we already have atoms with the minimum number of protons/neutrons that still have the desired properties. Hydrogen, the rocket fuel of choice, has just one proton and zero neutrons. It is the lightest possible atom, since you cannot have an atom with no protons or a fraction of a proton.
Oxygen has only sixteen total protons and neutrons, which is the lowest number that has both strong chemical oxidizing power and low toxticity. There are no atoms with fewer numbers of particles that have these properties, hence Oxygen is the lightest possible practical oxidizer.
Carbon, which makes up the bulk of composites, only has twelve particles, and is the only substance known that can make covalently bonded structures of arbitrary size. There are no other atoms lighter then carbon that does this, therefore carbon composite is probobly the lightest possible material. Lithium metal is the only lighter practical solid, but it is too soft to build structures out of.
There are various tricks we can use to make better use of these atoms, like condensing Hydrogen molecules down to lower temperatures with higher density, making chemically strained molecules of oxygen, or very large one-dimensional carbon molecules... but we are stuck with the atoms we have.
The periodic table, as far as everything except nuclear physics is concerned, is complete. There will be no more atoms.
[i]"The power of accurate observation is often called cynicism by those that do not have it." - George Bernard Shaw[/i]
[i]The glass is at 50% of capacity[/i]
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People have forever said things are not possible ... seriously, who's tried to colonize outerspace?
I don't think we have to jump from a debate about the feasability of colonizing space to synthetic atoms. By the way, Fermilab regularly accelerates protons to so much velocity that when they strike a target their kinnetic energy is converted into new subatomic particles. That's a conversion from electricty to run the accelerator into matter. But atoms are well catalogued. We could theoretically create huge subatomic particles by using the "strange" quark, but why? Such exotic physics isn't necessary to colonize space. We don't need anything more than we have now to colonize space. All we need is the will to do it.
We could build space colonies that don't require massive imports from Earth. That's the simplest way to avoid the cost of launch vehicles: don't use them. But other launch technologies are possible: SCRAM jet or nuclear thermal.
One way nuclear thermal has increased it's specific impulse is simply to increase temperature. New materials permit higher temperature. Timberwind had 1000 second Isp with a pebble bed reactor. I keep asking about fast reactors to reduce the mass of fission material. What about a fast gas core reactor? Could we keep uranium fluoride ([tex:55c5555503]UF_6[/tex:55c5555503]) in relatively narrow tubes of boron-11 and cadmium, and feed a fission reactor for combustion rate reaction? Neutron absorber tank walls should prevent unwanted reaction, and [tex:55c5555503]UF_6[/tex:55c5555503] boils at 56.6°C providing a gas nuclear fuel to feed into the reactor. A rapid reaction gas core nuclear thermal rocket should work with very small nuclear core, wouldn't need to maintain much of the nuclear material in the reactor since it's replaced so quickly, and small fission mass means light weight. Jet engine ceramics already permit gas temperature to 2700°C without regenerative cooling. Using liquid hydrogen as propellant can convert reactor heat into gas pressure, and that cold can be used for regenerative cooling. This permits higher temperature exhaust so higher Isp. Inconel 617 can operate at 1000°C (1832°F), Inconel 718 at 704°C (1300°F), and titanium alloy cooler yet. But rocket engines can use regenerative cooling to operate with high temperature exhaust. Timberwind had exhaust temperature of 2750°C. Using aircraft ceramics for together with regenerative cooling should permit extreme exhaust temperature. High gas temperature results in high pressure, which means higher exhaust velocity and higher specific impulse.
Gas pressure is directly proportional to temperature in degrees Kelvin. If you can double the temperature in °K you double pressure. I found this web page to calculate specific impulse. Exhaust velocity full equation is [tex:55c5555503]V_e ^2=kR_{gas}T_c[1-(p_e/p_c)^{(k-1)/k}]/(k-1)[/tex:55c5555503] but that can be simplified as a close approximation to [tex:55c5555503]V_e ^2=R_{gas}T_c[/tex:55c5555503] where
[tex:55c5555503]V_e[/tex:55c5555503] is exit velocity
[tex:55c5555503]T_c[/tex:55c5555503] is temperature in combustion chamber in °K
[tex:55c5555503]R_{gas}[/tex:55c5555503] is RR/MM
RR is universal gas constant
MM is exhaust gas molecular weight
[tex:55c5555503]I_{sp} = V_e / g_e[/tex:55c5555503] where
[tex:55c5555503]g_e[/tex:55c5555503] is gravitational attraction of the Earth (9.8 m/s[tex:55c5555503]^2[/tex:55c5555503])
This means specific impulse increases as the square of the increase in combustion chamber temperature. So a gas core nuclear thermal rocket with regenerative coolling and made of aircraft engine ceramics should produce [tex:55c5555503]I_{sp}[/tex:55c5555503] of 4000 seconds in vacuum. Radioactive fission fragments will come out the exhaust, so it's only for use in space, not ground launch. Is this beginning to sound feasible?
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Chemists explain propulsion as if it's the only way we are ever going to get anywhere. Angels don't ride in rockets.
We are just scratching the surface of what the universe is really made of. Atoms are like buildings compared to the tiny things that make them up.
And one of the things we need to figure out is the minute energy fields that those tiny particles have. Those tiny energy fields affect the universe.
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I don't think that you've done your math right Robert, the Timberwind engine already operate at ~3000K, but their Isp can't top ~1000sec. You need temperatures in the low tens of thousands of degrees to achieve a 4000sec specific impulse. The SSME engine runs at around 3600K, but only hits ~450sec. Something isn't right here, but electron diffraction class has my math abilities worn out for the day.
Don't you think someone would have thought of that already after all the trouble involved with NTR engines in the past if it were that simple and radically superior?
Your engine should also account for the different atomic masses of the Hydrogen and the UF6 you are dumping overboard, since the nuclear fuel will comprise a nontrivial componet of propellant.
Also, how does the fuel remain localized long enough for it to stay supercritical to heat the propellant? The vortex reactor, perhaps supplimented with magnets, in the "traditional" GCNR arrangement is the way to go.
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Dook, are you talking about Zero Point Field energy? ZPE is not so much "energy" persay as the physical manifestation of the Heisenberg Uncertainty Principle on the quantum scale. It is not a source of energy, because it will always take more energy to access ZPE then you will get from it.
And who said anything about chemists? Blame that on Ike Newton.
[i]"The power of accurate observation is often called cynicism by those that do not have it." - George Bernard Shaw[/i]
[i]The glass is at 50% of capacity[/i]
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Are you the same GCNRevenger who created the profile? With people scamming others' profile I have to ask. What I described is a trivial modification of the Gas Core Nuclear Rocket. I thought you (or your profile) started by raving how wonderful that is.
Actually, after posting this I looked up the basic GCNR. It's supposed to have Isp between 3000 and 5000 seconds, so I guess I re-invented the wheel. The basic model is supposed to have a vortex recirculating the gasseous uranium. Using uranium hexafluoride makes it easy to gassify. It's expected to loose some fissile gas to the exhaust flow, but they designed it to minimize that.
The only difference I'm making is to increase the fission rate so we can reduce the size of the reactor, and controlling loss of fissile gas isn't so criticial. It also reduces the mass of fissile material that must be carried. Typical rocket trips fire the engine for a few minutes but reactors are designed to operate for years at a time. A fast reactor can carry less uranium while producing the same heat, it just runs out of uranium quicker. But there isn't a need to carry uranium that will last longer than propellant, so a fast reaction can reduce launch mass.
Sublimating UF6 from solid into gas will require heating it to +56.6°C (133.88°F), but that can be accomplished by an electric heating element. A sustained burn main require replacing UF6, but the heat of the engine itself can sublimate UF6 from storage. Reaction rate can be increased with reduced uranium by surrounding the reactor with a neutron reflector. It's pretty standard now to surround an NTR engine with rods that can be rotated; reflector on one side, absorber on the other. Beryllium is an excellent light-weight reflector, boron-11 and cadmium make great absorbers.
If the reaction mass is kept to a minimum, it may be necessary to provide a flash of neutrons to start the reactor. Especially if timing rocket ignition is critical for navigation. I could explain some methods to generate a burst of neutrons, but since they're part of a fission bomb I won't publish it publicly.
As for temperature, note the exhaust temperature of SSME is enough to melt the bell cone nozzle if it didn't have regenerative cooling. It makes a big difference. If you don't believe me, then believe the guys who said GCNR can produce 3000 to 5000 second Isp.
As for the difference between NTR and chemical engines; yes, reducing propellant to just hydrogen does dramatically reduce propellant mass and consequently Isp. It does require super-heating hydrogen, but that's done with the reactor. Yes, this was realized long ago. Science fiction authors wrote about it; Robert A. Heinlein wrote "The Man Who Sold the Moon" in 1949. NASA built the NERVA engine in the 1960s, was completed and ready for space tests in 1972. At that time it's Isp was 800 seconds, they didn't have modern high temperature ceramics.
Um, magnets?
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No, I just don't think your design and associated assumptions/calculations will work. It really annoying when you "oh its so simple!," when of course it isn't, especially with my favorite technology.
First off, you are talking about pushing the nuclear reaction faster then I think you can, since the UF6 will dissapate rapidly in the liquid hydrogen stream, thus losing criticality plus defeating the purpose of heating propellant in the engine.
Second, the majority of the Uranium in a vortex GCNR engine is retained in the core, whereas your engine simply dumps it overboard. In this way, a vortex engine could use less Uranium overall, particularly for a smallish modest thrust engine. And of course both engines would have neutron reflectors, there is no good reason not to.
What I was pointing out about your engine, Timberwind, and the SSME is that all of them generate temperatures in the 3000K region, but neither one generates Isp in the thousands of seconds region. Since temperature is the controlling factor, something is wrong here, this was included as a check that your math doesn't make sense. Timberwind was to operate at 3000K but only achieved a quarter of this Isp. The VASIMR engine has to heat Hydrogen to hundreds of thousands or even a million degrees to achieve its ~10,000sec Isp, and I think you would have to hit tens of thousands to reach Isp >2000sec for a GCNR engine.
...And if you can reach those kinds of temperatures, the fissioning Uranium is no longer a gas, but a plasma, and as a plasma it can be repelled by a magnetic field. Since a vortex GCNR engine will be roughly toridal shaped, this is quite convienant, and will permit the Uranium to be further confined and compressed to raise temperatures even higher.
Edit: A GCNR engine is going to need to hit temperatures in the 50,000K region to achieve really high Isp values, so sayith various articles on the topic. I might see if I can fix your math if I get the inclination.
[i]"The power of accurate observation is often called cynicism by those that do not have it." - George Bernard Shaw[/i]
[i]The glass is at 50% of capacity[/i]
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What I'm talking about is this, once we figure out gravity we can use it to explore the universe.
But still, angels don't use starships.
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What I perhaps didn't emphasize enough is the vortex will still be there. However, I expect the direct gas-to-gas heat exchange will result in much of the uranium gas to be expelled with the hydrogen exhaust. That's one reason I want rapid fission reaction, so uranium can be replaced fast enough to replace the loss without expelling any significant amount of unreacted uranium. That means ensure what you expel is primarily fission fragments, not uranium.
Starting the gas core nuclear reactor won't be easy. Uranium metal melts at 1132.2°C (2070°F) and boils at 3927°C (7101°F). How do you expect to achieve that without an operational nuclear reactor? How do you expect to get it started? Uranium hexafluoride permits gasification at temperatures practical with a simple electric heating element. If the gas core does reach the temperature you recommend, it will dissociate the UF6 molecule leaving mono-atomic uranium and fluorine. The fluorine will move more quickly and be drawn off with the hydrogen, leaving pure uranium gas. Sounds like a start sequence to me. Furthermore, injecting additional UF6 gas is a simple and practical means to replace losses from exhaust.
If it sounds like I make it sound too simple, there's a reason. Ever since the first flight of the Space Shuttle, major contractors have complained that any new technology is too difficult. They used that excuse to increase the cost, gouging the American taxpayer. To this end they deliberately dragged out any new technology development program until NASA or Congress got tired of the scam and cancelled it. What I'm saying is it can be done; it doesn't have to be built from "unobtainium". You see, when I say "oh its so simple", what you should read is "it can be done, and done quickly". The excuse that this or that is too difficult only results it stalling any progress. It's time to get off the pot and get to work.
As for nuclear rockets specifically, the political environment that permits them is running out. Before George W. Bush it was politically impossible to work on any nuclear power for space, even reactors much less rocket engines. Anti-nuclear activists have no political clout during George W.'s administration, but American law has a term limit so he can't run for re-election on November 4, 2008. America will probably have a Democrat president after that. Regardless who is in power, will the new president listen to anti-nuclear activists? Will it become impossible to develop nuclear rockets? A GCNR expels highly radioactive fission fragments in its exhaust, not at all applicable for ground launch or operation within the atmosphere. Will activists claim it will somehow contaminate the atmosphere? Development requires test firing; will activists demand any such engine be prohibited even in a contained ground test facility? Bottom line: it's time developers get off their ass and do it now while it can still be done.
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"so I guess I re-invented the wheel"
No kidding... except your math is messed up and your choice of materials would cause it to melt.
I don't think its practical to make a nuclear reaction fast enough to avoid needing excessive amounts of Uranium. You need to maintain a critical mass in the engine at all times, preferably as tightly confined as possible. Thats not going to happen if you are flushing it continuously along with the propellant. The mass of the Uranium is going to offset the low mass the Hydrogen and lower specific impulse somewhat too.
1000C should not be too hard to achieve, since the core will go critial without having to melt, just a criticality of uranium being confined in the LH2 should do just fine. Small metal pellets would work here probobly, that failing UF6 could also be used, but it will be harder to force it to settle to the center of the vortex.
"If it sounds like I make it sound too simple, there's a reason. Ever since the first flight of the Space Shuttle, major contractors..."
You want hard? Its hard to take you seriously about anything, because you keep on saying its so easy, then you come up with some hair-brained duct-tape/chewing-gum arrangement, and blaming the lack of such an arrangement on "evil capitalists."
The fact of the matter is, that the engine will have to attain temperatures and energy flux that will be difficult to deal with, despite the copius quantities of liquid hydrogen involved. It would be a serious and expensive undertaking, and I have doubts that materials science is up to the task yet. It might be possible today, and it might not be, but it would surely be difficult... Probobly as hard or harder then NERVA or SSME development.
"As for nuclear rockets specifically, the political environment that permits them is running out."
Says you. I think a poll some time ago showed that ~60% of Californians want more nuclear energy. The power of the nuclear activists is waning. We have facilities right now for engines up to 10,000lbs thrust if memory serves, and when Yucca mountain and the new breed of reactors comes online in the next decades, we'll be ready for GCNR politically.
[i]"The power of accurate observation is often called cynicism by those that do not have it." - George Bernard Shaw[/i]
[i]The glass is at 50% of capacity[/i]
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Politics is very fickle. Throughout the 1990's, Paul Martin was the finance minister. Prior to 1993 he was the second place contender for party leadership. After he fixed the country's financial problems he was seen as the next Prime Minister. The late 2003 leadership convention was seen as a coronation. However, opposition political attacks and sabotage from the out-going Prime Minister caused loss of support. He lead a minority government for 17 months, then lost the election last month. So much for the most loved political leader in remembered history.
Nuclear power makes a lot of sense. I don't think I need to argue why. However, politics is fickle. If the incoming President in 2008 uses anti-nuclear activists as his/her political base, that could sway favour strongly. Voters support a winner, a politician wins from support; it's an unstable positive feed back loop.
By the way, the campaign manager in our riding has a business as a councillor; as in therapist. Would you like me to introduce you to him? It sounds like you need one.
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If we stay here on earth, energy problems will mount; defining earth as a closed system is relative, but it is closed enough with respect to human technological species needs.
In other words, space colonization, or forget civilization. Cost? Who knows? And, as essentially the point of this thread, who cares!? You never know what you'll find as far as methodologies out there in outerspace.
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once we figure out gravity we can use it to explore the universe.
How do you know? We haven't figured it out yet.
We will quite possibly explore the universe with things we have not yet even begun to dream of.
Far out in the uncharted backwaters of the unfashionable end of the Western Spiral arm of the Galaxy lies a small unregarded yellow sun.
-The Hitchhiker's Guide to the Galaxy
by Douglas Adams
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He may be right.
Physicist to Present New Exact Solution of Einstein's Gravitational Field Equation
New antigravity solution will enable space travel near speed of light by the end of this century, he predicts.
On Tuesday, Feb. 14, noted physicist Dr. Franklin Felber will present his new exact solution of Einstein's 90-year-old gravitational field equation to the Space Technology and Applications International Forum (STAIF) in Albuquerque. The solution is the first that accounts for masses moving near the speed of light.Felber's antigravity discovery solves the two greatest engineering challenges to space travel near the speed of light: identifying an energy source capable of producing the acceleration; and limiting stresses on humans and equipment during rapid acceleration.
"Dr. Felber's research will revolutionize space flight mechanics by offering an entirely new way to send spacecraft into flight," said Dr. Eric Davis, Institute for Advanced Studies at Austin and STAIF peer reviewer of Felber's work. "His rigorously tested and truly unique thinking has taken us a huge step forward in making near-speed-of-light space travel safe, possible, and much less costly."
The field equation of Einstein's General Theory of Relativity has never before been solved to calculate the gravitational field of a mass moving close to the speed of light. Felber's research shows that any mass moving faster than 57.7 percent of the speed of light will gravitationally repel other masses lying within a narrow 'antigravity beam' in front of it. The closer a mass gets to the speed of light, the stronger its 'antigravity beam' becomes.
Felber's calculations show how to use the repulsion of a body speeding through space to provide the enormous energy needed to accelerate massive payloads quickly with negligible stress. The new solution of Einstein's field equation shows that the payload would 'fall weightlessly' in an antigravity beam even as it was accelerated close to the speed of light.
Accelerating a 1-ton payload to 90 percent of the speed of light requires an energy of at least 30 billion tons of TNT. In the 'antigravity beam' of a speeding star, a payload would draw its energy from the antigravity force of the much more massive star. In effect, the payload would be hitching a ride on a star.
"Based on this research, I expect a mission to accelerate a massive payload to a 'good fraction of light speed' will be launched before the end of this century," said Dr. Felber. "These antigravity solutions of Einstein's theory can change our view of our ability to travel to the far reaches of our universe."
More immediately, Felber's new solution can be used to test Einstein's theory of gravity at low cost in a storage-ring laboratory facility by detecting antigravity in the unexplored regime of near-speed-of-light velocities.
During his 30-year career, Dr. Felber has led physics research and development programs for the Army, Navy, Air Force, and Marine Corps, the Defense Advanced Research Projects Agency, the Defense Threat Reduction Agency, the Department of Energy and Department of Transportation, the National Institute of Justice, National Institutes of Health, and national laboratories. Dr. Felber is Vice President and Co-founder of Starmark.
Source: Starmark
"Yes, I was going to give this astronaut selection my best shot, I was determined when the NASA proctologist looked up my ass, he would see pipes so dazzling he would ask the nurse to get his sunglasses."
---Shuttle Astronaut Mike Mullane
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Suuuure, whatever... any time I hear "solves" and "Einstein" in the same breath, my crackpotometer spikes.
[i]"The power of accurate observation is often called cynicism by those that do not have it." - George Bernard Shaw[/i]
[i]The glass is at 50% of capacity[/i]
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yes, I'm also a bit wondering about this one; i saw a similar article at newscientist about some poor physicist whose had ufo's figured out since the 80's; something about his equations are succesfull in prediction quantum particle masses; well, anyways . . . .
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Felber seems to be real and so does his presentation at STAIF 2006 (last on the agenda) along with a bunch of other people from serious organizations such as NASA, ARFL, Boeing, DoD etc etc.
[color=darkred]Let's go to Mars and far beyond - triple NASA's budget ![/color] [url=irc://freenode#space] #space channel !! [/url] [url=http://www.youtube.com/user/c1cl0ps] - videos !!![/url]
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I hope he is right.
http://www.space.com/businesstechnology … avity.html
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