Nuclear rockets are very very very bad idea?

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nec208

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People say lots of smoke and dust is generated at the launch site and do you want that pullution of nuclear . Well airborne radioactive matter people will breath when the nuclear rocket is going up.

Also safety concerns look at Challenger and the Columbia? With radioactive waste being spread through the atmosphere by the explosion.
 
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RVHM

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Nukes are perfectly safe to use without human error. If the people handling them are retards, that is the problem... :roll:
 
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orionrider

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People say lots of smoke and dust is generated at the launch site and do you want that pullution of nuclear . Well airborne radioactive matter people will breath when the nuclear rocket is going up.
Nuclear propulsion is for use in space, not for take-off.
No radioactive 'dust' is released when the rocket leaves the ground.
 
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Boris_Badenov

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NuclearSpace.com

There are many different types of Nuclear Rocket Engines. Lumping them all into the "THEY ALL BE EVIL" category is someting I'd expext to see on a PETA forum.
Simply put, if we never use Nuclear Power in space for exploration & colonization we will never explore or colonize the Solar System.
 
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pathfinder_01

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nec208":1r34nu82 said:
People say lots of smoke and dust is generated at the launch site and do you want that pullution of nuclear . Well airborne radioactive matter people will breath when the nuclear rocket is going up.

Also safety concerns look at Challenger and the Columbia? With radioactive waste being spread through the atmosphere by the explosion.
ISP isn’t everything. Nuclear rockets don’t make good first stages or frankly good rockets for putting something into orbit. They are meant for in space propulsion. For a rocket esp. the first stage of one thrust is more important than fuel efficiency.

Also that radioactive exhust is quite toxic to anyone near it not to mention what if this thing crashes? You really do not want the airbone release of radioactive materials.

If you want to reduce the cost of getting into space focus on other things. Propellant is cheap. The value of the propellant in the shuttle fuel tank is something like $500,000 which is nothing compared to the hundreds of millions spent on the mission and billions spent to keep the shuttle running. To reduce the cost of spaceflight you need rockets that take fewer man hours to build and launch and rockets that are made via cheaper materials and lower price processes. The normal evolution of technology will give us that if new designs and new methods are allowed to be tried out. If reuse can be made practical that will reduce costs as well.

The biggest falure of the shuttle really wasn’t that it wasn’t as cheap as promised. The biggest faluire of NASA was in keeping the thing 30 years. If newer versions had been developed ten years ago and ten more years there would be a chance that those versions would be cheaper. However when you keep a system that long the only chance you can make it cheaper is through amortization of costs.

Anyway the role of nuclear and electric propulsion isn’t in putting things into space. It is in making it easier/cheaper/faster to get to your destination. The reason why the Saturn V was so massive was because of the amount of chemical propellant that needed to be put into LEO in order to reach the moon. If it were possible to use electric propulsion to get to the moon manned you could launch it on a rocket that puts 20-30 tons into orbit instead of needed one that put 110. Of course the slow trip times to the moon makes electric useless for a manned trip but for cargo it would be cheaper.

Nuclear on the other hand, unless it is a reactor powering an electric propulsion system probably is not practical.
 
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DarkenedOne

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nec208":1q5cvri7 said:
People say lots of smoke and dust is generated at the launch site and do you want that pullution of nuclear . Well airborne radioactive matter people will breath when the nuclear rocket is going up.

Also safety concerns look at Challenger and the Columbia? With radioactive waste being spread through the atmosphere by the explosion.
Orionrider is right nec28.

No one is proposing that open core nuclear rockets be used on Earth. The idea for nuclear rockets is for use in space travel only. Regular chemical rockets would be used to transport the nuclear rockets into Earth's orbit. Nuclear reactors emit negligible radiation until they are turned on. Thus the reactors will not be radioactive when they are launched thus eliminating the chance of radioactive fallout in case of a failed launch. Once in orbit the nuclear rockets will propel people to places like the Moon and Mars far faster, cheaper, and more efficiently than chemical rockets.

I suppose it is possible to engineer a closed loop design for use on Earth. It would be a challenge to achieve the thrust to weight ratios needed with all of the extra shielding.
 
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nec208

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Boris_Badenov":luwxkvde said:
NuclearSpace.com

There are many different types of Nuclear Rocket Engines. Lumping them all into the "THEY ALL BE EVIL" category is someting I'd expext to see on a PETA forum..

What do you mean?

Nuclear rockets don’t make good first stages or frankly good rockets for putting something into orbit
Why is that?

radioactive 'dust' is released when the rocket leaves the ground.
From what people say they fear the nuclear rockets taking off from earth do to smoke and dust is generated at the launch site the pullution that is radioactive and if there is a explosion the radioactive fallout.

The biggest falure of the shuttle really wasn’t that it wasn’t as cheap as promised. The biggest faluire of NASA was in keeping the thing 30 years. If newer versions had been developed ten years ago and ten more years there would be a chance that those versions would be cheaper. However when you keep a system that long the only chance you can make it cheaper is through amortization of costs.
The shuttle is going to be retired.It will take 5 or 10 years for a replacement shuttle if all goes welll.
 
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pathfinder_01

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In order to take off from an earth your thrust to weight ratio must be one or higher. At the ground conditions are least favorable to the rocket. The dense atmosphere creates more drag than higher up or even in space where there drag is negilable. The earth’s gravity is at its strongest on the ground and gravity losses highest. Also rocket engines are generally optimized for a certain altitude and rockets in general work best in a near vacuum. The shuttle’s engines are optimized for 60,000 feet.

All these forces and factors acting against the rocket costs extra propellant which in turn cost extra mass which in turn makes getting into space harder.

In order to get into space with the least amount propellant it is best to get high above the earth as quickly as possible. This is why high thrust is so important in a first stage. For latter stages fuel efficiency could be more important. Off the bat nuclear rockets have less thrust than chemical rockets and even worse they mass a lot more. The terrible thrust to weight ratio makes them not a good choice for a first stage. The only time you might use one for a 1st stage is if you are taking off from another body and don’t want a chemical rocket for some reason.(i.e. you plan to use the stage again in space to return to earth). The higher your thrust to wiegh ratio the faster you will acelerate.

For instance the shuttle throttles its engines up to the limit at liftoff then as it approaches max q (the moment when aerodynamic forces are the greatest on the rocket) it throttles down for a while till it gets higher up in the atmosphere then throttles them up again.

Now there are limits to how quickly you can lift off. If your rocket accelerates too quickly the g forces could injure or kill the crew and should you need to use an emergency escape system the faster you accelerate the harder it is to design an escape system. Also max Q is when aerodynamic forces are the greatest on the rocket and the rocket faces a choice reduce the rate of your acceleration or be torn apart by aerodynamic forces. For instance in the Challenger disaster once the faulty solid clipped challenger’s wing and pivoted into the fuel tank, aerodynamic forces tore the shuttle apart. There was no explosion in the general sense of the word.
 
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annodomini2

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DarkenedOne":g3utifn2 said:
Thus the reactors will not be radioactive when they are launched thus eliminating the chance of radioactive fallout in case of a failed launch.
There's a flaw in that argument, you assume that the reactor isn't damaged from it's impact with the Earth.

Assumption is the mother of all f**k ups!
 
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wick07

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annodomini2":10xn7vhj said:
DarkenedOne":10xn7vhj said:
Thus the reactors will not be radioactive when they are launched thus eliminating the chance of radioactive fallout in case of a failed launch.
There's a flaw in that argument, you assume that the reactor isn't damaged from it's impact with the Earth.

Assumption is the mother of all f**k ups!
Actually, I would be less concerned by the impact with the earth than the reactor being torn apart from an explosion. If the reactor breaks apart on impact the contamination would be over a very limited local area. If it breaks apart in the atmosphere the contamination will be spread over a much larger area.
 
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DarkenedOne

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wick07":yj9uoo23 said:
annodomini2":yj9uoo23 said:
DarkenedOne":yj9uoo23 said:
Thus the reactors will not be radioactive when they are launched thus eliminating the chance of radioactive fallout in case of a failed launch.
There's a flaw in that argument, you assume that the reactor isn't damaged from it's impact with the Earth.

Assumption is the mother of all f**k ups!
Actually, I would be less concerned by the impact with the earth than the reactor being torn apart from an explosion. If the reactor breaks apart on impact the contamination would be over a very limited local area. If it breaks apart in the atmosphere the contamination will be spread over a much larger area.
There are no significantly radioactive materials in a nuclear reactor that has not been turned on. The reason is that radioactive materials are generated as a result of the fission process itself. The fuel, usually U-235, is not significantly radioactive. Therefore if the new nuclear reactor has never been turned on than no radioactive substances are generated. It is the same as here on Earth. When they build a nuclear reactor they do not have to worry about radioactivity. It is only after the reactor starts up and the fission process begins do they have to worry about radioactive substances.

I admit that this does pose a engineering challenge because it prevents you from fully testing the reactor on the ground.
 
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bdewoody

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The three shuttles that remain are not the same as they were in their original configuration. They have been modified and modernised throughout their careers. They are much safer now and could be further modernised to make them even safer. New materials for critical area heat shields have already been tested and could be incorporated into the shuttle fleet. All of the replacement components that are running short could easily go back into production with better parts than those that are being replaced.
 
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doom_shepherd

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nec208":2e7wwbyf said:
From what people say they fear the nuclear rockets taking off from earth do to smoke and dust is generated at the launch site the pullution that is radioactive and if there is a explosion the radioactive fallout.
The "people" you have been talking to are way off.

We don't, and aside from the theoretical Orion ship proposed back in the 70's never planned to, launch rockets using nuclear engines. Therefore no smoke or dust that is radioactive is possible.

We've used nuclear FUEL on Voyagers 1&2, Viking 1&2, Galileo, Cassini, New Horizons, and others I'm surely forgetting. You remember how they killed us? Me neither.

If I recall correctly, the containers for those nuclear fuel are tested for safety by ramming a locomotive engine (or the equivalent) into them. The chances of them breaking in the explosion of a rocket, in any way that could produce more than very localized damage, are very remote.
 
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drwayne

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Actually, I have been wondering if anyone in this discussion was referring to the Orion concept, which
was essentially a missile riding on top of a bunch of exploding nuclear bombs, and that was the
origin of the "dust".
 
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Delphinus100

Guest
If we want to go far, in anything remotely resembling reasonable times (even for distant unmanned probes), nuclear rockets, whether nuclear-thermal or nuclear-electric are not just a good idea, they're the only idea.

Period.

And where but in deep space where they're most needed, could they be less of a hazard?
 
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Delphinus100

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Nuclear rockets don’t make good first stages or frankly good rockets for putting something into orbit
Why is that?


Though I disagree with the author of this post on SSTO in general, he explains here why using a nuclear-thermal rocket (at least any that we could build with a thrust to weight ratio using available technology) is not an efficient way to do single-stage to orbit:

http://selenianboondocks.com/2010/06/ssto-ntr-bad/
 
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orionrider

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Riding the blast of a thermonuclear bomb is probably the least efficient way to travel in space, even if it is better than what we currently have. http://en.wikipedia.org/wiki/Nuclear_pulse_propulsion

When (if) nuclear fusion ever gets under control, spacecraft could do it in a regulated fashion, either using small pulsed or continuous detonations in a semi-open (EM?) containment chamber. Similar to a tokamak or VASIMR engine, but working at a level of energy several orders of magnitude higher.

There is also a good probability engineers will finally find a way to contain antimatter to be used as the perfect spacecraft propulsion fuel.

We're speaking centuries here, so don't get too excited ;)
 
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Valcan

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orionrider":3qxdan8i said:
Riding the blast of a thermonuclear bomb is probably the least efficient way to travel in space, even if it is better than what we currently have. http://en.wikipedia.org/wiki/Nuclear_pulse_propulsion

When (if) nuclear fusion ever gets under control, spacecraft could do it in a regulated fashion, either using small pulsed or continuous detonations in a semi-open (EM?) containment chamber. Similar to a tokamak or VASIMR engine, but working at a level of energy several orders of magnitude higher.

There is also a good probability engineers will finally find a way to contain antimatter to be used as the perfect spacecraft propulsion fuel.

We're speaking centuries here, so don't get too excited ;)
So basicaly your saying there is no point to a space program besides launching satelites.....
 
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richcon

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nec208:

What's missing here I think is a clear explanation of what nuclear propulsion even is. It's not a rocket with nuclear explosions spewing out the back (though something like that was looked at many decades ago for use in space, and determined to be completely impractical.)

Nuclear propulsion is simply electric propulsion using a nuclear reactor for its electricity. And electric propulsion works by ionizing some kind of inert gas, like Xenon, to make it magnetic. Then a giant electromagnet pushes the gas out the back of the ship. This creates a very slow and steady thrust that's fuel-efficient (and not at all radioactive) — and in microgravity, fuel efficiency really is everything. But it's far too weak to use inside the atmosphere so it'll be launched using traditional chemical rockets. The nuclear reactor onboard provides the electricity and would be similar in concept to the reactors you find in submarines and other naval vessels today, and would be kept turned off at launch.

The reason it's important is that solar power is extremely weak when you go past Earth's orbit. At Mars, the sun is only about half as bright as it is at Earth, and by Jupiter it's so weak it's useless for electricity. All the space probes we've sent past Jupiter have used a sort of weak nuclear power: generating electricity from the heat given off by decaying plutonium.

And compared to these "weak" nuclear generators we're already flying, a real nuclear reactor would actually be safer at launch: Plutonium, if inhaled, is very carcinogenic. But a real reactor starts with Uranium (which is far less radioactive and already exists, in trace amounts, inside your body) and would only create plutonium once safely in outer space.
 
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SpaceJeff

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Before anyone else posts a reply, please read about NERVA rocket engines, a nuclear rocket engine designed in the 60's. They used a nuclear reactor that heated up liquid hydrogen very rapidly - no oxidizer necessary - and they obtained a much greater thrust-to-weight-of-fuel ratio than chemical rockets. They were designed to be used in space, as upper stages or as what, these days, are referred to as "Earth departure stages". There was a fairly significant level of radioactivity in their reactors, but as I understand it, the level of radioactivity in the exhaust was negligible. None were ever launched, but the R&S advanced to the point where NASA could have launched these engines into space. However, the public perception of the dangers of a "nuclear rocket engine" was sufficiently negative to make launch politically prohibited, whatever the actual merits and risks associated with the design. It just goes to show you that, when it comes to politics, the facts don't really matter.

When evaluating the risks of launching nuclear rocket engines into space (or any nuclear, or otherwise hazardous, propellant and/or cargo), you should consider the fact that a number of American and Russian nuclear submarines ended up being destroyed due to accidents (or that's the Defense Department's version of things, anyway), and their reactors are at the bottom of the ocean. Huge ecological disaster? If so, then the U.S. and Russia have kept it under wraps for decades - and I don't believe that the U.S. government could keep such a big secret for so long. I am not a big pro-nukes guy, but while there are risks involved in launching such materials into orbit, they're manageable.
 
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neilsox

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Other than RTG = radioactive thermal generator? we may never carry fueled nuclear reactors into space, due to the modest hazard to surface humans. The former USSR is an exception and there is some concern that these satellites will re-enter the atmosphere eventually. One that did, produced only a small amount of contamination in Northern Canada. In theory we can refine ore in asteroids to make nuclear fuel. This solves the problem, if the asteroid and the fueled space craft stay well away from Earth. If the ejection mass of a spacecraft has high radioactivity, we need to shut down the engine whenever the ejected mass is likely to be swept up by Earth in the next few centuries. This latter is likely a minor concern until we build very powerful ejection mass engines, which may be never. I do, however, agree that fission does make fast long range space travel possible, considerably beyond the limits of chemical rockets or other non-nuclear alternatives. Neil
 
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the_harper

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Just in case anyone is looking for a simple reference about NERVA:

http://en.wikipedia.org/wiki/Nuclear_thermal_rocket

The Wikipedia article about NERVA suggests that it was proposed for use in an upper stage of a modified Saturn launch system. I'd guess that a better use would be as the power source for an earth-moon shuttle, or an interplanetary vehicle never intended to make a landing such as the concept shown in 2001 a Space Odyssey. It would be an engine which would operate for a much longer time than a conventional rocket engine, but with lower thrust. In the Wiki article, the proposed fuel was liquid hydrogen.

I think a nuclear rocket would be a good idea with appropriate containment for specific purposes - such as long journeys to other planets where the engine only operates in space and in orbit.
 
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sonhouse

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It looks to me like we should at least pursue materials science to see if better fundamental materials research can find better core materials, etc. Meanwhile, it looks to me like it would be a lot cheaper to pursue the 'space elevator' concept since carbon nanotube research may solve the present problem of weak cables. If the cables can be made 100X stronger than steel, it would be a go. At that point, you could ship nuclear rockets to geo orbit and run the rest of the probes, manned and unmanned from there. The problem of SSTO would be a non-issue and the nuclear rocket or whatever propulsion system is developed at that time would have a real chance at a real space program. If you had a space elevator, you could also use high powered lasers, maybe even microwaves, to power craft with no power supply on board at all, just fuel and some kind of fuel heating system for thrust. It could be in another 100 years we will all have a big laugh over the efforts of people trying to make nuclear rockets when something much better is invented in the meantime.
What if we made a manhattan sytle project to engineer carbon nanotubes to space elevator strength? Seems to me a billion spent there would be well worth it. At least we could see how close we could come to space elevator strength.
 
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nec208

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What is the differnce of nuclear-thermal or nuclear-electric rocket.

And what happen to project orion or project daedalus they where nuclear and could take of from earth.
 
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pathfinder_01

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nec208":3849aqxg said:
What is the differnce of nuclear-thermal or nuclear-electric rocket.

And what happen to project orion or project daedalus they where nuclear and could take of from earth.
With a thermal nuclear rocket the nuclear reactor is used to heat the propellant that drives the rocket. In a chemical rocket the propelants mix in the combustion chamber and explode. This explosion is what cause the propelants to be acelerated out the end of the rocket. Solar thermal rockets use the sun to generate heat that in turn is used to force the propellant out. Nuclear thermal use an reactor. Both are more fuel effcient than a chemical rocket.

The trouble with nuclear thermal is that no material can stand the heat needed so the reactor is operated in a controled meltdown.

With nuclear electric propulsion the nuclear reactor is used to generate electricity which in turn is used by an electric rocket engine(ion, VASIMR, ect..) to move the craft. Electric rockets don’t care how the electricity is generated just that there is enough of it and that the power source does not mass too much. Manned missions using electric propulsion need a lot of power and thus nuclear reactors are the most likely way of making that power.

Cant give you the details, but Orion wasn't nuclear thermal or nuclear electric. For nuclear thermal look up NERVA.
 
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