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There are fully contained nuclear rockets. They are called gas core nuclear rockets, or nuclear light bulbs. The reaction uses uranium hexafluoride gas, spun into a vortex. This vortex is contained within a sealed, quartz walled chamber. The reaction produces a lot of UV radiation. Quartz is transparent to the UV radiation, so it escapes the container. Propellant is run past the quartz wall and absorbs the UV radiation, and heats up, expanding in the process. Voila, a nuclear rocket with no radioactive exhaust.

Oh come now! We've barely scratched the surface of what nuclear rockets can do.

What you really want is a gas core nuclear rocket. Because the core is gas, as opposed to solid or liquid, it cannot melt down. It can also reach higher operating temperatures, meaning more energy into the propellant.

But we can do it right. Stick some money into nuclear propulsion (not Orion, try a closed cycle gas core nuclear rocket). If we're not limited to chemical power we can lift a lot more weight. Make solar-power satellites, a real space station, and so forth. Open up whole new industries...

No. Nuclear to orbit. To get to orbit you needs oomph. Nuclear has got the strength, the oomph to get you to orbit. Once there, you can make do with ion drives, or magnetohydrodynamics, or whatever. Please note that I'm not talking about an Orion style, set nuclear bombs off under a pusher plate style of nuclear rocket. I'm talking about gas core nuclear rockets, or nuclear light bulb rockets as they're sometimes called. These do not spew radioactive waste out, as the reaction is completely contained.

No. Nuclear to orbit. To get to orbit you needs oomph. Nuclear has got the strength, the oomph to get you to orbit. Once there, you can make do with ion drives, or magnetohydrodynamics, or whatever. Please note that I'm not talking about an Orion style, set nuclear bombs off under a pusher plate style of nuclear rocket. I'm talking about gas core nuclear rockets, or nuclear light bulb rockets as they're sometimes called. These do not spew radioactive waste out, as the reaction is completely contained.

I hope somebody at NASA starts pushing for nuclear powered rockets based on Gaseous Core Nuclear Reactors. In a gaseous core reactor or "nuclear lightbulb" a cloud of gaseous uranium would be confined in the center of a sealed quartz bulb, by a buffer gas swirled around the inside of the bulb. The uranium gas heats up to 25,000C, emitting intense ultraviolet. Pure quartz is 100% permeable to UV, which passes through and heats a stream of liquid hydrogen flowing past the outside of the bulb. The superheated hydrogen expands and exits through a rocket nozzle to provide thrust. Keeping the nuclear fuel from touching anything overcomes the temperature limitation of solid fuel reactors, which can only be taken to about 3,500C without melting. They're also safe; completely destroying a GCNR in the atmosphere would release less than 1% of the nuclides from a single 1950 A-bomb test.

Here's an interesting hypothetical design for a 100% reusable, non-polluting GCNR-powered rocket using the Saturn-V form factor, which could life 1000 tons of payload into Earth orbit and return an equal size cargo to a fully powered landing. This rocket could launch a space hotel in a one shot or carry lavishly equipped missions to the moon or Mars, with dozens of crew and plenty of radiation shielding. True Buck Rogers style spaceships that take off and land vertically again and again.

A gaseous core reactor would radiate ultraviolet energy directly to the hydrogen, eliminating the need to generate electricity. Take a look at this article about a hypothetical design for a non-polluting, 100% reusable nuclear rocket using the Saturn V form factor that could lift 1000 tons of payload into Earth orbit and return an equal payload to a powered landing.

Other propulsions systems could make a round trip feasible by allowing solar powered launch.

Here's two.

It looks like this design is a combination of rocket engines and ramjets.

I want a moonbase too, but I don't care as much where we go on our next mission. To establish a meaningful, lasting presence in space, we must reinvent the launch vehicle. Current space missions are so expensive because of launch costs. Because launching is so expensive, payloads are much more expensive and limited as well, because they must be built with every ounce of weight carefully planned.

Rather than spending the next 20 years and billions of dollars on repeating the Apollo missions (or doing just slightly better), I'd rather we spent the effort on developing better launch technology. Once we can take larger loads to space for much cheaper, all sorts of space exploration will naturally follow, including a moonbase.

Ideas for how to build such a vehicle exist. My favorite is described here. Unfortunately, it is harder to gain support for such a plan, but if it's the plan with the best long term potential, we should be doing it.

I wish NASA would put more effort into developing gaseous core nuclear rocket engines. There was a nuclear engine project in the late 60s using a solid core reactor, but gaseous core reactors have not been thoroughly explored. Whereas solid reactors melt above about 3500C, a "light bulb" type of reactor consisting of a hollow quartz bulb with a cloud of gaseous nuclear fuel confined in the center could operate at 25000 C, radiating in the ultraviolet range instead of heat per se. In an engine based on this type of reactor, hydrogen flowing past the outside of the bulb would be superheated and expelled as rocket exhaust. No chemical combustion, no radioactive emissions, just heat transfer.

Check out this interesting article, part 10 of a series, about a hypothetical design for a non-polluting, 100% reusable nuclear rocket based on the Saturn V form factor. Using existing engineering apart from the gaseous core reactor, it could lift 1000 tons of payload into orbit (6 times the capacity of the proposed single-use Ares 5 cargo rocket, and 30 times that of the shuttle), and then return 1000 tons of cargo to a powered vertical landing. No expendable fuel tanks, no solid booster recovery, just a big old Flash Gordon style rocketship. This is heavy lifting power that could take up a space hotel or moon base in one shot. It could power enormous ships to Mars in 3 months, not merely to explore but to colonize, carrying hundreds of people at a time, hundreds of tons of equipment and supplies, and highly effective radiation shielding.

I know it's the "N" word, but this rocket wouldn't be a nuclear disaster waiting to happen. If such a ship crashed or exploded and released its entire nuclear fuel load into the atmosphere, the nuclides released would be 1% of what came out of a single 1950s bomb test (and there were many of those).

This has plenty of military applications, as well. Space is the ultimate "high ground" and a dominant U.S. presence in space should have obvious strategic benefits.

Of course, at the same time we can work on more efficient techniques for utilizing the oil we do need. Cars with better mileage (improving our overall fuel efficiency by less than 3mpg would eliminate our need to import oil from the Persian Gulf), more efficient means of generating and using fertilizers, a bit of thought about how we use plastics, etc. Even better, we can sell the technology we develop to other parts of the world - further reducing world demand for oil, driving the price down. The lower the price of oil, the less funds the Islamist fanatics have to work with, and the less of a threat they pose. (Reducing oil prices also impacts people like Hugo Chavez, as a bonus.)

(Not that, realistically, Islamist fanatics pose an existential threat to the United States. They can harm us, certainly, and even cause a relatively large amount of damage, sometimes. That's not the same thing as posing a threat to the existence of the United States. For perspective, more than 30 times as many American citizens have died in traffic accidents since 9/11 than have died in 9/11, Afghanistan, and Iraq combined. Obviously I'd focus a lot more on preparedness for terrorist attacks rather than just going insane and throwing out civil liberties to try to prevent them. That'd help against natural disasters like Katrina, too.)

Escaping earth's gravity made easy: Space Elevator
Hurling big stuff up the 'well (and bringing it back): Nuclear Spacecraft

Certainly less than insurmountable, these problems.

it doesn't specifically mention the worst case (and quite possible scenario) that the fission rocket blows up somewhere in the atmosphere

Well, "quite possible" is a relative term. As noted in the article, this is a very conservative design, well below theoretical limits. With that much thrust, you can afford a bunch of extra safety measures, like the three independent scram measures listed here.

But, actually, it does address the worst case, that of all the fuel and waste getting released into the atmosphere. It's really not that bad.

it doesn't specifically mention the worst case (and quite possible scenario) that the fission rocket blows up somewhere in the atmosphere

Well, "quite possible" is a relative term. As noted in the article, this is a very conservative design, well below theoretical limits. With that much thrust, you can afford a bunch of extra safety measures, like the three independent scram measures listed here.

But, actually, it does address the worst case, that of all the fuel and waste getting released into the atmosphere. It's really not that bad.

Will lift a thousand tons to orbit in a reusable and totally non-polluting craft. (Yup, the exhaust isn't radioactive at all.) But it's "nucular", and therefore terrible. Even though we could finally launch a bunch of solar powersats and turn the U.S. into a net energy exporter...

As was pointed out elsewhere, the climber would take four months to get to geosynchronous orbit. How big of a gas tank would be required to fuel the climber for four months? How many batteries would it take? The only solutions are nuclear, solar, and powering it from the ground. Solar would only work during daylight hours and if you go nuclear, you might as well just do gas core nuclear rockets. Also, you'd get all the NIMBY naysayers protesting your climber. That leaves powering it from the ground.

Advances to what end?

to a point where its hopefully a whole lot cheaper to send stuff into space, and to a point where (like this article is about) we know exactly where to go and what to do



i can see and agree with you point
like everyone here i grew up with star trek which made space travel look easy, but the reality is space travel is expensive and dangerous

i think people of our generation and our kids can forget about space travel
unless people warm up to nuclear propulsion or find other ways of generating massive amounts energy needed to escape into orbit and beyond it will remain beyond reach of an average john doe

Do some reading in the following site. Being a nerd meens dropping preconceptions.

http://www.nuclearspace.com/

or

http://www.nuclearspace.com/a_liberty_ship.htm

It has been thought out.
If a accident in a flight pumps out in a worse case scenario a small nuke test would you be willing to fly in space the mass of 100 or a thousand conventional flights ? I can tell you burning coal pumps the highest level of radioactivity to our atmosphere. There was a time when we were setting off hundreds of times this in our atmosphere.

If after 1000 successful flights with no accident, you can then load them with thousands of tonnes of nuclear polution and actualy chuck it in the sun.

In the end we become pollution negative !!!

Don't worry, given time and a few generations this will become fact.

Giorgis

Do some reading in the following site. Being a nerd meens dropping preconceptions.

http://www.nuclearspace.com/

or

http://www.nuclearspace.com/a_liberty_ship.htm

It has been thought out.
If a accident in a flight pumps out in a worse case scenario a small nuke test would you be willing to fly in space the mass of 100 or a thousand conventional flights ? I can tell you burning coal pumps the highest level of radioactivity to our atmosphere. There was a time when we were setting off hundreds of times this in our atmosphere.

If after 1000 successful flights with no accident, you can then load them with thousands of tonnes of nuclear polution and actualy chuck it in the sun.

In the end we become pollution negative !!!

Don't worry, given time and a few generations this will become fact.

Giorgis

Yes, I said non-polluting, because the exhaust is non-radioactive hydrogen. (Read the article before denouncing, please.) For in-system work, we could use Orion or variants, or even the nuclear salt-water rocket. Those do have radioactive exhaust, but out in space that's not exactly a major problem. With that level of specific impulse along with high thrust, the costs of developing space resources are drastically reduced.

Colonies on other planets may or may not be a good idea (though with a big enough space economy a moonbase becomes attractive). But mining asteroids and putting dangerous industries in space is a very nice idea once we're not bogged down with just chemical propellants.

That craft would irradiate everything in its vicinity turning it radioactive.

And of course you posted that anonymously, because you're flat wrong. To quote from what you obviously didn't read: "Its exhaust is completely clean: It is very difficult to make hydrogen radioactive in a fission reactor. It basically can't happen." Feel free to propose a reaction based on the proposed engine that would actually do so. The craft is only dangerous if you're allergic to hydrogen.

Since the problem isn't a military one, a military solution alone will not work. Military action is certainly justified as part of the overall strategy (e.g. in Afghanistan, now sadly neglected) but can't be the only means we use. The ultimate solution is to greatly reduce our dependency on oil.

This doesn't have to involve austerity programs and such. We could go nuclear - not just nuclear power plants, but nuclear rockets - e.g. this one (the good tech stuff starts in section 7). With that, we can lift a thousand tons into orbit in a completely reusable and non-polluting craft that even eliminates not only its own nuclear waste but also waste generated on Earth. Using those, we can put up solar-power satellites that send their energy down to Earth in the form of microwaves. (If you've ever played Sim City... forget it. It doesn't work that way, it can be done very safely with large margins of safety. See here especially the section on "Safety".) With the lower launch costs of nuclear rockets, we can make the U.S. a net energy exporter, in time. This has plenty of military applications, as well. Space is the ultimate "high ground" and a dominant U.S. presence in space should have obvious strategic benefits.

Of course, at the same time we can work on more efficient techniques for utilizing the oil we do need. Cars with better mileage (improving our overall fuel efficiency by less than 3mpg would eliminate our need to import oil from the Persian Gulf), more efficient means of generating and using fertilizers, a bit of thought about how we use plastics, etc. Even better, we can sell the technology we develop to other parts of the world - further reducing world demand for oil, driving the price down. The lower the price of oil, the less funds the Islamist fanatics have to work with, and the less of a threat they pose. (Reducing oil prices also impacts people like Hugo Chavez, as a bonus.)

(Not that, realistically, Islamist fanatics pose an existential threat to the United States. They can harm us, certainly, and even cause a relatively large amount of damage, sometimes. That's not the same thing as posing a threat to the existence of the United States. For perspective, more than 30 times as many American citizens have died in traffic accidents since 9/11 than have died in 9/11, Afghanistan, and Iraq combined.)

I'm happy to hear that the crew is not in serious danger, but it's still past time that we replace the shuttle, which was a poor compromise from the start, with something SnApPiEr.

Kill for fun and profit?

Who needs Ion propulsion. If we redevelope the courage to explore the solar system, the technology to use Nuclear Thermal Rocket propulsion has been around since the 1960s. Read Opening the Next Frontier at

If there were demand for it, one could imagine that something like the Sea Dragon (which would have lift capacity of ~550 metric tons to LEO compared to ~25 metric tons for a Delta 4 Heavy) could be mass-produced.

Oh, don't be a wimp. How about this puppy which can lift 1,000 tons to orbit, is fully reusable, and has totally non-polluting exhaust! (Unless you're allergic to helium or something...)

It becomes a lot less expensive if there's a cheaper way to get stuff to orbit. Something like this.

NuclearSpace.com has an interesting series about nuclear powered rockets.
This installment details a hypothetical design for a non-polluting, 100% reusable nuclear rocket based on the Saturn V form factor, that would be able to lift 2 million pounds of cargo into Earth orbit and return to a powered landing. With payload weight no longer an issue, such a vehicle could power a point-and-shoot mission to Mars and back in less than a year, hauling an incredible amount of equipment and supplies and returning with hundreds of tons of Martian samples.

This one for liftoff from Earth (exhaust is not radioactive), and in-system work, and this one for deep-space missions. We can move thousands of tons around with these, cheaply and safely. (Note: neither of these is an Orion type, which is another option.)

Might we not make single-stage-to-orbit vehicles which so drastically reduce the price of launch costs that building a space elevator is not only possible, but unnecessary?

The problem with rockets has never been the mass of the rocket, but the mass of the fuel. There's only so much oomph you can get out of a million litres of hydrogen and oxygen chemically, and it's only marginally more than the power it takes to lift a million litres off the surface and into space. Sure, a lighter fuel tank, and lighter payload will help, but not significantly.

No, if we want cheap access to space, we either go nuclear, or build some sort of space elevator. While we may just be at the threshold of being able to make materials with the tensile strength needed for a beanstalk, we have the tech to make gas core nuclear rockets right now.

What you are talking about here are collisions of culture, which you are conflating with the idea that morals are absolute - which they certainly are not. In the past, when a severe collision occurred, the survivor's answer was to fight until only one culture survives. The Islamists still understand this, but the (quite different) morals of the west reject the idea of putting down an entire culture, even though that culture is polarizing against them in the most obvious manner possible, and has no such scruples. The answer that beckons with survival as the prize - from history - is clear and obvious (and it is the same answer the Islamists have come to.)

Except the "Islamists" can't threaten the survival of our culture.

They can't field a competent army, and Islamic culture also produces second-rate science. Their whole social system bears more than a passing resemblance to feudalism. The only thing that supports it is the reserves of oil there. Their economies can't be productive (or stable) any other way.

Terrorists are not an existential threat to the "West". They can cause harm, occasionally a lot of it. But they do not threaten our culture's existence in the slightest.

Personally, I think the obvious choice is to spend billions on working out economical technology that doesn't involve depending on oil (as opposed to, say, military adventurism, which doesn't change the long-term picture at all - at least, for the better). If we weren't dependent on the oil, we wouldn't have to care what they think. (For better or worse, humanitarian crises in Africa don't affect pocketbooks elsewhere, for example.) If we cut our consumption, and sold products and technology that cut worldwide demand for oil, the price would drop and the "Islamists" would face a funding crisis.

Pretty straightforward, really. Get over the stupid aversion to nuclear power (which can be made safe) and we gain a lot more interesting advantages - like serious exploration of space, (no, that's not an Orion, no fallout at all), which leads to orbital power generation, etc.

You could always use on of these puppies. http://www.nuclearspace.com/a_liberty_ship10.htm Sure they would be an environmentalists nightmare, but hey 1000tons to Leo is too good of a deal to pass up.

Gas core nuclear reaction rockets can be up to an order of magnitude more powerful than the best chemical rockets. It is possible to build a rocket that could put thousands of tons into LEO per launch, or an order of magnitude more cargo than a SaturnV, reusably.

As for a tail first landing, that is the best way to go when landing on airless, or nearly airless targets such as the Moon, or Mars. Not only do you not have to worry about atmosphere density or maintaining flight speeds (how many runways are there on Mars?), but once you're down, you're already set up for re-launch.

I was more thinking something like this:
http://www.nuclearspace.com/a_liberty_ship.htm

Than Orion or Nerva.

The only real problem (none political) would be if something went wrong. But why not launch that from a floating platform in the pacific - no noticable harm then, let it compete head to head with the space elevator next to it :-)

This is assuming we can ignore politics though, which you're quite right just isn't fair to do. Still if the day comes when 90% of our electric comes from nuclear, would people still be as opposed to nuclear rockets then?
This is of course assuming we can't get fusion to work in the same way we currently can't get CNT to work...

And as another poster pointed out, if we can make CNTs work well enough to make a space elevator, won't that take conventional launch vehicles into a new realm too (imagine them much lighter and stronger)

I dunno about that. And this one, while nuclear, is non-polluting!

In 1800's the Chinese started building a giant stepladder to reach the Moon. While some said they should wait for a better technology, the Emperor decided to sink the country's resources into the 'project' anyways "because the country needed to evolve modern stepladders if we're to reach Mars, if we're to populate the solar system, and if we're one day to go out among the stars"

I hope this litte joke illustrates the problem with what you are proposing.

Joke? What Joke? This sounds just like an idea that has been talked about for 40 years. Only instead of a steplader, it's called a Space Elevator

As for the ION engines you talk about. The problem with them is they provide very little thrust at any given time. A nuclear engine version would be much more practical.

No kidding??? You've got to be kidding!

The original Orion engine design specified detonating ONE BOMB PER SECOND. Making it feasible to manufacture tiny atomic bombs in the quantities required would be an industrial feat to rival anything ever done by mankind. For two weeks of acceleration the engine would consume over a million bombs. As others have pointed out, the ship itself would be enormous, and the bombs would have to be ferried up to it with numerous orbital flights. Every single mission would be a stupendous undertaking. I can't believe anybody still takes this concept seriously.

A much more practical way to build a nuclear engine would be to use a gaseous core reactor to vaporize a nonradioactive propellant. For example, here is an article about a hypothetical design for a fully reusable nuclear rocket based on the Saturn V form factor, that would take off from the ground and haul 1000 tons of cargo into orbit, and could return an equal size cargo to a powered landing. A rocket with such carrying capacity could make interplanetary flights directly from Earth, with no need to manufacture, store and transport millions of atomic bombs.

The defeating feature of this type of vehicle is that it must carry its entire fuel load for landing as well as lifting off. The space shuttle works around the issue by dropping much of its physical structure on ascent, and gliding back with virtually no fuel. Nuclear rocket engines would completely eliminate this issue because of their much higher Specific Impulse, which is basically a measurement of thrust combined with how long that thrust can be maintained by consuming a given amount of fuel. Take a look at this article (part of a longer series) about a design for a non-polluting, fully reusable nuclear rocket based on the Saturn V form factor, that could lift 1000 tons of payload into orbit and return an equal payload to a powered landing (compare vs the shuttle's 32-ton capacity). Just like the Delta-X rockets, only practical because of the enormous power of the nuclear engines.

Nuclear powered rockets would make all this consternation over supplies irrelevant. A decent nuclear rocket could haul hundreds of tons of supplies in a single mission. Here is a great article about a hypothetical design for a 100% reusable nuclear rocket based on the Saturn V form factor, that could not only lift 1000 tons of payload into Earth orbit (for comparison, the Space Shuttle can handle 32-tons), but also return an equal size cargo to a powered landing. Such a ship could haul enough food, water, air and equipment to the moon in one flight to keep a lunar colony going for several years, not to mention returning with an unprecedented quantity of lunar samples. No disposable fuel tank, no retrieving boosters from the ocean, no tiles falling off, just a big single-stage rocket doing an old fashioned Buck Rogers takeoff and tail-down landing.

Now let's talk Mars. Because of their enormous load-carrying capacity, nuclear rockets would be able to haul double-hulled interplanetary ships jacketed with a full foot of water, and get there in less than 3 months. The short transit time would decrease the crew's radiation exposure. The water would provide radiation shielding as well as self-sealing micrometeorite protection. (The outer few inches would freeze, and if a micrometeorite punctured the hull the leak would instantly refreeze and seal the hole.) The water/ice jacket would also function as a passive cooling system, eliminating one more major system. If only NASA would put serious money into building nuclear engines instead of into workarounds for the problems that they would solve.

Good time to slip in a plug for Gaseous Core Nuclear Reactor rockets, especially the clean-burning "nuclear lightbulb" type. Basically it is a quartz bulb containing a cloud of uranium hexafluoride gas, confined in the center by a swirling cloud of a lighter buffer gas, which insulates it from the quartz and controls criticality. The uranium gas heats up to 25000C and emits intense ultraviolet through the quartz. Liquid hydrogen pumped over the outer surface of the bulb absorbs the UV, vaporizes and shoots out of the rocket nozzle. The nuclides are sealed in the bulb and the hydrogen exhaust is not radioactive. An engine of this type would have many times the lifting capability of any chemical engine possible.

Here is an article that discusses a hypothetical design for a fully reusable GCNR rocket based on the Saturn V form factor, that could lift 1000 tons of payload into Earth orbit (compared to the shuttle's 32-ton capacity) and return an equal amount of cargo to a powered landing. Nuclear rockets like this could make significant manned missions to Mars possible, drastically reducing the travel time and carrying huge amounts of supplies, equipment and radiation shielding.

Hmmm...Project Orion...he's so dreamy...

*rolls eyes*

You do know that Wernher Von Braun went along with the plan to launch an Orion on the Saturn V, right?

Von Braun was intially skeptical of the Orion design, thinking it to be a fanciful idea. However, after he witnessed the Putt-Putt test, Von Braun changed his tune. He was still enamored with his chemical rockets for liftoff, but he began to envision the Orion being used as interplanetary transportation. Thus the Mini Orion was born. If things had gone as planned, the Orion would have been the space transport of the future. Sadly, the Saturn V program was shut down before the plan could be fully executed, and Von Braun resigned in disgust.

The RTGs in question here are not just Plutonium slugs.

Remember there have been accidents with them in the past.

During the three mission accidents that did occur, the RTGs performed as predicted. The Transit 5-BN-3 mission was aborted because of launch vehicle failure. The RTG burned up on reentry as designed with the plutonium dispersed in the upper atmosphere. The RTG design was changed shortly after that to accommodate intact reentry. The next accident was with the Nimbus-B-1 that was aborted shortly after launch by a range safety destruct. The RTG was recovered, with no release of plutonium, and the heat sources were reused in later missions

The failure of the Apollo 13 mission meant that the Lunar Module reentered the atmosphere carrying an RTG and burnt up over Fiji. The RTG itself survived reentry of the Earth's atmosphere intact, plunging into the Tonga trench in the Pacific Ocean. The US Department of Energy has conducted seawater tests and determined that the graphite casing, which was designed to withstand reentry, is stable and no release of plutonium will occur. Subsequent investigations have found no increase in the natural background radiation in the area.

In order to minimise the risk of the radioactive material being released, the fuel is stored in individual modular units with their own heat shielding. They are surrounded by a layer of iridium metal and encased in high-strength graphite blocks. These two materials are corrosion- and heat-resistant. Surrouding the graphic blocks is an aeroshell, designed to protect the entire assembly against the heat of reentering the earth's atmosphere. The plutonium fuel is also stored in a ceramic form that is heat-resistant, minimising the risk of vaporization and aerosolization. The ceramic is also highly insoluble.

http://en.wikipedia.org/wiki/RTG
http://www.ne.doe.gov/space/space-desc.html
http://www.nuclearspace.com/facts_about_rtg.htm

http://www.bellona.no/en/international/russia/navy /northern_fleet/incidents/31772.html
Nice information about RTG powered lighthouses

I can't stand people that are ignorant enough to protest anything with the word "nuclear" attached to it. Blind ignorance is all that is. They don't even have the most basic understanding of what they are protetsting

Of the fifty odd launches of reactors or RTG's - no fewer than nine have resulted in the radioactive material being returned to earth. This article lists eight failures, but misses a ninth. It's not a pretty record - and it's only by luck that major contamination has been avoided.

Lemmings.

IIRC some of the solid core nuclear thermal rocket designs were supposed to have good enough thrust to weight ratios to escape Earth's gravity under their own power (e.g. DUMBO).

Is this the report you're thinking of? DUMBO was indeed a paper design intended to show that the engines could be lighter and more powerful. Even so, I don't think the design was ever sufficient to reach orbit. Project Timberwind continued the work for the StarWars project and had a thrust to weight of 30:1. In comparison, the Space Shuttle Main Engines have a 73:1 thrust ratio and they still need assistance from the higher thrust SRBs. (The SRBs provide 71.4% of the Space Shuttle's thrust during liftoff, each providing 3,300,000 lbf vs. the 400,000 lbf each SSME generates.)

The only reliable way to overcome the thrust-to-weight problems that plague the NTR engines is to run the reactor so hot it melts the uranium fuel. As you can imagine, anything that can melt Uranium can melt most materials we have available. The solution to this problem is the Gas Core Nuclear Rocket which relies on the "nuclear lightbulb" concept to keep the reactor gasses from interacting with the walls of the engine. I've spoken with a former NASA Nuclear Propulsion engineer on the issue, however, and he's very concerned about whether the concept is feasible or not. It seems that there's a lot of research that still needs to be done on the subject. It's a wonderful dream, however. :-)

Besides those, you have nuclear pulse propulsion (e.g. Orion), which most definitively would have a good enough thrust to weight ratio.

I do believe we were talking about NTR engines, but Orion can certainly attain orbit. The only problem (which is also one of the reasons why the Orion was never built) is that the Nuclear Test Ban Treaty of 1963 made it illegal to launch an Orion from inside the atmosphere. This relegates it to being a space-only engine, and/or a useful craft for Moon or Mars launches.

Ok, forget chemical rockets. Here is an interesting article about a 100% reusable nuclear rocket design based on the Saturn V form factor, capable of launching 1000 tons of payload into Earth orbit (30x the space shuttle's capacity) and returning an equal size cargo to a soft landing. No exploding atomic bombs (I never could take the Orion concept seriously myself). This design involves a "nuclear lightbulb" engine, consisting of a quartz bulb containing a cloud of gaseous uranium that emits intense energy in the ultraviolet range. Liquid hydrogen flowing over the outside of the bulb absorbs the UV without becoming radioactive, superheats and shoots out of the rocket nozzle.

Like this.

I agree. There was so much work done on this in the 60s that took us so close to being able to put people into space. We could have Carnival Cruise line class ships if we wanted. 2001: A Space Odyssey would not have been all that far off if we hadn't lost our nerva.
http://nuclearspace.com/

Sure, this whole CEV and heavy lift rocket for large payloads thing makes sense... 25 years ago.

The only really innovative space ideas are what people like scaled composites are doing (spaceship one and soon two).

Nasa should be doing what only they could do: nuclear (because I dont think any independant company is going to be allowed to do it). A nuclear rocket would be completely reusable, more reliable, safer (especialy on re-entry), and probably cheaper.

Sadly, all the anti-nuclear idiots would probably never let it happen. They can barely contain themselves when we launch a little tiny space probe with a little tiny nuculear engine on it..

Scratch the subject up there.. make it, "People suck"..

Preach to the choir much? ;-)

Sadly, after talking with some engineers I have doubts that the Liberty Ship could ever exist. Apparently the nuclear lightbulb concept has never been tested. It sounds great in theory, but the engineering problems it entails may be insurmountable with current tech. As a result, we'll just have to settle for an engine like the TRITON for now. Same Mars performance, but a bit tricker for the liftoff.