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These days, "people" (meaning "people in general" not "the people I know") couldn't care less about science unless it affects them directly, and even then they are only interested in the effect (especially if it's frightening), not in the science. Science programming that isn't announcing an asteroid heading toward the Earth has to be watered down to pure amusement level or only geeks will watch it. That's why cars, motorcycles and home remodeling dominate Discovery Channel and TLC now.

Anyway, since you mentioned nuclear propulsion and the Saturn V, here is a long and fascinating article about a nuclear powered rocket the size of a Saturn V. Fully reusable and emitting no radiation, it would lift 1000 tons of payload into Earth orbit and return with 1000 tons of cargo to a powered landing. If they made a show about that, it would have to focus on the rocket's potential to haul up entire space hotels and recreational facilities.

Nuclear rockets would completely solve the supply problem for orbital stations. Before you knee-jerk on the word "nuclear" read this fascinating engineering scheme for a fully reusable Saturn-V size nuclear rocket, using a Gas Core Nuclear Reactor (GCNR) engine. It's a 12-part article, but skip the first 6 sections if you just want to know how it works. Briefly, gaseous nuclear fuel encapsulated in a light-bulb-like quartz vessel heats up to about 25,000 degrees C, emitting intense ultraviolet light that heats hydrogen flowing around the outside of the bulb. The superheated, non-radioactive hydrogen then jets out of the rocket nozzle. The nuclear fuel stays confined and nothing ever touches it.

Such a rocket could lift 2 million pounds of payload into low orbit (compared to the Shuttle's 60,000 pound capacity) and return with 2 million pounds of cargo to a powered landing rather than an unpowered glide. There is very little information about this technology on the web, but I believe the big aerospace firms are looking into GCNR as the heavy lift engine of the future.

Check out this fascinating detailed design for a completely reusable Saturn-V size rocket, powered by a Gas Core Nuclear Reactor engine. The engine emits non-radioactive hydrogen propellant. The rocket described would be able to lift 1000 tons of cargo into orbit and return to a powered landing, for only 5% of today's cost per pound.

I know "nuclear" is still a dirty word, but the gas core reactor design is a completely different approach than a big pile of plutonium. Very promising in terms of power, safety and cost.

It's a long article, 14 parts, but well worth reading. Skip the first 5 or 6 sections if you just want to know how the thing works.

Check out this excellent article about Gas Core Nuclear Reactor (GCNR) rocket technology. A GCNR rocket would be fully reusable and would emit no nuclear waste -- only superheated, non-radioactive hydrogen. The multi-engined rocket could be designed to vent its own spent nuclear fuel during its orbit circularization burn, a routine maneuver that changes the flight path from parabolic to circular. The exhaust, travelling at 30km/sec, would escape the Earth's gravity and could easily be aimed to hit the sun. The two million pound payload capacity of such a rocket (not gross weight or fuel, payload weight) would make it highly feasible to haul up a few hundred pounds of earthbound nuclear waste per trip as incidental cargo and inject it into the exhaust.

Even if you don't believe in this particular approach (or don't want to bother to learn about it, so you have no meaningful opinion), does it really seem likely that the human race will continue to have a problem getting things off the planet for the next two hundred thousand years??? I find it ludicrous that people have spent so much time and energy dreaming up ground-based facilities to last that long.

At best any ultra-long-term ground storage plans are incredibly pessimistic, presuming that some natural or man-made global tragedy will prevent the evolution of practical, large-scale space flight. We're so close.

The smallest feasible Mars expedition requires 150 or so tons in Earth orbit, which takes 5 trips on the most powerful rocket flying today, the Space Shuttle. A large nuclear powered booster could put six times that mass in orbit in one flight. According to this article, an Apollo size rocket with gas core engines would be safe, economical and would even get rid of excess nuclear waste.

This is not new. NASA tested Nuke engines in the 60's. If we are serious about going to Mars, we have to start building nuke engines.

The smallest feasible Mars expedition requires 150 or so tons in Earth orbit, which takes 5 trips on the most powerful rocket flying today, the Space Shuttle. A large nuclear powered booster could put six times that mass in orbit in one flight. According to this article, an Apollo size rocket with gas core engines would be safe, economical and would even get rid of excess nuclear waste.

This is not new. NASA tested Nuke engines in the 60's. If we are serious about going to Mars, we have to start building nuke engines.

The smallest feasible Mars expedition requires 150 or so tons in Earth orbit, which takes 5 trips on the most powerful rocket flying today, the Space Shuttle. A large nuclear powered booster could put six times that mass in orbit in one flight. According to this article, an Apollo size rocket with gas core engines would be safe, economical and would even get rid of excess nuclear waste.

This is not new. NASA tested Nuke engines in the 60's. If we are serious about going to Mars, we have to start building nuke engines.

There is another existing technology that could travel interstellar distances. NASA's Orion project designed a starship propelled by nuclear weapons and a big pusher plate. And yes, the crew can be properly shielded.

Of course what we really should be working on is actual nuclear rockets - controlled nuclear burn instead of explosives. Nuclear gas core rockets are really not beyond present technology, their exhaust is cleaner than the space shuttle's, and they're so powerful you can build big, heavy, safe vehicles.

Thanks! I found that NERVA is also an acronym for Nuclear Engine for Rocket Vehicle Application , as well as being a Roman Emperor.

Living in Japan, I guess I sometimes feel a little disempowered when it comes to looking things up for some reason. Must work on that... ;-)

Here's another good link about nuclear engines for space, by the way.

This is as good a place as any to remind people of the potential of reusable rockets based on Gaseous Core Nuclear Reactors, which could make possible a Mars mission of about 9 months, not 3 years. I highly recommend reading this fascinating detail design for a fully reusable rocket based on the Saturn-V form factor, that could launch a 2 MILLION pound payload and return intact to a powered landing with an equal size payload.

Essentially, the rocket engine consists of a chamber containing a transparent quartz bulb, which contains a core cloud of UF4 gas surrounded by a swirling buffer gas that controls the shape and size of the UF4 core. The core heats to about 30,000 C, emitting intense ultraviolet light that heats hydrogen gas flowing past the bulb. The hydrogen, absorbing the ultraviolet but no neutrons, superheats and shoots out through the rocket nozzle, providing many times the thrust possible with any chemical rocket, and without radioactivity.

One issue the NuclearSpace.com article addresses that is rarely discussed is the need for radiation shielding during interplanetary travel. So far, humans have barely ventured beyond the Earth's protective magnetic field. Prolonged exposure to the solar wind would take a heavy toll on Mars astronauts during a 3-year mission. With a GCNR rocket the round-trip travel time would total only 6 months. The enormous payload capacity would allow for extremely heavy radiation and particle shielding, not to mention ample supplies and equipment for a comfortable, productive stay.

This technology really excites me -- the potential for spaceships that are roomy and well equipped, even luxuriously so, and well shielded from the real-life hazards of space travel. Sign me up!

This is as good a place as any to remind people of the potential of reusable rockets based on Gaseous Core Nuclear Reactors, which could make possible a Mars mission of about 9 months, not 3 years. I highly recommend reading this fascinating detail design for a fully reusable rocket based on the Saturn-V form factor, that could launch a 2 MILLION pound payload and return intact to a powered landing with an equal size payload.

Essentially, the rocket engine consists of a chamber containing a transparent quartz bulb, which contains a core cloud of UF4 gas surrounded by a swirling buffer gas that controls the shape and size of the UF4 core. The core heats to about 30,000 C, emitting intense ultraviolet light that heats hydrogen gas flowing past the bulb. The hydrogen, absorbing the ultraviolet but no neutrons, superheats and shoots out through the rocket nozzle, providing many times the thrust possible with any chemical rocket, and without radioactivity.

One issue the NuclearSpace.com article addresses that is rarely discussed is the need for radiation shielding during interplanetary travel. So far, humans have barely ventured beyond the Earth's protective magnetic field. Prolonged exposure to the solar wind would take a heavy toll on Mars astronauts during a 3-year mission. With a GCNR rocket the round-trip travel time would total only 6 months. The enormous payload capacity would allow for extremely heavy radiation and particle shielding, not to mention ample supplies and equipment for a comfortable, productive stay.

This technology really excites me -- the potential for spaceships that are roomy and well equipped, even luxuriously so, and well shielded from the real-life hazards of space travel. Sign me up!

A) This was still a test reactor. Not one that was made to go mainstream.

B) A careful examination of the remains of the core and the vessel concluded that the control rod was manually withdrawn...

This tells me that someone had to physcally be an idiot, not that something had to break or malfunction.

In spite of this 'negative publicity', I still strongly support nuclear power. You aint the only one. Support Nuclear Power, and Nuclear Space

A) not sure a space station could be moved intact from earth to orbit. Would probably have to be moved in pieces.

B) HEAVY LIFTER RIGHT HERE Liberty Ship How is a 1000 Ton payload for ya? And yes, that is the correct figure.

But manned space flight is incredibly expensive in comparison

That is because we use Chemical rockets. If we use nuclear rockets as posted in a previous slashdot story Nuclear Space.com we can do it for less. And we have made a nuclear reactor that can survive blowing up on a launch pad, and one that did it too. So we don't have to worry about radiation fall out. Besides, there is only so much a robot can do. And, we can get resources from space to earth. Want 100 billion tons of nickle or Iron anyone?

And just think about when (NOT IF) we get a space elevator up, the cost of getting to orbit will plunge.

Dude, you are so confused it isn't even funny. The early experiments in nuclear propulsion for flight were done by a company that basically loaded a reactor on board, flew it around, took some radiation readings, then proclaimed that nuclear flight needs "men over birthing age". (A really stupid statement if I ever heard one.)

After that, Project Pluto was commissioned as a nuclear bomber. Since the point was maximum destruction to the target area, the reactor was completely unshielded. It would still drop its bombs, but its unshielded nature would be great for added death and destruction. And since it used air and nuclear fission for fuel, they could fly it around enemy territory for months after the bombs were dropped. The project was dropped after ICBMs were shown to be a better near term solution. There weren't a whole lot of tears shed either, since many considered the project's goals a bit sadistic.

In the 60's, serious uses for nuclear propulsion were considered. The two that received the most funding and research were Orion (which had a built in radiation shield by the nature of its design) and NERVA (which was looked at for the upper stages of a moon mission, where the thrust to weight ratio didn't matter quite as much). While both were tested in a reasonable and safe manner, neither actually flew. The reason was that chemical propulsion was already more advanced and would be ready sooner than nuclear solutions. Thus the Saturn V was built for the moon mission.

After the Saturn V was finished, Von Braun began looking forward to exploring the rest of space. He was shown the "joyrider" experiment (a coffee can sized Orion that used conventional explosives) and became a believer. It was his intention to launch an Orion into LEO on top of a Saturn V. Once in space, the Orion could use its nuclear pulse drive to cruise the solar system.

Unfortunately, the US government had other plans. Since the Russians were defeated in the moon race, the US made quiet plans to decommission our remaining arsenal of super-rockets. The space program was scaled back to only handle comsat and military launches. Von Braun strongly disagreed with the government over this point, and eventually left to found the National Space Institute (later the National Space Society). Sadly, he contracted cancer and died in 1977. And that pretty much ended the golden age of space exploration.

The end result is that we have more designs for nuclear propulsion than we know what to do with. Yet not one of those designs has ever been flown, or will be flown, until someone says, "let's go explore!"

Most people just don't realize that we do have the technology to travel the solar system. "We can barely get to LEO!" they say. Too bad no one told them what we actually have to put in LEO. Space travelers live and die by the amount of energy they have available. Nuclear fission provides plenty.

BTW, check out the multimedia section over at Nuclear Space. They have the footage of the Orion joyrider, and the NERVA engine tests.

My first choice would be for a space elevator, but if we want to get to Mars without it we should go nuclear

Can NASA put 7,700 tons into orbit?


Short of an Orion, the largest proposal I've seen is 3,000 tons. And part of that is rocket engine weight. If you launched multiple times and constructed it in space, it could be doable. (i.e. The hull in one launch, the reactor and some internals in the next, and the weapon systems and the rest of the internals in the last.)


Can a Seawolf deal with re-entry heats?


If you're going to launch something that big, I think you'd keep it up there. Not much point in a large reentry craft.

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Well your argument is good to explain a possiblity of dying from immediate exposure but what about long-term carcinogenic and other health risks.

Here's what most people don't realize: If you don't get cancer from radiation within a few months, it probably isn't the radiation! Your body is quite used to radiation. The Sun is spewing it out every day. While the Earth's radiation belts stop most of it, there's a significant amount of radiation that hits the Earth. (If there was none, the Earth would get pretty cold.)

Much of that radiation that passes through humans actually misses entirely. i.e. It passes through your body without hitting anything. Of course, some of it does strike. Alpha and Beta particles will simply bounce off your skin. Gamma and Xray radiation is what will usually penetrate. Most of the radiation will collide with something unimportant (e.g. water) But a small remainder may be lucky enough to hit your DNA.

When your body is healthy, it will usually notice the errors in the DNA and correct them. Otherwise you'd get cancer before you were even born! However, if you are lacking certain enzymes, or too many DNA molecules have been changed (as would happen if you were exposed to say 1000+ REM) then you may get cancer.

Now, radiation damage does take your body time to repair. As a result, you should be careful about constant exposure to high radiation. Constantly exposing yourself would cause more damage before your body is finished fixing the old damage.

And that is why radiation early in life won't kill you later in life. If you get cancer at a later date, it probably is from all the radioactive uranium put out by Coal plants. Alternatively, you may have too many radioisotope particles in your system. There's a relatively high amount of Sr-90 and other radioisotopes in the environment from nuclear bomb testing. Or perhaps your cancer has nothing to do with radiation at all, and is instead caused by an error in your body while transcribing your DNA.

For a guy so well educated in the technology you surely have funny concept of human psychology. Lemme translate your statement for you this way:

Your little story is why Failure Is Not An Option(TM). NASA launches toward the ocean so that anything that blows up doesn't land on populated areas (wind or no). My comments are not meant to make people feel better if rocket ships do land on their home (although it would be nice if they did feel better), but rather make them feel better about nuclear technology in the here and now.

On another note the GNCR concept escapes me, it looks like the propellant is injected into a swirl of super hot uranium gas and then ejected along with portions of the gas via the venturi... isnt this producing a continuous stream of radioactive material out the back of the rocket?

If you look at the picture, you'll notice that the uranium plasma is kept in those middle oval areas, while the hydrogen in pumped around them in the outer tubes. Basically, the hydrogen will loop around the core once or twice, and become plasma on the way. By the time it reaches the exhaust, the hydrogen is as energetic as it's going to get.

Now, how do they manage containment? Well, they actually use something called a "nuclear light bulb". Instead of explaining what that is, I'm going to direct you here:

http://www.nuclearspace.com/a_liberty_ship7.htm

Make sure you read the next page as well. That's where the nuclear light bulb itself is explained. You might even want to read the whole article. It's a fascinating look at how nuclear propulsion can change space travel forever. :-)

P.S. I see that the evil Offtopic/Underrated mods have shown up. All my recent posts have suddenly been modded down, even though they're no longer on the front page. I wonder when they'll figure out that trying to reduce my Karma with abusive moderation is pointless.

Do you know how much more that would increase the mass of the space craft?

Yes. Does 6 million pounds sound large enough for you? How about 8 million tons? It's possible to launch 6 million pounds with a GCNR craft. Once in LEO, the same engines can give even better performance (since they don't have to work against air resistance). Orion (this needs quite a bit of development) could give us an 8 million TON craft for space travel. Even if you go with NERVA, you have 2-4 times the thrust of today's engines. GCNR gives you 6-20 times the thrust.

How about the fact that the g forces created when accelerating to approx 20,000 kph would KILL any humans on board? Robot don't have that problem, so they can get there much faster!

Let's say we accelerate at the speed of 5g's. Let's do the math...

Why on Earth (sorry, space) would you want to accelerate at 5Gs? Constant acceleration at 1/4 G would be sufficient to get to Mars in months. No need to light off a firecracker under your ass.

No, nuclear propulsion is NOWHERE NEAR sophisticated enough to do this, why do you think they use HYDROGEN!?

This makes no sense. They use Hydrogen because it's a very common gas, with a lot of energy to expend. GCNR and NERVA can actually use quite a few other types of fuels (e.g. oxygen, xenon, nitrogen, etc.). There's research going on to find which fuel is the most efficient.

The more exotic propulsions don't even bother with hydrogen. Nuclear Salt Rockets use a Uranium salt water solution as propellant. Orion uses atomic bombs. (Okay, so if they used H-Bombs, they would have to use some hydrogen.)

What do you think happens in a rocket? Perfect sailing? You think a reactor will run perfectly fine while it's being shaken around by acceleration and turbulance?

Are we talking launch or space travel? In the former, the reactor is going to have to be built to withstand vibrations. This is nothing new. Carriers and submarines already have to take precautions against the reactors being shaken. In the later, there's no vibration, because there's no turbulence. No air, remember? And the engines are a bit more sophisticated. The gases are heated until they become plasma, then are exhausted out the rear at a high velocity. Most of the plasma will stay in containment, so there really isn't much vibration produced by this method.
(I'm assuming GCNR or NERVA. Orion and Nuclear Salt will vibrate plenty, but they have no reactors to speak of.)

SPINNING craft? How much larger do you want them?

I'll take "6 million pounds or larger" for 300, Alex.

With current technology it is NOT POSSIBLE to SAFELY send people to Mars. It'll be done soon enough (10-15 years perhaps) but right now, you are very wrong.

Anyone who's done the research, knows that we have the technology. The greatest thing holding us back, is the fear of nuclear power. There's no other method to produce megawatts of power from tens of pounds of fuel. Nuclear can do it, we just have to embrace it.

We have the engines to make it possible. What more do you want?

finding out how to send people on a 6 month trip in 0 G

Nuclear rockets can power a large enough craft to spin. Or alternatively, some engines could produce light gravity via constant acceleration.

finding a rocket ship with enough lift capacity

Found it. GCNR technology is mostly developed. NERVA technology already is developed.

bringing enough food/supplies for multilple weeks/months,

That's actually the least of our problems. We've had a lot of experience with long missions thanks to submarines and carriers.

creating a suitable living environment etc

Probes can't solve this. Engineers can. Mars has *some* atomosphere to where we can build shelters. Something like a strong tarp to make a livable "balloon" would be an example solution.

All this time has passed, and we still can't think of a more efficient heavy launch vehicle?

Sure we can. It will just get clasified as "evil" by those who oppose high energy. We already have the technology. We just need to use it.

Spewing radiation all over hell and gone is a predictable reaction from the government types of course.

They'll probably be able to string the younger naive techies along for a while -- but really -- who do they think they're fooling anymore when the Congress votes overwhelmingly to import H-1b employees during an unemployment crisis and against the will of 86% of the voting public? They hate their technologists due to the fear that they will discover who really has the real power over technological civilization. Yhey just don't have any good way to extracate themselves from their responsibility for what they have done to the pioneering technological culture that was The United States. It was embodied in the baby boomer generation raised to think they were going to be the vanguard of life migrating off the planet -- and relegated to doing nothing more than building the Internet so they could then be outsourced to Asia. Spew radiation all you want guys -- it won't save your asses from judgement day.

My view on it is this: Safety is important, but with all great things in life, there is risk involved. Space travel is by no means an exception to this rule.

If NASA isn't willing to take risks, then who is?

If someone doesn't do something *no progress* is going to be made. Well, at least China and Japan are putting some effort in to their space programs...

--Tim

Nuclear Thermal Rockets are the only real hope for SSTO. The challenge is doing it safely.

An interesting page is NuclearSpace.

It seems extremely conservative to me that Russia would take 30 years to get to Mars, especially considering their stated plan is to build a reactor - they'll get to Mars faster if the reactor is in fact what gets them to Mars in the first place.

The U.S. has had a working nuclear rocket engine for forty years, according to a PDF on the ROVER/Nerva project off this page. These are relatively simple engines which shoot hydrogen out the back.

Of course the reference to "already built" is bizarre, who cares if it is already built if they are going to take 30 years to do it? No reason to mention that unless maybe they are talking about tested submarine reactors.

Of course the U.S. has a deal according to this March 2003 article to get Russian nuclear rocket fuels for the nuclear rocket program of Project Prometheus through 2009.

This pdf says that using the NERVA rockets of the 1970s we could get to the moon in a day, or to Mars in 4 months. The article by a Los Alamos researcher is interesting as it talks about the social problems versus technical problems. In all it seems that the nuclear rocket costs half as much, is twice as powerful, and is safe (at least from this paper it seems that reactor core products stay in the reactor). Also from about page 21 there is an interesting section on radiation and human exploration.

It talks about using a gas core nuclear rocket (GCNR) in which we are talking about how to shield crew from radiation in flight, not on the ground, but that this will mean we can get to and from Mars in much less than NASA's planned (1998) mission of 3 years. With a specific impulse of over 3000 seconds, a GCNR ship can have a 3 month transit to Mars, 2 months on the planet, and 4 months back - thus reducing psychological stress factors by keeping the mission to 6-7 months' duration.

There is also the physical deterioration from a long flight.. Apparently the current U.S.-Russia program is aiming for even better, perhaps 2 months each way using small reactors for an unlimited fuel supply and three times better propulsion.

More info:
link
link
link
pro-nuclear space space group with more information

You should read this article called: Opening the Next Frontier. Shows, step by step how we could expand outwards into the next big frontier... Space, using nuclear powered ships.

Take a read of this article on Nuclear propulsion. Could be a solution to our slow chemical rockets. The current administration has already started the ball rolling in this.Very interesting.

Prove that a cellphone outputs 200W of "power" - ever.

Rest your digital 'phone under your CRT and see what happens when it next rings. That doesn't happen with milliwatts, o ye of the stripey and cross intelligence, not to an electron beam being pushed by maybe 40-60kV inside a lightly shielded vacuum.

The phone's official power rating is an average (as in mean, not mode or median), but the peak power is considerably higher. If your phone's average power output were 200 watts, at typical RF amplifier efficiencies you would need to feed it at least 300W, which would exhaust your batteries in an eyeblink, and burn your hand (or whatever else the device was in contact with). With a peak power ratio of 200 watts and a duty cycle of 1%, the 'phone gets to output an average of 2 watts during a recalibration cycle and yet still bounce the stuffing out of your CRT's electron beam. That's how Orion gets to use uncontrolled nukes for propulsion without smearing the crew. But there are no shock-absorbers between the 'phone antenna and your head.

Now go get a life.

Good observation. This is exactly what we hope to do for a multi-moon orbiter mission which "jumps" between the planet-sized moons of Jupiter (e.g., the proposed Jupiter Icy Moons Orbiter).

It's amazing how much radiation certain bacteria can survive, though..

By the way, NASA is thinking about a new mission to the Galilean moons, called JIMO . Very exciting stuff - it's amazing how much more you can do with a nuclear propulsion stage.

If you study the engineering behind the radiation sources that the spacecraft use you would see that the darkest of scenarios have been accounted for. Even if the launch vehicle were to explode high in the atmosphere, nothing would happen to the power supply.

Anyways, these people don't agree with you.

-T