NASA Funds Designs for a Nuclear Thermal Propulsion Rocket (space.com) 172
"Dangerous radiation. Overstuffed pantries. Cabin fever. NASA could sidestep many of the impediments to a Mars mission if they could just get there faster," writes Space.com, which reports NASA is now exploring an alternative to chemical rockets.
In August, NASA announced an $18.8-million-dollar contract with nuclear company BWXT to design fuel and a reactor suitable for nuclear thermal propulsion (NTP), a rocket technology that could jumpstart a new era of space exploration. "The strengths with NTP are the ability to do the very fast round trip [to Mars], the ability to abort even if you're 2 to 3 months into the missions, the overall architectural robustness, and also the growth potential to even more advanced systems," Michael Houts, principal investigator for the NTP project at NASA's Marshall Space Flight Center, told Space.com. NTP rockets would pull all that off by offering about twice the bang for the buck that chemical rockets do... "Nuclear thermal propulsion can enable you to get to Mars faster, on the order of twice as fast," said Vishal Patel, a researcher involved in subcontract work for BWXT at the Ultra Safe Nuclear Corp. in Los Alamos, New Mexico. "We're looking at nice 3- to 4-month transit times."
Woo hoo! (Score:1)
It's all Chode up ins! Now gimme my 1½ inches of reinforced carbon-carbon and a railgun and we'll duke it out like real space lozenges.
Fast reading is treacherous (Score:2, Funny)
For a split moment, I thought I’d just read: “Dangerous radiation. Overstuffed panties. Cabin fever.”
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Sounds like you need glasses. I wonder why.
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Put them Mickey D's up (Score:1)
That much faster with this technology.
Is there any limit to the desire of man to clutter the landscape of other lands....
So... (Score:1)
Great so now were going to pollute (Score:1)
cosmic highways with dangerous radiation. Have we not learnt anything from using fossil fuels on earth?
Then in that case... (Score:1)
.....we need to destroy every star we come across, starting with the Sun. That way we can prevent more radiation from polluting the Universe.
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Space is big. Really big. You may think its a long way to the chemist, but that's nothing to space.....Douglas Adams
Jesus guys (Score:2)
sarcasm.
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Uneducated environmentalists and like-minded Hollywood script writers have got you convinced that zero radiation is the natural state of things, and any radiation is aberrant. It's actually the other way around - radiation is everywhere. Even your own body is radioactive. The only reason the sun's radiation doesn't kill everything on Earth is because of its magnetic field,
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Even with that shielding effect of atmosphere and magnetic field, the Sun still kills a million people a year with radiation. Dangerous thing, that Sun.
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And it's not done yet, it will rise in the sky tomorrow and attack you again. Day after day, it will seek you out, it's relentless.
Buck Rogers (Score:2)
Launch the supplies already.... (Score:1)
Can we focus on the rockets we already have and simply get resources into mars orbit?
Seriously we already have the tech for supplies and it doesn't matter if the trip take 2 years. We need to get around 30 supply depots and dropships into geo orbit around mars. Stuff like simply fuel and water. Raw materials to construct 3 shelters that can last 100 years and support 200-500 people each. Large construction and mining vehicles. Point is to bootstrap mining and manufacturing on mars. It's easier to get mo
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you're overestimating how much mass we can move to Mars by conventional rockets. We can't send the ISS to Mars, our biggest rocket can send 8 tons to Mars transfer orbit. We're going to send up 57 of those to push the ISS to Mars? thousands of them for your 100 year colony's supplies.
No, we need powered fusion rockets.
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NASA Trying Something Space X Can't (Score:2)
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There's no 'push back against commercial space exploration' from NASA, they're the ones mandating programs like 'Commercial Resupply Services' and 'Commercial Crew Program' .
SpaceX officials thank NASA at every opportunity for the funding and support without which they might not have survived the early years.
If anything, more research like this is possible because commercial companies can provide the more routine services at lower costs, allowing NASA to concentrate on the science.
Rocket failure consequences..? (Score:2)
Just curious what sort of pollution or fallout we can expect if the rocket carrying this into space (or the rocket itself, if it's going up itself) has a catastrophic incident? Is the nuclear fuel in one of these things going to make a big mess as it spreads through the atmosphere and falls into the ocean?
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maybe there's a way to ship the fuel component into orbit in a basically indestructible container then install into the engine/ship in orbit.
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I sure hope so! Kinda scary there's zero discussion on this..
Combine nuclear with ion drive? (Score:1)
Re: Combine nuclear with ion drive? (Score:1)
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Yes, but if you want that much electricity, you have to have huge, heavy radiators. Nuclear thermal avoids that because the heat goes out the nozzle. The downside is that it's not as high specific impulse as lower thrust propulsion methods that deal with magnetically confined plasmas and electric power sources.
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Interestingly, with some of our most efficient solar panels, it IS possible to provide the electricity ne
en route cell damage (Score:2)
If you reduce the round-trip time for a Mars journey by one-half, does that mean only ha
Torchships At Last! (Score:1)
DVD Player (Score:2)
Finally (Score:2)
Though I will say they've got their NERVA....
Should we assume that, at the very least, they're going to start with that, rather than from scratch?
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There are a significant number of people who consider your statement that a) Mars is uninteresting and b) there's no reason to go there on par with "why should you go anywhere that you don't have cellphone coverage?"
If this is news for nerds, than you *certainly6* don't fit here. The rest of us want to see the universe in person.
Re:How does this work? (Score:5, Informative)
Re:How does this work? (Score:4, Informative)
Read up on Projext Orion [wikipedia.org] and on Aircraft Nuclear Propulsion [wikipedia.org] (both closed-loop and open-loop designs).
Extrapolate.
Profit.
Re:How does this work? (Score:5, Informative)
Re:How does this work? (Score:5, Interesting)
Project Timberwind [wikipedia.org] was a far more advanced system design than NERVA (although, unlike NERVA, they never built a prototype). The thrust-to-weight ratio of the NERVA engine was 1:1, for Timberwind it was 30:1. The notion that Timberwind is derived from NERVA does not stand up to the slightest bit of scrutiny. The designs are entirely different (other than, you know, both using a nuclear reactor and hydrogen propellant). Any new effort in this direction is likely to use Timberwind as a reference design for a jump-off point.
Re:How does this work? (Score:4, Informative)
Project Pluto [wikipedia.org] as well.
That was a crazy idea - cruise missiles that could stay airborne for months spewing radiation along the countryside.
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Re: How does this work? (Score:2)
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We're going to need some pretty major advances before we can reach even 1% of lightspeed for a craft of any significant size, thanks mainly to the exponential demands of the rocket equation. I rather suspect that comparing today's most advanced theoretical nuclear rocket designs to the first rockets to reach 10% of lightspeed will look rather like comparing an ancient aeolipile to a modern steam engine.
And we might still never see such speeds within the solar system, especially for human use. Even acceler
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Even project Orion doesn't get you to 10% of lightspeed -- there isn't that much energy in plutonium at any even slightly reasonable mass ration.
You need an efficient fusion rocket or antimatter to get a rocket up to that speed, especially if you want to stop again. More plausible are beam-rider designs where the "engine" is left at home.
Game Changer (Score:2)
Developing a nuclear reactor suitable for space flight would be a game changer, assuming it could be scaled to megawatt levels.
1. Power a magnetic shield.
2. Powering Ion drives for longer journeys
3. Of course providing all the electrical power for communications and other ship functions regardless of the distance from the sun
You get megawatts of power available and suddenly, you are talking about building a ship, not a tin can.
Re:How does this work? (Score:5, Informative)
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That said, ain't no one building anything to go into space for under 30 million. This is more like research.
Even if a prototype went into space, it'd still be research. No humans? No hurry. The Moon? Too close. A nuclear powered SLS-class launcher to Mars could be useful, but it would obviously be many years and many billions from now. And even for Mars the radiation estimate for a six months trip + surface stay with chemical rockets is within NASAs career limits, so it doesn't seem to be a requirement. And past Mars there's not really anywhere habitable for humans. I suppose it could be useful for interstellar,
Re: How does this work? (Score:3)
Nuclear thermal is particularly interesting for Venus ascent stages. It lets you do them single stage, and while you essentially have to use hydrogen, it doesn't take that much. It reduces the habitat lift requirements dramatically; while the dry mass is high, the vastly reduced propellant requirements outweigh that many times over. It aslo makes it plausible to launch to high elliptical orbits rather than LVO; this cuts the Dv requirements down on the interplanetary transfer stage significantly, meaning
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The problem is that NIMBYs will have a fit.
And when it comes to acid, plenty of metals that can deal with it.
Finally, NTRs would be perfect for the moon. Just use H2 for the fuel and O2 for breathing.
Perfect.
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Even old (let alone modern) NTR rockets had quite positive T/W ratios on Earth - let alone Venus where gravity is lower. I don't know what type of rocket you're picturing, but it's not nuclear thermal.
1) The conditions on Venus are often overstated. There's only a few to a few dozen mg per m3 H2SO4 in Venus's "habitable zone". OSHA allows workers to
Technology Readiness Level [Re:How does this work? (Score:4, Informative)
TRL 1 type stuff.
Well, the Rover and Pee Wee projects built and tested nuclear rocket engines, so it's already beyond Technology Readiness Level (TRL) 1. Right now nuclear thermal rockets are TRL 4: Module and/or subsystem validation in laboratory environment; standalone prototype implementations.
The trick was to get them to TRL 5 and beyond.
Re: Technology Readiness Level [Re:How does this w (Score:3)
Unfortunately (orrather fortunately) we'll almost certainly be sliding backwards on a a TRL perspective. There have been a lot of major improvements in NTR design since then - not just for higher peak ISPs, but in particular to deal with the poor T/W of previous designs. The first big improvement was the LOX afterburner concept, wherein you burn the hot hydrogen with LOX early in the flight fie greatly augmented thrust, then revert to pure H2. Since then a lot of designs have also called for bringing a
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That is clever adding the LOX to that, and then discard the tanks. Nice way to get up to speed quickly.
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Even if you don't discard the LOX tanks and do it as a SSTO, the mass fraction is still greatly improved versus a pure hydrogen NTR. And even in the portion of the flight where you're burning LOX with the hot H2, it's significantly higher performance than a regular hydrolox engine, because the hydrogen has already taken on a lot of energy; if I recall the numbers correctly, designs predict somewhere around 550 sec sea level.
Adding an afterburner doesn't increase the total system mass much, but greatly incre
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We can save weight by trading shielding for distance. Just use a long conductive tether to tow the reactor a km behind the main payload. The radiation will drop off as the square of the distance.
Re: How does this work? (Score:2)
That's kind of the point behind the very well thought out design of the space ship Discovery One in the film 2001: A Space Odyssey. You had a spherical pressure hull up front and a nuclear rocket in back with a long boom connecting/separating them, along with propellant tanks and other stores.
Space radiators (Score:5, Informative)
If you are going with a high specific impulse and also greater-than-micro thrust propulsion system, you will need some kind of thermodynamic cycle to generate the required electric power, and that cycle will need to reject heat. Furthermore, the heat rejection for the cold side of that cycle into vacuum involves Stefan-Boltzmann T^4 limited radiators -- the "radiator" in your aging apartment building benefits from convection of air that is not on option in space.
Even a photovoltaic cell is subject to the Carnot limit on efficiency. The solar cell has the advantage that the hot side is surface-of-the-Sun hot in terms of the radiation spectrum of the impinging light whereas you have large surface area of the panels to radiate from the cold side. However clumsy and bulky solar panels are, you will need something almost as clumsy and bulky for radiators for a nuclear energy cycle to generate electricity venturing farther out from the Sun.
Is Discovery a nuclear-electric craft? In the 2001 A Space Odyssey genre of science fiction, you still get to wave your hands a lot even though it was meant to portray a plausible near-term future rather than warp drives and Star Trek transporters. Early concepts of Discovery had large space radiators making it dragonfly-like in appearance, but that wasn't "cool" so it ended up with this thin spine with the habitat at one end and presumably the nuclear power plant way at the other end. I never did figure out what those "pods" or "bunkers" were along the spine -- too small for cryogenic propellant storage, too small for proper Stefan-Boltzman fourth-power-of-surface-temperature radiators.
There are crazy concepts for more effective space radiators involving spraying water or pellets to get enormous surface area and then somehow recapturing the water or solid pellets so you don't end up losing them. Discovery didn't seem to depict that system.
And then there is nuclear thermal, but those are much lower specific impulse, not that much better than chemical rockets, especially when you consider the bulk of liquid hydrogen tanks and the weight of the nuclear reactor. Your "radiator" (Carnot-cycle cold side) is to blast H2 molecules out your rocket nozzles, a lot of H2 molecules. We have come full circle from the NERVA project of the 60's to VASIMIR or whatever kind of much higher impulse nuclear or solar-electric propulsion back to nuclear thermal, again?
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Even a photovoltaic cell is subject to the Carnot limit on efficiency.
That is bolocks.
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And NTR is more than double the efficiency of chemical, so quite a bit better. In addition, Rei mentions the new idea of adding LOX initially to burn the super heated LH2 to provide a big k
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And NTR is more than double the efficiency of chemical, so quite a bit better.
Solid core NTR has roughly double the specific impulse of the best (practical) chemical rockets, but you lose it all in tankage for that liquid hydrogen. If you try to use something easier to store, it's going to be heavier, and your specific impulse suffers significantly.
In addition, Rei mentions the new idea of adding LOX initially to burn the super heated LH2 to provide a big kick. That actually makes sense.
I don't know if you could call that a new idea. It certainly seems a fairly obvious one, and it's one I've heard many times before. The "afterburner" running on "superheated" hydrogen really doesn't get you any more performance than a t
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Actually the original concept art for Discovery had large heat radiators; Kubrick nixed them because people would think they were aerodynamic wings.
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And if I understand nuclear reactors correctly, a lot of that mass is necessary for the thing to work, not for shielding.
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Nuclear rockets work by passing the propellant through the reactor.
Oh. I was thinking it would be like an RTG. I guess I should have RTFA.
How do you suggest we drag it behind the ship when it's the thing propelling the craft forwards?
Okay, then tether the ship a km behind the reactor.
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I thought the radiation they are talking about in the summary was from the sun.
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However, a very small shielding, combined with a truss arrangement (lined with H2 tanks, radiators) would be superior.
Re:How does this work? (Score:5, Interesting)
Almost correct. The temperatures are not actually hotter than a chemical rocket, but you can use pure hydrogen as fuel. Since hydrogen molecules are lighter than typcal exhaust gasses (water, CO2 etc), at the same temperature they are moving faster. That means you need less mass for the same velocity change in the rocket, or you can go faster on the same fuel.
The best chemical fuels are around 4500 M/s exhaust velocity. Storable chemicals are more like 3000 M/s. Nuclear thermal rockets get to around 10,000M/s So in principal you can go 2X as fast with the same fuel to mass ratio.
There are lots of caveats. The reactor is heavy. The radiation shielding is heavy - these both mean that you need a very large spacecraft before you have a net win in performance.
You probably don't want to turn one of these on before you are in orbit due to the potential problems with an accident (and the thrust to weight is pretty small anyway).
An additional problem is that its difficult to store hydrogen for long periods of time - you would need a complex and heavy refrigeration system. Or you can just use the nuclear rocket for leaving earth, and conventional storable chemicals for arrival.
Its a reasonable idea but with a lot of engineering tradeoffs that need to be considered. Its .... rocket science.
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The reactor is heavy. The radiation shielding is heavy - these both mean that you need a very large spacecraft before you have a net win in performance.
You probably don't want to turn one of these on before you are in orbit due to the potential problems with an accident (and the thrust to weight is pretty small anyway).
An additional problem is that its difficult to store hydrogen for long periods of time - you would need a complex and heavy refrigeration system. Or you can just use the nuclear rocket for leaving earth, and conventional storable chemicals for arrival.
Its a reasonable idea but with a lot of engineering tradeoffs that need to be considered. Its .... rocket science.
NERVA was heavy, but it was a primitive design. The Timberwind [wikipedia.org] reference design is not heavy, it has an impressive 30:1 thrust to weight ratio. The shielding problem is much less than you think. Until you consume nearly all of your fuel, it provides lots of shielding, and the nuclear-thermal propulsion systems are high thrust, short burn time systems. The crew would enter a small shielded shelter during the five minutes or so of the final arrival "burn". And of course, your stores (food, water) would be arr
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To put this in perspective, 30 million is 10% of the cost of an F-35 if i recall. 15x AIM-54 Phoenix missiles. a fraction of a single B2 or Aircraft carrier...
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In space, you have nothing to use. Many of the quoted nuclear projects still require carrying an exhaustible, explosive, material (eg oxygen, water, hydrogen) when the real goal of a space craft is propulsion by the nuclear reaction itself, with no other materials.
Of course you need reaction mass, so unless your design is one where the reactor fuel itself is spat out the back (NSWR, fission fragment, ...), yeah, you need reaction mass. You're not talking about nonsense reactionless drives are you? This is the real world, where we need reactions.
We are not at a stage in spaceflight that allows us to rescue a space craft. The shuttles are out of commission.
Why is the Space Shuttle required to perform a rescue operation? Actually, why would you use the Space Shuttle to perform a rescue operation? That thing only had a few hundred m/s of maneuverability once it made orbit.
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As in Robert Heinlein's book The Rolling Stones, copyright 1952
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Try Rocket Ship Galileo, 1947. That book was largely about the nuclear rocket, instead of using it as part of the plot. Heinlein did get the reaction mass wrong, planning to use the heaviest feasible atoms rather than the lightest.
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Why doesn't NASA just contract Taco Bell to supply all the inflight meals? Much cheaper and no gamma rays.
How naive you are.
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You can look these things up, Chris.
https://en.wikipedia.org/wiki/... [wikipedia.org]
Turn liquid hydrogen into lots of hot, fast gas. (Score:3)
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Someone mod this guy "funny"!
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"A nuclear powered ion-drive seems a lot more likely to work."
Indeed. Hydrogen is sort of stupid, but that is where they started decades back, and it is perhaps best if they continue along those lines and develop it properly. Then load up with Xenon and get serious. Get the Reactor nice and toasty, both heat and ionize the Xenon with it, and then work with what Plasma Physicists have been doing, in accelerating the product and shooting it out the back end. (Accelerators are notoriously thirsty, but that is
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Hydrogen has the advantage that it's available anywhere you can find frozen methane. Xenon can be a bit harder to scavenge. What I'd really like is a "high" power ion rocket that could use rocks for exhaust. This, though, is a big problem because rocks aren't a simple element, but a complex mix that varies. (By "high power" I'm thinking of about 30 pounds thrust, but that's probably dreaming.)
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You don't have to use xenon for your ion drive. [youtube.com]
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What I'd really like is a "high" power ion rocket that could use rocks for exhaust. This, though, is a big problem because rocks aren't a simple element, but a complex mix that varies. (By "high power" I'm thinking of about 30 pounds thrust, but that's probably dreaming.)
You're looking for a mass driver. You sit your rock on top of a superconducting magnet and accelerate in a large EM cannon. When it's nearly at the end you let the rock fly on and decelerate the magnet for reuse. Exhaust velocity is as high as your power supply and the length of your cannon allows. Thrust depends on rate of fire.
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No. A mass driver is a catapult based engine. I'm looking for an ion rocket based on fumes boiled out of rock, probably by a laser. Fast ejection velocity, not large amounts of ejection. I'd agree that a mass driver would probably be easier to build, but it's not at all what I was looking for.
FWIW, I'm dreaming of far ahead, with space habitats being long term living facilities that move slowly between the stars scavenging from free planets and asteroids, and moving at just enough faster than the local
Rocket engineering [Re:Nice idea but] (Score:3)
Material limits set what we can do with conventional rockets. Not just melting points but thermal shock and fatigue.
No. Chemical rockets are limited by the energy content of the chemical fuel. They haven't been limited by materials for well over fifty years.
Those material limits are the same for a nuclear power source - and shoving water through a barely sub-critical reactor to heat it seems like a laughable idea. Water is hellish corrosive at high temperatures so odds are you'd be leaving a trail of reactor guts behind you before the engine had been running long.
Nobody proposes using water as reaction mass in a nuclear thermal rocket-- Specific impulse (Isp) is not high enough; you might as well use chemical propellants.
Hydrogen isn't a lot better. See "hydrogen embrittlement"
Hydrogen is a lot better. It is pretty much what everybody (or at least, everybody who knows the technology) would use for a NTR.
Since nuclear engines were designed, built and tested [nasa.gov] with hydrogen reactio
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More to the point, the GP's comments on hydrogen embrittlement are actually rather amusing. You know the primary means to reverse the damage from hydrogen embrittlement? Annealing (heating the material to elevated temperatures). ;) It doesn't even take a very high temperature.
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Annealing temperatures aren't exactly achieved by chemical hand warmers.
Just using 'steel' as an example, steel has in the neighborhood of 20% of room temperature strength at annealing temperature (700-800C). If you have to impose a 400% safety margin, you might as well just let it get a little brittle. Especially when you think about preheaters etc and the complications of trying to get all parts that hot.
Final heat exchangers might actually be that hot or hotter, but steel as final heat exchanger?
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You do realize that we're talking about the core of a nuclear thermal rocket correct? It's not exactly a winter wonderland in there.
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Not the core, the heat exchangers running through the core.
If they are running at 700C they're going to need a different material. One that hasn't lost 80% of its strength.
The heat exchangers, as a whole, would take reaction mass from its tank temperature to its exhaust temperature.
For reference Uranium melts at about 1100C, Plutonium at about 600C.
The whole deal is a very tough materials science problem.
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You must be new around here (Score:2)
because you know what you are talking about.
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Gaseous core nuclear reactors are the future - RD-600M.
Solid core engines are too primitive. We are almost 60 years into a space age now
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Nobody seems to care about the word "nuclear submarine" or "nuclear air craft carriers.". Nuclear powered submarines are proof that a nuclear reactor can be safely operated in a small and closed system. The same type of closed system you would find a space vehicle. The technology already exists so the only thing needed is to find the most fuel source.
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You're a loony. You've probably got a cat license too.
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loony loony loony
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You've never "defeated" anyone. You're just like the proverbial pigeon playing chess, strutting around crapping on the board thinking you've won when none of your arguments have ever stood up to any scrutiny. There are places you can go to get help.
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Wow, didn't know that 4 people who profess to like your "software" constitutes "many orders of magnitude". I hope you don't program like you do math.
Also, some people like to eat human feces. Doesn't mean it's good.
Hope they bring your meds to your padded room on time today.
Cheers
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*sigh* Nope. guess your meds were late again.
Well, there's always tomorrow.
How about you provide a link to each of those comments made by the people you claim made them.
BTW, writing a text file parser is not a hard task.
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Nah, I just don't care. Keeping you busy here keeps you from posting your host spam elsewhere. Mission accomplished!
Until next time!
Re:ABOUT TIME! (Score:5, Informative)
We had this tech in the 60s. No Nukes in Space treaty killed that. An engine isn't a weapon.
No, it didn't. The Nuclear test ban treaty banned nuclear explosions in space. It didn't ban nuclear reactors, and in fact several have been flown (primarily in the old Soviet Union's RORSAT program, but one-- SNAP-10A—by the US.)
Re:NTP because... (Score:4)
Until you start up the reactor, you just have uranium fuel (half life about 1 billion years), not lots of nasty highly radioactive stuff. If it fails on launch and the fuel is not contained you only have chemical heavy metal toxicity to worry about. I expect they can do a good job of containing the fuel in any case.
Once the reactor starts up, you are safely in orbit. The biggest danger would be on return from Mars to Earth orbit. You'd certainly want to design these things not to ever attempt reentry. It would take a lot going wrong to cause accidental reentry.
I'd want there to be a high quality risk assessment, but I think it wouldn't be hard to reduce the risk of atmospheric contamination to very low levels.
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The one plan I ever saw for nuclear thermal (a paper by Von Braun outlining a Mars mission) was to use nuclear thermal as an upper stage. The reactor isn't turned on (and producing fission products, like Chernobyl and Fukishima) until everything was safely on an escape trajectory away from earth. In any kind of earthly accident scenario, the worst which could happen is to put only the initial radioactive fuel into the ecosphere. If that were Uranium-235, U235 isn't very radioactive with a half life of 70
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