Boeing's plan for Mars

kbd512 · 2015-01-27 09:56:21

Impaler wrote:

I said that solar panel technology can be developed to high power density for modest costs, not that building the whole tug is that cheap or that the cost of launch it into LEO is cheap. This means it is pointless to try to develop nuclear POWER systems for use in inner solar-system space, solar already crushes them even the proposed Sterling RTG concepts which is what I think your talking about from LANL, that kind of system is only 4x the power of RTG's and while it would be nice past Jupiter on a probe or on planetary surfaces, but it is inferior as an in-space power source.

You stated that nuclear technology requires spending inordinate amounts of time and money to produce a result. I provided a direct counter example that demonstrated that people who were more interested in producing an efficient piece of hardware that was not insanely expensive of complicated to produce could, and in point of fact, did produce a piece of hardware without requiring an inordinate amount of funding. The LANL reactor is a fission reactor, designed for spacecraft, that produces more power, weighs less than the RTG technology it replaces, and there's nothing terribly complicated about it.

Impaler wrote:

Every time I point out a flaw in a nuclear system you seem to jump to something else with out regard for it it is an engine or a power source or even the slightest concern for scaling or for the TRL. You've jumped now between no less then three different technologies that only the Nuclear word in common and are trying to treat them as one thing that somehow has all of the superlatives of each but none of the downsides, it's like some crazy tag-team wrestling match against team Nuclear.

In what way? By providing counter-examples? By stating that nuclear technology is not impossible science fiction technology? Yes, nuclear technology has downsides. Every technology does. So what?

Impaler wrote:

You know very well that our launch vehicle costs are completely separate from our TMI vehicle development and fabrication costs so don't try to bring in any hysterics about what SLS or any other launch vehicle costs (and yes SLS costs too much), all the Initial mass on the ground costs huge money to become IMLEO, we will use the best launch vehicle we can find in the end. The lower the launch vehicle cost the less we should spend on expensive TMI stages.

Launch costs always have to be factored into the cost of actually using any given piece of technology in space. Claiming that launch costs aren't a part of the implementation cost is intellectually dishonest. If the number of required launches didn't matter, then we'd just stick with using chemical propellant rockets because that technology is available today and has been available for decades.

Impaler wrote:

If you want to go by DRM 5 then you need to actually look at what kind of payload fraction the NTR stage actually gives, it's 300 mt of NTR stages (at 875–950s ISP, not one bit of downgrading from NERVA) to push 60 mt of habitat LEO->LMO->LEO. As I said earlier SEP are looking at stage masses COMPARABLE to the payload, not 5x larger, and when I say they need a bit more propellent to do a return leg that is not with refueling at Mars, that's just another ~50% more propellent at outset so you end up with a stage that is between 1.5 -2 times the size of the payload. This simply crushes NTR which required 9 SLS launches in DRM 5, the new Boeing plan is 5-6 AND brings most hardware back to LEO for reuse so each subsequent mission is even fewer SLS launches, by your own standard NTR is what is stupid if you even take a cursory glance at the numbers.

I have never advocated using solid core NTR's, but I was pointing out that the technology doesn't require kick stages to get out of LEO or back to LEO (since we're trying to get rid of that inefficient chemical propulsion technology and replace it with something better), the solid core NTR technology gives your transfer vehicle a round-trip transit time of around 12 months, and yes, I was confusing what I advocated using when I was making the comparison about mass. I made a huge mistake in the comparison. In my mind I substituted a gas core reactor's efficiency and required propellant mass for a solid core reactor's efficiency and propellant mass, because using an inefficient design is just stupid. You're right, you're right, you're right. Did I mention that you're right? Well, guess what? You're right.

If a gas core reactor is three times as efficient or better, and we know how efficient a given reactor core design will be at accelerating our propellant based on research conducted decades ago that determined how specific heat affected mass flow required to achieve a given level of thrust, then our gas core reactor will provide a specific impulse ranging from 3000s (doable) to 6000s (possible, but considerable materials development required).

If we triple our efficiency, then our propellant mass shrinks appropriately. We're still left with a heavy reactor due to shielding requirements, so what can we do about that? Well, the core cross section of a reactor fueled with Americium instead of Uranium Hexafluoride or Uranium Tetrafluoride can be reduced between 60% and 70%, depending on design, and still produce the same specific heat.

No massive radiators were or are necessary for NTR's. The heat is transferred to the propellant. Still less efficient than a Hall thruster? Obviously, but there is no spiraling out because the thrust generated is much higher, no kick stages or refueling of kick stages is required (and reverting back to chemical rocket technology to transfer orbits reduces the overall efficiency of the transfer vehicle), no massive and delicate solar arrays to fly through a shooting gallery with, and you get there as fast as a conventional rocket will reasonably take you (about six months). Since you keep talking about Zubrin, I will finally channel Side Show Bob here, "Lift and throw."

When Boeing, or anyone else for that matter, has a SEP tug that can transfer orbits without reverting back to using chemical rocket technology, capable of pushing a payload of equivalent mass as a chemical or NTR powered rocket in the same time frame, while requiring the same number or fewer heavy lift launches, then you'll have a technology that's superior to NTR technology. I don't think such a vehicle exists, but I'd love to be proven wrong.

kbd512 · 2015-01-27 10:16:19

Mark Friedenbach wrote:

Robert, the EML2 point has the significant advantage of lower delta-V requirements since it's pretty much at the edge of the Earth-Moon system, gravitationally, and also has ready 24/7 access to the Moon and/or Earth for gravitational slingshots. It does make sense to have a space station there, more sense in fact than LEO.
Of course direct to Mars or LEO rendezvous makes far more sense for early missions to Mars. In the long term an EML2 station makes sense, but right now it's just pork.

How are we going to use solar power for anything if we park a space station, orbital transfer vehicle, or any other type of spacecraft in the shade when it requires sunlight to operate?

kbd512 · 2015-01-27 10:30:52

louis wrote:

kbd - I think you misunderstood my point. What we don't have info on is how well people perform when put into mass-adjusted suits on a low G body like Mars or the Moon after prolonged exposure to zero G (we know they recover well on Earth, and we can probably hazard a guess they will perform quite will with special suits to simulate gravity on Mars or Moon). So you need the preceding phase of zero G to simulate the journey to Mars. That's why I argue for an analogue mission to the Moon - which is only 3 or 4 days away (so a rescue mission could be mounted).

I was trying to make the point that I don't want to "experiment" with whether or not humans bounce back like flubber after we've gone to the trouble and expense of transporting them to Mars. I advocated for the use of a 1G rotating habitat, better known as a wheel, that would take them to their destination in perfect operating condition. If there was any need for them to immediately leave their spacecraft to go somewhere else, as may be the case if they had a hard landing that damaged the spacecraft, then absent any other injuries they would be in good physical condition and more likely to succeed in the attempt.

It's called risk reduction. We could leave the astronauts in microgravity for six months and they would indeed survive the trip and there's no question in my mind about that. However, I want the crew to be fully functional from the moment they land and I don't want them passing out during any moderate to high G entry that may be required (hopefully high G deceleration is not required, but the Mars EDL program is not far enough along for the types of payloads we're talking about to know with any certainty) to assist with deceleration from orbit.

SpaceNut · 2015-01-27 12:38:12

From previous page the EML2 location for a new station sounds like we need a moon base to make the station from instu materials and a greater need for AG as well as radiational shielding to me to make it so that risk is mitigated for any crew that will be there. This is a mush later expansion of colonization of space and is a distraction to a first mission to mars.

The same is true of a fuel depot creation from the Mars moons unless you are sending the insitu materials to a mars orbiting space station both are a much later construction to keep exploration going with out returning all crew to earth after each Earth mars cycle.

kbd512 · 2015-01-27 13:04:07

Boeing and others want to find as many ways to not accomplish a Mars landing as possible. It keeps the millers milling and the money flowing. If you're on a cost plus contract, you have no economic incentive to deliver anything on-time and within budget.

There's landing on Mars and then there's building lunar bases (not landing on Mars), building orbital propellant depots in LEO/LLO/LMO (also not landing on Mars), and playing with space rocks (something that's completely unrelated to landing on Mars).

All of the so-called precursor missions are synonyms for "not going to Mars".

There are real problems with a Mars landing and then there are contrived problems. If we busy NASA with enough tasks that don't directly solve the problems with getting to/from and landing/living on Mars, then there won't be funding for the technology to make the landing possible.

SpaceNut · 2015-01-27 13:27:52

I agree that the contract writing is the problem unlike the one to provide a service to the ISS that Space x has these are not the same type of contracts. The contracts that Lockheed and Boeing get are developement type where as you noted it is opened ended to increased cost overrun, provide no workable item and so much more to keep the millers working....A good example was the ULA contracts to provide ET's for shuttle for a fixed dollar and a quantity that was never fully completed as Nasa only needed a minimal quantity such that each limit number was never gotten to that was in each contract for when it expired.

Impaler · 2015-01-27 14:08:20

kbd512: I'm rejecting your 'counter examples' because they are not remotely good for a basis of comparison. A Sterling RTG is the combination of two VERY old and simple technologies operating at low power density, not to mention it is a physically small device (completely incapable of doing any of the propulsion work we have been describing) which lowers development costs further. The idea that this device development cost would in ANYWAY be predictive of something like a NTR or god-forbid the GasCore NTR is appallingly dishonest. You might as well have pulled out a home smoke-detector and told me because it contains radioactive Americium that it proves Nuclear technology is cheap.

I am again going to call BS on the 3000s - 6000s ISP for your GCNTR, thouse are pie in the sky theoretical limits that assume no heat transfer to the engine itself. Our current rockets engines and nozzles are already at the very limits of material science to not melt from the heat of the exhaust, the solid core NTR has thouse same limits plus the limits of it's core material melting, all the ISP gain of the NTR is from the use of pure Hydrogen propellent, the temperatures are the same as current rockets. The Gas core would get around the core material limits but you still need a chamber to hold pressure and a nozzle to create thrust thouse things have walls and that wall is made of metal, so no higher temperature or ISP is possible.

Unless you start talking about magnetically contained Plasmas, at which point your engine is going to require huge magnets and starts to look like a Tokamak, dose this sound even remotely cheap to develop to you?

Stop throwing around these nonsense theoretical numbers off Wikipedia and telling me they are 'doable', no one has a clue how to build gas-core your describing or what kind of performance it would actually have after countless engineering compromises that would inevitably be necessary. As far as I'm concerned it's like telling me the ISP of antimatter, and for all that herculean development work your ISP is no better then SEP is getting RIGHT NOW.

And would everyone stop with the conspiratorial BS that some cabal of government/aerospace have been intentionally stopping us from going to Mars, your channeling some Zubrin really hard here. Their are absolutely VAST technological gulfs between us and Mars and limited funding to overcome these challenges, statements like 'we could have been on Mars in 1980' are pure crank nonsense on par with Moon-landing-Hoax stuff.

GW Johnson · 2015-01-27 14:24:20

We've discussed what's wrong with NASA etc elsewhere. The behavior certainly suggests there's no real intent to send men to Mars, and there's an entire spectrum of reasons as to why that would be. As for ULA (Boeing/LockMart), they make more money off gravy train technology developments than they do actually doing anything substantive. That's been the history the last 4 decades. The way we as a society do business in this arena has to change, which is rather fundamental (and unlikely), I think. I think it more likely that a visionary private entity will go first.

As for artificial gravity, two things: (1) it does not have to be a full wheel. Any long vehicle with a habitat at one end can spin end-over-end to put about 1 gee in that habitat. 4 rpm at 56 m is one gee. That's actually quite do-able, right now. (2) Until we know any better, I'd go with one full gee, both ways. We do NOT know that 0.38 gee at Mars is enough to be therapeutic. The returning crew, even from LEO, will see 4+ gees on reentry, maybe 10-15 if on a free return. They will die if unhealthy during that ride.

Radiation protection is more scare than real. Galactic cosmic radiation (GCR) is too energetic for any practical methods of shielding, you're just going to get a dose. How much you get depends upon when you go. GCR varies sinusoidally between 24 and 60 REM, in phase with the solar cycle. An active stormy sun is associated with the 24 REM, and vice versa. Current astronaut yearly limit is 50 REM, and there's a career max that varies with gender and age. A Mars crew does not need to fly outside the Van Allen Belts a second time. If they do get a bit too much in any one year (60 vs 50 REM), it's only a little bit too much. And the structures around them actually do have a tiny shielding effect.

Solar flare during active sun periods is the lethal item. This is far less energetic, and we can shield it. About 20 cm of water works fine for the worst flares, and most are nowhere that big. But some are, and you must have a way to shelter from them, or it will kill you in a matter of hours. Water, wastewater, frozen food, all qualify. You have them with you as part of your long-term life support, so use them as shielding materials, too. Not every habitable space needs shielding, just a spot where everyone can hide for a few hours. I'd make it the flight deck, so that critical maneuvers could be flown, regardless of the solar weather.

One of the remaining bugaboos is lightweight astronaut food. It only lasts 12-18 months in edible condition. Frozen and canned stuff lasts the years we need, it's just heavier. So bye-bye minimalist minimum-thrown-weight ideas!

The other bugaboo is space to stay sane, and this is usually underestimated, and it isn't arranged well, in most of the designs I have seen. People need spaces to congregate, and they need spaces to be alone (and that's not just a bunk!). They need an organized workstation, and they need something generalized and reconfigurable for recreation. The total volume per person ought to look about like the old Skylab. 3 was great in there, it'd be marginal at 6.

GW

Last edited by GW Johnson (2015-01-27 14:30:34)

kbd512 · 2015-01-27 15:43:03

Impaler wrote:

kbd512: I'm rejecting your 'counter examples' because they are not remotely good for a basis of comparison. A Sterling RTG is the combination of two VERY old and simple technologies operating at low power density, not to mention it is a physically small device (completely incapable of doing any of the propulsion work we have been describing) which lowers development costs further. The idea that this device development cost would in ANYWAY be predictive of something like a NTR or god-forbid the GasCore NTR is appallingly dishonest. You might as well have pulled out a home smoke-detector and told me because it contains radioactive Americium that it proves Nuclear technology is cheap.

I don't think any example would be satisfactory to you, short of a lightweight reactor falling from the sky and into a thrust structure of a Mars bound vessel. The premise in your argument was that any nuclear reactor requires billions to develop and decades of research. The NTR's produced in the 60's and 70's were created by men who didn't have access to a calculator, but with all our technological advantages and materials science advances, we're grossly incapable of creating a nuclear reactor for use in a spacecraft? Why? Because you say so?

Impaler wrote:

I am again going to call BS on the 3000s - 6000s ISP for your GCNTR, thouse are pie in the sky theoretical limits that assume no heat transfer to the engine itself. Our current rockets engines and nozzles are already at the very limits of material science to not melt from the heat of the exhaust, the solid core NTR has thouse same limits plus the limits of it's core material melting, all the ISP gain of the NTR is from the use of pure Hydrogen propellent, the temperatures are the same as current rockets. The Gas core would get around the core material limits but you still need a chamber to hold pressure and a nozzle to create thrust thouse things have walls and that wall is made of metal, so no higher temperature or ISP is possible.

Yes, without a magnetic nozzle a gas core reactor would slag the nozzle and slag the containment vessel. What's the exhaust temperature like for VASIMR? I've seen those things slag the instruments mounted behind them in seconds, but somehow the nozzle and device remain in one piece after literally thousands of firings.

Impaler wrote:

Unless you start talking about magnetically contained Plasmas, at which point your engine is going to require huge magnets and starts to look like a Tokamak, dose this sound even remotely cheap to develop to you?

So now you're comparing a reactor operating at tens of thousands of degrees to a fusion reactor operating at tens of millions of degrees?

Impaler wrote:

Stop throwing around these nonsense theoretical numbers off Wikipedia and telling me they are 'doable', no one has a clue how to build gas-core your describing or what kind of performance it would actually have after countless engineering compromises that would inevitably be necessary. As far as I'm concerned it's like telling me the ISP of antimatter, and for all that herculean development work your ISP is no better then SEP is getting RIGHT NOW.

The numbers come from the papers published by the group working on the reactors. Since, as you stated, we don't have any gas core reactors, what type of engineering compromises are you referring to? The herculean development effort was from a group of men far fewer in number than we have working on SLS. We're going to spend billions to develop a chemical rocket that can't put a payload into orbit that weighs as much as a Space Shuttle. Somehow that's Jim Crack dandy, but spending the money on a nuclear reactor is a waste of time and money?

Impaler wrote:

And would everyone stop with the conspiratorial BS that some cabal of government/aerospace have been intentionally stopping us from going to Mars, your channeling some Zubrin really hard here. Their are absolutely VAST technological gulfs between us and Mars and limited funding to overcome these challenges, statements like 'we could have been on Mars in 1980' are pure crank nonsense on par with Moon-landing-Hoax stuff.

What else do you attribute the complete lack of progress in space exploration for that past four decades to? You're worried about how much a gas core reactor costs or how long it takes to develop? The companies that NASA likes to do business with have literally expended tens of billions of dollars and I can't seem to find a single article of flight hardware designed for manned space exploration that's been produced in that time, unless one counts doing donuts around the Earth as manned space exploration.

Yes, if work had continued on NTR's (because the hardware was all but flight capable by the time El Presidente decided to pull the funding) and Saturn V wasn't dumped (because it was too expensive, whereas the far more costly Space Shuttle was affordable) we'd have had flight hardware capable of going to Mars. All manned space exploration stopped when the Apollo, Saturn, and NTR programs were cancelled. Everything that's followed has been about making someone a lot of money. In short, we now have a bureaucracy to doll out funding for pet projects, stroke egos, and provide the appearance of doing something while not actually accomplishing any space exploration.

RobertDyck · 2015-01-27 16:42:03

GW: I've argued that the Mars Direct habitat is a nice size. It was designed for artificial gravity during transit to Mars, and would be the surface habitat. It had the same ceiling height, and same floor area as a 60-foot class-A motorhome with slide-outs. That's the upper floor alone, not counting the lower floor. That's because the lower floor will be filled with: landing rocket engines, fuel tanks for the landing rockets, life support equipment, batteries, airlock, and a garage for the rover. It was to include a rover capable of carrying all 4 crew one-way up to 1,000km, in case the hab landed that far from the ERV. I use the word "garage" for storage space for the rover. That storage space will also have surface science equiment, and an inflatable greenhouse stored deflated/folded. So the entire lower floor will be completely unusable during transit to Mars. However, once on Mars that garage will be unpacked, that stuff won't come back in. So that will give them a single-car garage as workshop/lab. EVA prep will probably be part of that "single car garage". And once deployed, the inflatable greenhouse will be about as big as a double car garage. I think that's enough. The "Achilles' heel" of Mars Direct is the ERV. It's the size of a Dragon capsule.

I still think we need to start with this. I posted this before, it's the floor plan for the Mars Direct habitat. The original version of Mars Direct, circa (I think) 1990. The colour version published in the March 2000 issue of Scientific American.

This version has the airlock in the centre, with food storage in the walls. That makes the airlock double as radiation shelter. All updates to Mars Direct move the airlock to the ground floor. The lab is also here, but updates move the lab to the lower floor. The "garage" would serve as lab. The medical/health room doubles as exercise room; which is a good idea. This floor plan has a separate stateroom for each crewmember, with a desk. No chair, you would sit on the edge of the bed to use a desk. And the bathroom has a toilet, sink, and shower.

Care to draw an updated floor plan? Assume the outer wall will be smooth with stages of SLS, so the outer wall will be 8.4 metre diameter. How thick will the walls be? Do you want a chair for each desk? Should the bed have storage beneath (captain's bed), or fold like a Murphy bed, or fold like a railroad sleeping car? What would the radiation shelter look like?

Impaler · 2015-01-28 00:54:52

Here's some actual REAL research on what NERVA cost and how long it would have taken to complete, THIS is what you base your cost estimates on if you have a shred of honesty and it confirms everything I've been saying.

From http://history.nasa.gov/SP-4221/ch9.htm

"During FY 1970, NERVA moved into a phase of detailed design and hardware fabrication. The goal now was not further research, but rather the development of a flight-qualified engine with 75,000 pounds of thrust, at a cost of $860 million over a period of eight to nine years. The program received $88 million in FY 1970 and $85 million in FY 1971, with the funds coming jointly from NASA and the Atomic Energy Commission."

$860 million 1970's dollars is $5.25 BILLION in today's dollars. And that was just the lowest end NERVA rocket which is not even worth going back too, if you go for anything more advanced like this Gass-core nonsense it would be at least 10 times more, their is nothing but a vague notion of what this core would look like, no actual engineering AT ALL and nothing that could put any reasonable upper limit on development costs, it would be an absolutely unbounded development effort and we do not have infinite money to throw at problems.

Yes I am going to compare the Magnetic confinement needs of the GassCore NTR to a Tokamak even if they are hugely different in temperature. Because your nozzle just as slagged at 10 degrees above it's melting temperature as it is at 10 million degrees above. And your talking about an absolutely huge amount of mass and power transfer through these engines, hundreds of Megawatts possibly Gigawatts, your either going to be completely isolated from that kind of heat flux or your going to instantly melt. Any kind of low-thrust engine like a VASIMIR or a Lorentz force based thrusters is moving GRAMS of material per second and they need active cooling, they can get away with it because it's an all electric system, all heat and all plasma confinement is by microwaves and magnets respectively, hot stuff never comes into contact with cold stuff.

It should be plain enough that 'Engineering compromises' are the add-ons, losses of performance, cost over-runs that inevitably result when you move from theoretical engineering to REAL engineering and testing of a real system. No pie-in-the-sky piece of engineering survives contact with the physical world just as no battle plan survives contact with the enemy. You must be beyond naive to look at piece of theoretical potential based engineering and think that full potential is what your going to get at the end of development effort, the more speculative the concept the shorter of the goal it will fall.

kbd512 · 2015-01-28 03:43:11

Impaler wrote:

Here's some actual REAL research on what NERVA cost and how long it would have taken to complete, THIS is what you base your cost estimates on if you have a shred of honesty and it confirms everything I've been saying.
From http://history.nasa.gov/SP-4221/ch9.htm

It doesn't confirm anything other than what you want it to confirm. As I stated before, these men were designing things with slide rules and precious little knowledge of nuclear power. We had only detonated the first nuclear weapon fifteen years prior to the start of the program. This is 2015, not 1960. We have better technology at our disposal now. We're not starting from scratch.

Impaler wrote:

"During FY 1970, NERVA moved into a phase of detailed design and hardware fabrication. The goal now was not further research, but rather the development of a flight-qualified engine with 75,000 pounds of thrust, at a cost of $860 million over a period of eight to nine years. The program received $88 million in FY 1970 and $85 million in FY 1971, with the funds coming jointly from NASA and the Atomic Energy Commission."

After you falsely claimed that we were nowhere near having flight capable nuclear propulsion hardware in the early 1980's, you provide an excerpt stating that the R&D phase of the project was over and they were busy with the development of flight hardware. I'm perplexed.

Impaler wrote:

$860 million 1970's dollars is $5.25 BILLION in today's dollars. And that was just the lowest end NERVA rocket which is not even worth going back too, if you go for anything more advanced like this Gass-core nonsense it would be at least 10 times more, their is nothing but a vague notion of what this core would look like, no actual engineering AT ALL and nothing that could put any reasonable upper limit on development costs, it would be an absolutely unbounded development effort and we do not have infinite money to throw at problems.

We're going to launch SLS rockets that have already cost significantly more money to develop that use a good number of existing elements of the previous man rated launch system, but you're whining about what NERVA cost? The GCNR has had multiple studies of every aspect of the design, including CFD modeling to determine what the best shape of the core would be to reduce fuel loss, maximize the cross section of the propellant heated by core, and best use of the propellant for heat transfer.

Impaler wrote:

Yes I am going to compare the Magnetic confinement needs of the GassCore NTR to a Tokamak even if they are hugely different in temperature. Because your nozzle just as slagged at 10 degrees above it's melting temperature as it is at 10 million degrees above. And your talking about an absolutely huge amount of mass and power transfer through these engines, hundreds of Megawatts possibly Gigawatts, your either going to be completely isolated from that kind of heat flux or your going to instantly melt. Any kind of low-thrust engine like a VASIMIR or a Lorentz force based thrusters is moving GRAMS of material per second and they need active cooling, they can get away with it because it's an all electric system, all heat and all plasma confinement is by microwaves and magnets respectively, hot stuff never comes into contact with cold stuff.

Complete isolation. That's the general idea. Power level ranges between 5 and 10 GW. If a plasma that's tens of millions of degrees can be contained, is there a specific reason why a plasma that's tens of thousands of degrees can't be contained?

Impaler wrote:

It should be plain enough that 'Engineering compromises' are the add-ons, losses of performance, cost over-runs that inevitably result when you move from theoretical engineering to REAL engineering and testing of a real system. No pie-in-the-sky piece of engineering survives contact with the physical world just as no battle plan survives contact with the enemy. You must be beyond naive to look at piece of theoretical potential based engineering and think that full potential is what your going to get at the end of development effort, the more speculative the concept the shorter of the goal it will fall.

If you were to tell a Marine from 2MARDIV in August of 45, having seen three years of combat, that a single bomb smaller than a car could destroy an entire city, he'd have laughed his rear end off. Around the second week of September, he required no further convincing. Sometimes you have to suspend a little disbelief that something is possible. You make it seem as if we could spend a trillion dollars over 50 years and have nothing to show for it. You've made so many arguments that are so far out of proportion to reality that it's laughable.

Since you left out the best part of the article, I'll include it here:

This decision ended a longstanding NASA policy of developing advanced [425] engines well before there was need for them. The agency had contracted with Rocketdyne to build the F-1 as early as January 1959, over two years before Kennedy called for Apollo. Development of the J-2 dated to September 1960. The demise of NERVA meant that nobody would be flying to Mars, perhaps not even within our lifetimes. <- [Edited] This is what the loss of the Saturn and space nuclear propulsion program means in a context that everyone here should be able to understand.

Last edited by kbd512 (2015-01-28 04:14:39)

Impaler · 2015-01-30 02:21:16

kbd512 wrote:

It doesn't confirm anything other than what you want it to confirm. As I stated before, these men were designing things with slide rules and precious little knowledge of nuclear power. We had only detonated the first nuclear weapon fifteen years prior to the start of the program. This is 2015, not 1960. We have better technology at our disposal now. We're not starting from scratch.

Just a second ago you were praising the slide-rules, now they seem to be stone knives and bear skins. Our tools are better now yes, but development costs in Aerospace and Nuclear science are still astronomical and a lot of degeneration has occurred much of what they would have accomplished back then would need to be redone.

kbd512 wrote:

After you falsely claimed that we were nowhere near having flight capable nuclear propulsion hardware in the early 1980's, you provide an excerpt stating that the R&D phase of the project was over and they were busy with the development of flight hardware. I'm perplexed.

They did not have a flight capable system, subsystems were being built and tested but had never been assembled into a finished engine, they were hoping to have a finished engine after several more years of development. I don't see any reason to believe they would not have gotten their with the time and money originally budgeted, but the program was halted many years short of that goal. You seem to be under the false impression that they were one screw turn away from completion.

kbd512 wrote:

We're going to launch SLS rockets that have already cost significantly more money to develop that use a good number of existing elements of the previous man rated launch system, but you're whining about what NERVA cost? The GCNR has had multiple studies of every aspect of the design, including CFD modeling to determine what the best shape of the core would be to reduce fuel loss, maximize the cross section of the propellant heated by core, and best use of the propellant for heat transfer.

Why must you keep throwing SLS at me as if I am an advocate for it or it is somehow in competition with NTR technology? Dose that fact that just assembling this SLS rocket out of 'off the shelf' shuttle leftovers is in fact costing ungodly amounts of money give you no pause for how expensive right rocket development is? And yet your completely sure that development of Nuclear propulsion with be chump change, and not just solid core but some crazy gass core idea that your convinced is worth it because of some numbers you read off Wikipedia.

kbd512 wrote:

Complete isolation. That's the general idea. Power level ranges between 5 and 10 GW. If a plasma that's tens of millions of degrees can be contained, is there a specific reason why a plasma that's tens of thousands of degrees can't be contained?

Of course it can be contained WITH A HUGE ENOUGH MAGNET, that is the problem! Your not going to control a Gigawatt of plasma with a something that has the kind of mass ratios that we have in the combustion-chamber/nozzle of a chemical engine, a magnetic equivalent is going to be massive and the thrust:weight of the engine is going to tank.

kbd512 wrote:

If you were to tell a Marine from 2MARDIV in August of 45, having seen three years of combat, that a single bomb smaller than a car could destroy an entire city, he'd have laughed his rear end off. Around the second week of September, he required no further convincing. Sometimes you have to suspend a little disbelief that something is possible. You make it seem as if we could spend a trillion dollars over 50 years and have nothing to show for it. You've made so many arguments that are so far out of proportion to reality that it's laughable.

Now your siting the Manhattan project to me as proof of affordability, have you lost your mind? This is typical space cadet thinking, damn the costs we can do ANYTHING!!!! This is the kind of thinking that has lead to our unending series of space boondoggle, and while you seem to be able to recognize all the other boondoggles like SLS but you have a giant blind-spot for your own boondoggle. I've told you repeatedly that Nuclear rockets are 1) Expensive to develop and 2) don't have the performance to be attractive compared to Electric alternatives. And your response is basically to insist against all evidence that Nuclear rockets will be cheap to develop if we just 'hope' and 'try harder'.

I think your problem is that you think COST during development is just another metric of performance that can be beaten into submission by engineering, like needing more speed, more thrust, more what ever. When we hit a snag in the development we will just apply more engineering to 'fix' the cost thing like we would fix any other performance issue. That is not how it works, cost is not something that goes down as you engineer something more, it only goes UP because cost is incurred by engineering. No act of brilliant engineering can un-spend a depleted budget and when your doing cutting edge engineering your going to frequently hit snags that force costs upwards above the original estimate. Costs are more of a floor with the general technology or system architecture setting your best case with reality being considerably above that and a worst case scenario vastly higher. Only after something is DONE being developed can you even hope to start reducing costs, and that is a slow iterative process that's only justified by a high volume of usage to amortize the improvement over.

kbd512 · 2015-01-30 05:05:06

Impaler wrote:

Just a second ago you were praising the slide-rules, now they seem to be stone knives and bear skins. Our tools are better now yes, but development costs in Aerospace and Nuclear science are still astronomical and a lot of degeneration has occurred much of what they would have accomplished back then would need to be redone.

Did everyone at LANL have their brain fall out of their head recently? I stated that men with far less than what we have to work with today developed nuclear rocket propulsion from scratch. With all of our advanced technology and computational capabilities, are we somehow utterly incapable of creating a fission reactor and flowing hydrogen through it?

Impaler wrote:

They did not have a flight capable system, subsystems were being built and tested but had never been assembled into a finished engine, they were hoping to have a finished engine after several more years of development. I don't see any reason to believe they would not have gotten their with the time and money originally budgeted, but the program was halted many years short of that goal. You seem to be under the false impression that they were one screw turn away from completion.

No, they didn't just have to fuel a rocket and launch it, but to pretend that there was or is some sort of absolute impossibility to picking up where we left off is just silly.

Impaler wrote:

Why must you keep throwing SLS at me as if I am an advocate for it or it is somehow in competition with NTR technology? Dose that fact that just assembling this SLS rocket out of 'off the shelf' shuttle leftovers is in fact costing ungodly amounts of money give you no pause for how expensive right rocket development is? And yet your completely sure that development of Nuclear propulsion with be chump change, and not just solid core but some crazy gass core idea that your convinced is worth it because of some numbers you read off Wikipedia.

Yes, we're spending billions to re-invent Saturn V using inappropriate hardware and the result is a rocket that can't even throw an orbiter into LEO. If we think nothing of spending billions to re-invent what we had four decades ago, in terms of chemical rocket throw capability, then we can damn well spend some money on something that has long term payoff and permits us to explore virtually all of the solar system. Stop with the Wikipedia nonsense. The information I have comes from the papers published by the people who worked on the technology.

Impaler wrote:

Of course it can be contained WITH A HUGE ENOUGH MAGNET, that is the problem! Your not going to control a Gigawatt of plasma with a something that has the kind of mass ratios that we have in the combustion-chamber/nozzle of a chemical engine, a magnetic equivalent is going to be massive and the thrust:weight of the engine is going to tank.

We could use a huge magnet. Or we could use technology that permits us to direct a magnetic field… Muchas gracias, Alvaro.

Impaler wrote:

Now your siting the Manhattan project to me as proof of affordability, have you lost your mind? This is typical space cadet thinking, damn the costs we can do ANYTHING!!!! This is the kind of thinking that has lead to our unending series of space boondoggle, and while you seem to be able to recognize all the other boondoggles like SLS but you have a giant blind-spot for your own boondoggle. I've told you repeatedly that Nuclear rockets are 1) Expensive to develop and 2) don't have the performance to be attractive compared to Electric alternatives. And your response is basically to insist against all evidence that Nuclear rockets will be cheap to develop if we just 'hope' and 'try harder'.

No advanced propulsion technology has ever been "cheap" to develop and this solar electric propulsion that you so love is not an exception to that rule. Many billions of dollars have been invested in the technology and that is the only reason it works as well as it does today. Rather than blowing money on unnecessary make-work projects, like Orion/SLS, I'd rather see NASA actually develop a technology that permits us to explore all of our own solar system, instead of just the parts that are close to the Sun. In finance, it's what you'd call a long term investment. It requires enough wisdom to accept that there will be a tomorrow. Apparently you think it's too difficult or maybe you can only focus on what's right in front of you. I, for one, am quite thankful that those who came before us did not give up simply because a particular problem was difficult or expensive to solve. Few things worthwhile are simple, cheap, or easy. There is such a thing as squandering money and opportunity, though. That is what I believe Orion/SLS are. I have nothing against your precious solar electric technology, but the technology does have limitations and I would like to see development of a complementary technology that does not have those limitations.

Impaler wrote:

I think your problem is that you think COST during development is just another metric of performance that can be beaten into submission by engineering, like needing more speed, more thrust, more what ever. When we hit a snag in the development we will just apply more engineering to 'fix' the cost thing like we would fix any other performance issue. That is not how it works, cost is not something that goes down as you engineer something more, it only goes UP because cost is incurred by engineering. No act of brilliant engineering can un-spend a depleted budget and when your doing cutting edge engineering your going to frequently hit snags that force costs upwards above the original estimate. Costs are more of a floor with the general technology or system architecture setting your best case with reality being considerably above that and a worst case scenario vastly higher. Only after something is DONE being developed can you even hope to start reducing costs, and that is a slow iterative process that's only justified by a high volume of usage to amortize the improvement over.

I believe that you actually have to try to do something before you know how much it's going to cost. Since we're doing nothing of the sort, your guesses about how much development would cost and how long it would take are every bit as imaginary as mine are. I believe that the cost of development would not be outrageous or impossible for NASA to bear, but it would mean that some money squandering programs would have to go.

Impaler · 2015-01-30 14:13:44

kbd512 wrote:

Did everyone at LANL have their brain fall out of their head recently? I stated that men with far less than what we have to work with today developed nuclear rocket propulsion from scratch. With all of our advanced technology and computational capabilities, are we somehow utterly incapable of creating a fission reactor and flowing hydrogen through it?

Typical space cadet straw-man, I've said it can't be done cheaply and your exaggerating that to 'impossible to achieve at all'. I have said repeatedly that it COULD be done just that it will be gawd awful expensive. Stop trying to put words in my mouth.

kbd512 wrote:

No, they didn't just have to fuel a rocket and launch it, but to pretend that there was or is some sort of absolute impossibility to picking up where we left off is just silly.

Again your trying to turn my critique of cost in to a proclamation that the technology cant be developed at all. How can a person be this dishonest?

kbd512 wrote:

Yes, we're spending billions to re-invent Saturn V using inappropriate hardware and the result is a rocket that can't even throw an orbiter into LEO. If we think nothing of spending billions to re-invent what we had four decades ago, in terms of chemical rocket throw capability, then we can damn well spend some money on something that has long term payoff and permits us to explore virtually all of the solar system. Stop with the Wikipedia nonsense. The information I have comes from the papers published by the people who worked on the technology.

Then site your sources, give me some links to real technical papers.

kbd512 wrote:

We could use a huge magnet. Or we could use technology that permits us to direct a magnetic field… Muchas gracias, Alvaro.

What part of huge mass killing thrust:weight ratio did you not understand? How dose 'directing' a magnetic field reduce the mass? Are you simply grasping at random words to avoid acknowledging this problem? Do you have even the slightest idea what your talking about?

kbd512 wrote:

No advanced propulsion technology has ever been "cheap" to develop and this solar electric propulsion that you so love is not an exception to that rule. Many billions of dollars have been invested in the technology and that is the only reason it works as well as it does today. Rather than blowing money on unnecessary make-work projects, like Orion/SLS, I'd rather see NASA actually develop a technology that permits us to explore all of our own solar system, instead of just the parts that are close to the Sun. In finance, it's what you'd call a long term investment. It requires enough wisdom to accept that there will be a tomorrow. Apparently you think it's too difficult or maybe you can only focus on what's right in front of you. I, for one, am quite thankful that those who came before us did not give up simply because a particular problem was difficult or expensive to solve. Few things worthwhile are simple, cheap, or easy. There is such a thing as squandering money and opportunity, though. That is what I believe Orion/SLS are. I have nothing against your precious solar electric technology, but the technology does have limitations and I would like to see development of a complementary technology that does not have those limitations.

As usual you couldn't be more wrong, SEP technology has been ongoing for a decade already as part of NASA's Exploration Technology development program, that whole program has a budget of only ~200 million a year and is developing a dozen different things at any one time such as hypersonic decelerators and thouse Sterling RTG you mentioned earlier. Because this is already a know technology that is actively being used by commercial satellites every day the risks for incremental refinement are very low. The Asteroid Redirect vehicle has been budgeted 133 million per year http://optics.org/news/5/3/3 and that is for both the technology and to actually make for the WHOLE vehicle.

As for limitations, please elaborate, you seem to have no problem assuming the highest theoretical possibilities of Nuclear propulsion as givens so why don't you apply the same standard to Electric propulsion? You can not seriously be worried about transit times, it has been shown conclusively that SEP can perform a transit to Mars that is comparable to a high thrust system when provided with adequate power.

kbd512 wrote:

I believe that you actually have to try to do something before you know how much it's going to cost. Since we're doing nothing of the sort, your guesses about how much development would cost and how long it would take are every bit as imaginary as mine are. I believe that the cost of development would not be outrageous or impossible for NASA to bear, but it would mean that some money squandering programs would have to go.

Again wrong, no less then wrong your expressing nothing but a blind wish and an appeal to ignorance. We can make very reasonable minimum estimates of cost based on the TRL, the size/energy/mass of the thing we want to develop and basic nature of the technology in question. Nuclear Thermal Rockets as a technology BIG, HIGH ENERGY, HIGH DIFFICULTY. The NERVA has a reasonable TRL 5-6 which is the only factor that isn't bad for it, but even here it is inferior to SEP which is TRL 9. The size, mass and energy density of SEP are all lower then Nuclear propulsion systems, Electric propulsion systems can be tested in vacuum chambers, nuclear rockets aren't going to be tested in the earths atmosphere ever again and would require extensive in-space testing. No honest estimate would put SEP and NTR even remotely in the same ballpark for development costs.

Should we cancel SLS and spend all that money on technology, YES, but not one dime of it on Nuclear propulsion.

kbd512 · 2015-01-31 00:57:36

Impaler wrote:

Typical space cadet straw-man, I've said it can't be done cheaply and your exaggerating that to 'impossible to achieve at all'. I have said repeatedly that it COULD be done just that it will be gawd awful expensive. Stop trying to put words in my mouth.

Calling people names isn't a form of argument, it's just a personal attack. Could development of a GCNR be expensive? Yes. Will it be dramatically more expensive than any other advanced technology that mankind has developed? If history is any indicator, probably not. It won't be done on feel good funding, though. Let's put it that way.

Impaler wrote:

Again your trying to turn my critique of cost in to a proclamation that the technology cant be developed at all. How can a person be this dishonest?

Your argument is that development of GCNR will be extremely expensive and, as you continue to note, it isn't available right now. The reason it isn't available right now should be fairly obvious. Nobody is working on the technology.

Impaler wrote:

Then site your sources, give me some links to real technical papers.

http://www.osti.gov/scitech/servlets/purl/4017976 <- It can be done

https://archive.org/details/nasa_techdoc_19720013996

http://www.osti.gov/scitech/servlets/purl/5175780

http://deepblue.lib.umich.edu/bitstream … /585_1.pdf <- Don't know if you consider studies to be technical papers or not, but the information in the study was based on actual experimentation with Americium

http://www.researchgate.net/publication … st_reactor

http://books.google.com/books/about/A_F … IDAAAAIAAJ

http://books.google.com/books/about/Sim … vsvLqoOf0C

http://www.researchgate.net/publication … ear_rocket

http://www.researchgate.net/publication … et_concept

http://www.researchgate.net/publication … ded_Risers

http://www.tnw.tudelft.nl/fileadmin/Fac … uwerda.pdf

https://smartech.gatech.edu/bitstream/h … 313_v2.pdf

http://arc.aiaa.org/doi/abs/10.2514/3.2 … alCode=jsr

http://papers.sae.org/929347/ <- Power, not propulsion

http://adsabs.harvard.edu//abs/1988snps.symp..473D <- Mo Powa!

http://alexandria.tue.nl/repository/fre … 620304.pdf

http://www.ans.org/pubs/journals/nt/a_3480

http://www.academia.edu/1705961/Nuclear … Technology

http://www.freepatentsonline.com/3399534.pdf <- Not a technical paper, but a patent for a GCNR from TRW

http://www.inl.gov/technicalpublication … 517271.pdf <- NASA blew some cash on studies of potential fuel candidates for solid core NTR's for Mars DRM 5.0

http://www.inl.gov/technicalpublication … 394162.pdf <- Same as above

https://books.google.com/books?id=Foo-y … or&f=false <- Not a technical paper, but more of a "this is how it could work" paper

https://books.google.com/books?id=aI9Qh … or&f=false <- More of the same

http://www.ebay.com/itm/Gas-Core-Nuclea … 1451583969 <- GCNR Info on eBay!

Impaler wrote:

What part of huge mass killing thrust:weight ratio did you not understand? How dose 'directing' a magnetic field reduce the mass? Are you simply grasping at random words to avoid acknowledging this problem? Do you have even the slightest idea what your talking about?

An enormous magnet is not necessary if you can direct and intensify the magnetic pressure generated. Alvaro Sanchez, from the Autonomous University of Barcelona in Spain has done some ground breaking work in development of this technology.

Impaler wrote:

As usual you couldn't be more wrong, SEP technology has been ongoing for a decade already as part of NASA's Exploration Technology development program, that whole program has a budget of only ~200 million a year and is developing a dozen different things at any one time such as hypersonic decelerators and thouse Sterling RTG you mentioned earlier. Because this is already a know technology that is actively being used by commercial satellites every day the risks for incremental refinement are very low. The Asteroid Redirect vehicle has been budgeted 133 million per year http://optics.org/news/5/3/3 and that is for both the technology and to actually make for the WHOLE vehicle.

Solar panels and SEP technology didn't leap into existence with NASA funding ten years ago. Aerojet-Rocketdyne put the first electric thruster on a spacecraft more than thirty years ago. Many billions of dollars have been invested in solar technology and electric propulsion for spacecraft and rightly so. I see no reason whatsoever to discontinue funding. SEP technology is quite useful if the period of time in space is measured in years and maximum efficiency is more important than how fast you get there. The highest efficiency electric thruster flown to date was, I think, on JPL/NASA's Dawn mission. IIRC, the thruster's efficiency was quoted as being around 3100s.

Impaler wrote:

As for limitations, please elaborate, you seem to have no problem assuming the highest theoretical possibilities of Nuclear propulsion as givens so why don't you apply the same standard to Electric propulsion? You can not seriously be worried about transit times, it has been shown conclusively that SEP can perform a transit to Mars that is comparable to a high thrust system when provided with adequate power.

The highest theoretical limit of efficiency for a gas core NTR was calculated to be around 6000s with a core temperature around 100,000K. I think 3000s is achievable. NTR efficiency centers around how fast you can accelerate the propellant through the core with the thermal flux provided by the fissioning core material. NTR efficiency is not a SWAG on the part of the engineers who were involved with Rover and NERVA, it was determined through actual testing. Whether it is practical to approach the limits of the technology has a lot to do with materials development and the size of the reactor. A reactor the size of a house is obviously a non-starter for space propulsion applications.

Impaler wrote:

Again wrong, no less then wrong your expressing nothing but a blind wish and an appeal to ignorance. We can make very reasonable minimum estimates of cost based on the TRL, the size/energy/mass of the thing we want to develop and basic nature of the technology in question. Nuclear Thermal Rockets as a technology BIG, HIGH ENERGY, HIGH DIFFICULTY. The NERVA has a reasonable TRL 5-6 which is the only factor that isn't bad for it, but even here it is inferior to SEP which is TRL 9. The size, mass and energy density of SEP are all lower then Nuclear propulsion systems, Electric propulsion systems can be tested in vacuum chambers, nuclear rockets aren't going to be tested in the earths atmosphere ever again and would require extensive in-space testing. No honest estimate would put SEP and NTR even remotely in the same ballpark for development costs.

I think a lot of the work performed in NERVA is relevant and applicable to GCNR design and there's no need to reinvent the wheel to prove that we know what we know. NASA is spending what precious little money it does have to try to recreate the fuel elements used in the NERVA engines.

As far as testing is concerned, it can be done underground. The US already stores nuclear waste underground in rather expansive facilities. So long as we're not overly concerned with nuclear waste becoming contaminated with radiation if there's a containment breach, I would perform testing there.

An honest estimate of what a transition from gas powered motor vehicles to electric powered motor vehicles would cost should not ignore the many billions expended to develop internal combustion engines, the billions spent maintaining them, and the billions spent making them more efficient so we're not all choking down the exhaust fumes. Every new technology has up-front costs. Many billions of dollars have already been poured into research for the technologies required to make SEP a reality and it didn't happen in five, ten, or even twenty-five years. The SEP tech doesn't exist in a neat vacuum where only the cost of some small portion of the overall development effort should be considered.

Impaler wrote:

Should we cancel SLS and spend all that money on technology, YES, but not one dime of it on Nuclear propulsion.

Do you work for a company that sells solar panels or electric thrusters?

RobertDyck · 2015-01-31 03:11:14

You guys are having a nice argument. But I would like to point out development of NERVA was completed so far in 1974 that the next step was to test it in Earth orbit. There was nothing left to do before that. All testing before testing in space was finished.

Quaoar · 2015-01-31 04:51:08

RobertDyck wrote:

You guys are having a nice argument. But I would like to point out development of NERVA was completed so far in 1974 that the next step was to test it in Earth orbit. There was nothing left to do before that. All testing before testing in space was finished.

And now we have even better materials like carbon-carbon composite and uranium tricarbide fuel wafers that can be arranged in honeycomb square lattice able to work up to 3300 K, or assembled in stacks of grooved fuel rings.

http://ufdcimages.uflib.ufl.edu/UF/E0/0 … gouw_r.pdf

http://ntrs.nasa.gov/archive/nasa/casi. … 008640.pdf

If we want we are able to develop in 10-15 years a Copernicus like spaceship, with artificial gravity and high performance rockets with more than 1000s of Isp.

http://ntrs.nasa.gov/archive/nasa/casi. … 003776.pdf

SEP is good for unmanned space tugs in the inner solar system, but if we want to go to Jupiter and Saturn, nuclear rockets are a must.

Last edited by Quaoar (2015-01-31 04:53:59)

kbd512 · 2015-01-31 13:02:03

A solid core NTR could certainly be developed and flight tested sooner than a gas core NTR, but as Impaler pointed out, the payload mass fraction doesn't compare favorably to SEP solutions.

The problems I have with the SEP solutions are as follows:

- Greater number of assembly/deployment and orbital transfer operations

- Orbital transfers take months to accomplish without chemical propellant kick stages (if active radiation shielding can be made sufficiently lightweight, this is less of a problem for a manned vehicle or a solution where the crew is ferried to the transfer vehicle after it's at a Lagrange point, but TRL for active shielding is even lower than it is for gas core reactors; I'm still confident active shielding can be accomplished in another ten years or so)

- Chemical propellant kick stages are required to shorten orbital transfer times (well within our technological capability, but it adds mass to a SEP tug that already requires a SLS launch of its own and reduces overall efficiency)

- Solar panels the size of something a SEP tug would use would undoubtedly increase the chance of collision with space debris (I'd say deployment of the panels prior to reaching a Lagrange point is a mission risk; If a significant portion of an array is damaged or rendered inoperable, there may not be sufficient power to complete an orbital transfer in a timely manner)

- Even if active radiation shielding is available and some measure of artificial gravity can be provided, you're adding months of time in space to the mission without the kick stages

All manned space exploration missions up to now have started in LEO, involved a burn for orbital transfer, and a burn for orbital insertion. Spiraling in/out is a new way of accomplishing orbital transfers, but it obviously works.

How much would a SEP tug that can transfer from LEO to LMO or LLO (even if we have to add kick stages to break orbits), and make the transfer in six months or less weigh?

Is it possible to provide artificial gravity for the crew or would that adversely affect operation of the tug?

Impaler · 2015-01-31 19:25:19

kbd512 wrote:

Calling people names isn't a form of argument, it's just a personal attack. Could development of a GCNR be expensive? Yes. Will it be dramatically more expensive than any other advanced technology that mankind has developed? If history is any indicator, probably not. It won't be done on feel good funding, though. Let's put it that way.

All historical evidence says just the opposite, you are clearly basing your opinion on personal wishes and desires and not actual evidence.

kbd512 wrote:

Your argument is that development of GCNR will be extremely expensive and, as you continue to note, it isn't available right now. The reason it isn't available right now should be fairly obvious. Nobody is working on the technology.

NOBODY is working on it BECAUSE it is expensive (AND pointless) not the other way around, think about that for one second, Russia has absolutely no qualms with nuclear technology but they aren't doing it. Instead EVERY MAJOR SPACE AGENCY is putting money into SEP. Do you really think that NASA, ESA, JAXA, Roscosmos are ALL stupider then you?

kbd512 wrote:

An enormous magnet is not necessary if you can direct and intensify the magnetic pressure generated. Alvaro Sanchez, from the Autonomous University of Barcelona in Spain has done some ground breaking work in development of this technology.

Site it and give me some kind of estimate.

kbd512 wrote:

Solar panels and SEP technology didn't leap into existence with NASA funding ten years ago. Aerojet-Rocketdyne put the first electric thruster on a spacecraft more than thirty years ago. Many billions of dollars have been invested in solar technology and electric propulsion for spacecraft and rightly so. I see no reason whatsoever to discontinue funding. SEP technology is quite useful if the period of time in space is measured in years and maximum efficiency is more important than how fast you get there. The highest efficiency electric thruster flown to date was, I think, on JPL/NASA's Dawn mission. IIRC, the thruster's efficiency was quoted as being around 3100s.

As usually you are utterly ignorant of the technology your criticizing. Dawn was launched more then 10 years ago and we have had whole generations of thruster tech between then and now. The NEXT ion thrusters which completed 5 years of endurance testing in 2010 gets 4200s while being having higher thrust:weight. Hall thrusters running on Krypton are hitting ~3000s ranges and will likely start to take over from gridded ion thrusters going forward because their better thrust density and ability to throttle across a wider range of ISP, the ARM mission would likely use them. Also efficiency in a Electric thruster has a meaning different from ISP (in fact it is sloppy to ever use efficiency as a synonym for ISP in regular rockets), it means the percentage of electrical energy converted to kinetic energy and it is around 50-70% for most thrusters and rising as technology improves.

kbd512 wrote:

The highest theoretical limit of efficiency for a gas core NTR was calculated to be around 6000s with a core temperature around 100,000K. I think 3000s is achievable. NTR efficiency centers around how fast you can accelerate the propellant through the core with the thermal flux provided by the fissioning core material. NTR efficiency is not a SWAG on the part of the engineers who were involved with Rover and NERVA, it was determined through actual testing. Whether it is practical to approach the limits of the technology has a lot to do with materials development and the size of the reactor. A reactor the size of a house is obviously a non-starter for space propulsion applications.

Your 'think is achievable' seems to be nothing more then chopping the first number in half, it's baseless speculation on your part. Your continuing to pretend that NERVA somehow validates Gas-Core, they are RADICALLY different and the Gas Core is orders of magnitude harder. NERVA operates at ~850s ISP and completely in the range of NORMAL ROCKET TEMPERATURES. Gas Core would push material science into unknown territory to contain the temperatures AND pressures to achieve these theoretical numbers, because these numbers assume no barriers imposed by materials being slagged.

kbd512 wrote:

I think a lot of the work performed in NERVA is relevant and applicable to GCNR design and there's no need to reinvent the wheel to prove that we know what we know. NASA is spending what precious little money it does have to try to recreate the fuel elements used in the NERVA engines.

Again your so called thinking here is dead wrong. And as for making fuel it's actually the DOE that's doing that, but it is fuel for RTG, not the stuff that would go into NERVA, these RTG fuels don't get anywhere near that hot.

kbd512 wrote:

As far as testing is concerned, it can be done underground. The US already stores nuclear waste underground in rather expansive facilities. So long as we're not overly concerned with nuclear waste becoming contaminated with radiation if there's a containment breach, I would perform testing there.

Underground might be cheaper then launching, but it won't be CHEAP. You need to have a cavity capable of holding all that exhausted gas which is absolutely huge.

kbd512 wrote:

An honest estimate of what a transition from gas powered motor vehicles to electric powered motor vehicles would cost should not ignore the many billions expended to develop internal combustion engines, the billions spent maintaining them, and the billions spent making them more efficient so we're not all choking down the exhaust fumes. Every new technology has up-front costs. Many billions of dollars have already been poured into research for the technologies required to make SEP a reality and it didn't happen in five, ten, or even twenty-five years. The SEP tech doesn't exist in a neat vacuum where only the cost of some small portion of the overall development effort should be considered.

Oh brother a sunk-cost fallacy, your really embarrassing yourself now. All costs in the past are GONE, UNRECOVERABLE, IRRELEVANT. We make all decisions on future actions with the world as it currently is as a given, if a million dollar project $2 from completion and and a $1 alternative appears you cancel the incomplete project and save $1. Yes billions have been spent on Solar technology, and millions on electric propulsion, but ALL of thouse costs are both irrelevant now AND in fact thouse costs already payed for themselves a hundred times over in making ALL OUR CURRENT SATELLITES possible which provide services every year valued at over $100 BILLION. All that matters is the MARGINAL costs to get the next generation improvement and the benefits of that next generation vs the marginal costs. This is why these technologies are still being developed, their benefits are huge and the costs are less then the near term benefits. Any alternative propulsion technology is going to need to compare it's full costs vs the marginal costs of improved SEP, this is why Nuclear is never going to happen, it's decades behind and falling further behind every day.

kbd512 wrote:

Do you work for a company that sells solar panels or electric thrusters?

No, I just know how to judge technologies rationally.

Last edited by Impaler (2015-01-31 21:19:31)

kbd512 · 2015-01-31 22:03:59

Impaler wrote:

All historical evidence says just the opposite, you are clearly basing your opinion on personal wishes and desires and not actual evidence.

All historical evidence says that technology development costs billions.

If those billions spent lead to a technology that permits us to explore virtually all of our solar system, I consider that a bargain.

Impaler wrote:

NOBODY is working on it BECAUSE it is expensive (AND pointless) not the other way around, think about that for one second, Russia has absolutely no qualms with nuclear technology but they aren't doing it. Instead EVERY MAJOR SPACE AGENCY is putting money into SEP. Do you really think that NASA, ESA, JAXA, Roscosmos are ALL stupider then you?

Then why does NASA have nuclear engineers trying to re-create a nuclear rocket engine? Are they stupider than you?

Impaler wrote:

Site it and give me some kind of estimate.

Do your own searching and your own estimating. I already provided plenty of technical papers that detail how a GCNR would work, experimentation conducted for GCNR research and development, and results. Give your own estimate so I can then attack it and say that it's unrealistic without providing any evidence, which is the only thing you've done up to this point.

Impaler wrote:

As usually you are utterly ignorant of the technology your criticizing. Dawn was launched more then 10 years ago and we have had whole generations of thruster tech between then and now. The NEXT ion thrusters which completed 5 years of endurance testing in 2010 gets 4200s while being having higher thrust:weight. Hall thrusters running on Krypton are hitting ~3000s ranges and will likely start to take over from gridded ion thrusters going forward because their better thrust density and ability to throttle across a wider range of ISP, the ARM mission would likely use them. Also efficiency in a Electric thruster has a meaning different from ISP (in fact it is sloppy to ever use efficiency as a synonym for ISP in regular rockets), it means the percentage of electrical energy converted to kinetic energy and it is around 50-70% for most thrusters and rising as technology improves.

By your own logic a, nuclear rocket engine in a lab is years away from flight testing and may as well be science fiction. So, I'm applying the same logic to your own flawed precepts. Whereupon an engine has flown in space or NASA decides to fund something, the technology leaps into existence and we start counting development dollars. Go fish.

Impaler wrote:

Your 'think is achievable' seems to be nothing more then chopping the first number in half, it's baseless speculation on your part. Your continuing to pretend that NERVA somehow validates Gas-Core, they are RADICALLY different and the Gas Core is orders of magnitude harder. NERVA operates at ~850s ISP and completely in the range of NORMAL ROCKET TEMPERATURES. Gas Core would push material science into unknown territory to contain the temperatures AND pressures to achieve these theoretical numbers, because these numbers assume no barriers imposed by materials being slagged.

What I "think is achievable" is based off of flow experiments, the demonstrated ability of a seeded hydrogen propellant to absorb the thermal flux from the reactor core, and LANL modeling of a reactor core designed to minimize fuel loss while maximizing propellant flow for cooling and propulsive force.

Impaler wrote:

Again your so called thinking here is dead wrong. And as for making fuel it's actually the DOE that's doing that, but it is fuel for RTG, not the stuff that would go into NERVA, these RTG fuels don't get anywhere near that hot.

Have you actually read anything about nuclear rocket engine technology? RTG fuel? What in the world does this have to do with using UF4, UF6, or Am in a GCNR?

The parts of NERVA that are applicable to design of a GCNR are determination of Isp from actual experimentation, the cold flow experiments, the one hot flow experiment, and use of seeded propellants.

Impaler wrote:

Underground might be cheaper then launching, but it won't be CHEAP. You need to have a cavity capable of holding all that exhausted gas which is absolutely huge.

No, it will not be "CHEAP" with capital lettering that you so love. The engines I want to see developed have thrust levels comparable to a RL-10. Go look at some pictures of the salt mines where we store radioactive waste.

Impaler wrote:

Oh brother a sunk-cost fallacy, your really embarrassing yourself now. All costs in the past are GONE, UNRECOVERABLE, IRRELEVANT. We make all decisions on future actions with the world as it currently is as a given, if a million dollar project $2 from completion and and a $1 alternative appears you cancel the incomplete project and save $1. Yes billions have been spent on Solar technology, and millions on electric propulsion, but ALL of thouse costs are both irrelevant now AND in fact thouse costs already payed for themselves a hundred times over in making ALL OUR CURRENT SATELLITES possible which provide services every year valued at over $100 BILLION. All that matters is the MARGINAL costs to get the next generation improvement and the benefits of that next generation vs the marginal costs. This is why these technologies are still being developed, their benefits are huge and the costs are less then the near term benefits. Any alternative propulsion technology is going to need to compare it's full costs vs the marginal costs of improved SEP, this is why Nuclear is never going to happen, it's decades behind and falling further behind every day.

Oh brother, the only money that matters is future money fallacy. Yes, you are embarrassing yourself. Money spent to achieve a capability is not irrelevant. Far better economists than you universally agree on this point. The only logically valid argument you've presented was that our development of nuclear propulsion technology lags behind because we're not putting much funding into it.

Impaler wrote:

No, I just know how to judge technologies rationally.

If we used your rationality for technology development, we'd still be riding around on horses. After all, that new gasoline engine will cost billions to develop and that horse gets you from point A to point B, just like the cars of the early 1900's. You'd fit right in with the current crop of Boeing execs, though.

Impaler · 2015-02-01 00:38:45

Are you truly going to stand on this ridiculous sunk-cost fallacy? That all the money spent in the past to develop solar should be added up and used decide if future investment is justified? Will we add up all the money ever spend on Nuclear technology as well? Past costs for every technology are irrelevant, we should only ever look at the future costs and the future additional benefits thouse investments will bring. This is a WELL established principle which better economists they both of us came up with, if you are not capable of understanding it then you have no business making ANY kind of decision involving money PERIOD.

Frankly your arguments have been one of poorer defenses of NTR that I have seen on this forum. Other NTR proponents at least know something about SEP, and stick to basic NERVA types systems without going into fantasy land Gass-Core stuff. This entire thread has been pearls-before-swine waste of my time as it seems every NTR advocate has a cranium capable of shielding them from not only from deadly neutron radiation but facts and reason as well.

Fortunately NASA make the right choice in the 1990's to commit to SEP and to drop Nuclear like bag of kittens into a river, we have been on that development track now for 20 years and it's an unstoppable freight train of fruitful development that is not going to stop. Instead it is going to open the solar-system to larger and larger probes and eventually manned missions BLEO. But I expect even THEN dolts on this forum will still be pining their hearts away on Nuclear fantasies.

Last edited by Impaler (2015-02-01 00:40:16)

kbd512 · 2015-02-01 02:38:55

Impaler wrote:

Are you truly going to stand on this ridiculous sunk-cost fallacy? That all the money spent in the past to develop solar should be added up and used decide if future investment is justified? Will we add up all the money ever spend on Nuclear technology as well? Past costs for every technology are irrelevant, we should only ever look at the future costs and the future additional benefits thouse investments will bring. This is a WELL established principle which better economists they both of us came up with, if you are not capable of understanding it then you have no business making ANY kind of decision involving money PERIOD.

I guess if a dollar spent doesn't equate to a dollar spent in your mind after it has been spent then there's no point in arguing cost with you. I think Congress ascribes to your special kind of economic brilliance.

Impaler wrote:

Frankly your arguments have been one of poorer defenses of NTR that I have seen on this forum. Other NTR proponents at least know something about SEP, and stick to basic NERVA types systems without going into fantasy land Gass-Core stuff. This entire thread has been pearls-before-swine waste of my time as it seems every NTR advocate has a cranium capable of shielding them from not only from deadly neutron radiation but facts and reason as well.

Frankly, you haven't provided any logically consistent arguments for why we should not develop nuclear propulsion technology other than the fact that it will cost money and be difficult.

SEP works well between Venus and Mars. Nuclear power doesn't limit our exploration to that area. Long term thinking here.

Nobody forces you to post here. If it's a waste of your time, you can stop posting whenever you wish.

Impaler wrote:

Fortunately NASA make the right choice in the 1990's to commit to SEP and to drop Nuclear like bag of kittens into a river, we have been on that development track now for 20 years and it's an unstoppable freight train of fruitful development that is not going to stop. Instead it is going to open the solar-system to larger and larger probes and eventually manned missions BLEO. But I expect even THEN dolts on this forum will still be pining their hearts away on Nuclear fantasies.

Pinning your hopes to SEP fantasies won't make the technology any more suitable for expanded manned space exploration, either.

Terraformer · 2015-02-01 06:19:32

Wut? If I have a budget of $2000 to spend, and something comes up that will cost me $500, I don't care if someone else spent $2000 on getting it to that point that it costs me $500; I'm only interested in whether it fits in my budget. If something else comes up that will cost me $2000 for the same capability, then I'm not going to choose that just because it's $2k vs. $2.5k; I'm interested in what it costs *me*.

Sure, I'd like to see a nuclear rocket developed, but at the moment and for the foreseeable future it's politically infeasible. The government won't develop it, the public won't support it, and private companies wouldn't be allowed to develop it even if they want to. So any plan relying on nuclear rockets to work is doomed to failure.

SpaceNut · 2015-02-01 11:37:33

kbd512 and Impaler it looks like to me that the disagree to agree comes back to the engine for Nuclear vs Solar if power levels and mass are comperable for each source but not of funding or maturity of readiness.

That said can we get back to the Beoing plan details as to what does not make the grade....please.

From first post:

So whats wrong here?

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