This is a pretty facile assessment. The safest possible approach would be to ban the plants entirely. Once you dismiss that, then it's a trade-off.

That's compared to a few hundred pounds for an equivalent chemical rocket. The point of post you are replying to is absolutely correct, it only makes sense if the rocket using it is large and carries a large amount of propellant.

      There are effectively two factors in rocket design - the engine ISP and the mass ratio. The mass ratio is a measure of how much propellant is carried VS the dead weight (engine, tanks, payload). Those two things can tell you the velocity change of the rocket (see: "rocket equation"). Note that you have to recognize that the ISP and exhaust velocity are one and the same to make sense of it.

  The ISP is twice as good as a chemical rocket, but the dead weight is very high, too, so for this to make sense, you need a large amount of propellant. The difference between 250 lbs (chemical rocket weight) and a few thousand (practical lower end of the NTP and associated shielding, etc) could be critical.

    For example, using hydrogen as a working fluid increases the ISP (the lighter the exhaust products, the better) but reduces the mass ratio because the density is so low, the tanks have to be gigantic and therefore heavy. reducing the mass ratio. If it used Xenon, it might have lower ISP but the dead weight would be smaller due to much smaller fuel tanks. It's a trade-off, and NTP engines don't care very much what fuel they use.

    Someone has already figured all this out, there was a perfectly sound design for a rocket upper stage using a NERVA engine, I would suggest that as a point for further research.

In this case, it's absurdly beside the point as well. The expenditure of nuclear materials is utterly irrelevant to the problem.

      The way to rocket works it to use nuclear-generated heat to expand and accelerate a working fluid (usually hydrogen) and shoot it out the nozzle. What matter is the mass of the working fluid expended per impulse (force x time) - the specific impulse (lb-sec/lb or kg-sec/kg, for units of seconds) or ISP. T

      housands and thousands of lbs of the working fluid will be consumed, the fact that it also consume a few ounces of nuclear material, too, is utterly in the noise.

    A very good chemical rocket will have an ISP of 450-460 seconds. A nuclear thermal rocket will have an ISP of around 900-1000, or roughly twice as "good". "Good" is defined by the amount of impulse/momentum change you get for a given amount of fuel consumed.

A nuclear thermal engine can be built to provide almost any desired thrust level, with 25000 lb thrust engines actually built and tested.

      By comparison, a Hall Current or other ion engine will have an ISP of around 1800, but use vast amounts of electrical power for extremely feeble thrust of far less than a pound in typical cases.

Actually, I do get that, and /. is full of them. And they are hopeless - everybody actually doing work is stupid, and the real experts are the guys in various mom's basements who saw 'Empire' 27 times.
  Sometimes, it gets the better of me.

An Ion thruster (of any variety) is not *remotely* a replacement for a nuclear thermal engine. The ISP is great but the thrust levels are (and always will be, at rational sizes) feeble. And it's very likely that massively clustering them to get the thrust up will required a nuclear reactor to power them. 6/10ths of an *ounce* of thrust for 4 kW power input.

Ion thrusters have their uses, like in gently nudging things over long periods. They are not going to replace chemical rocket or NTP engines for any sort of high-thrust application.

Right, the politicians will have to answer some tough questions. Politicians with constituents that work at ULA, in some case, in large numbers.

Too bad there's no "Johnny Dangerously" bonus mod point. Perhaps there should be

The work is meant as a metaphor for showing the battle being waged by Mother Nature on the accelerated development of industrialized civilization."

    Ah, so he's an idiot.

Correct. Then a large fraction of the government capitulated, formed a puppet government, and did the Nazis' bidding, including rounding up people for shipment to concentration camps. And in some cases, like in North Africa, fought (weakly) against the allies.

At the same time, the parts of the government and military that were caught in or escaped to England made themselves royal pains in the ass to the allies, posturing and playing politics to try to claim they were in charge of the government in abstentia, This greatly complicated the invasion planning and led to poor tactical decisions based on maintain the pride of strutting martinets like DeGaulle. This allowed the Germans to escape through the Falaise gap, for example, when they were otherwise going to be caught. This probably extended the war another 6 months.

        The ultimate was in the 60s. DeGaulle demanded that all American tropps be removed from French soil. Lyndon Johnson asked him "does that include the 65000 that died lliberarting it*.

    That's why we hate the French.

I don't care what you say. Say whatever you want, I am a conservative, so I don't think it's a good idea to censor speech.

      Thwe Watson case is an absolutely classic case of PC bullying.

The latter is exactly my point. I would think the man's premise would be quickly and easily refuted. And it was and is.

      But the "community" couldn't let it go at that. He had to be punished for the way he thought, because it made everybody feel better.

You are probably right about the confirmation bias. But one should be able to make that argument without hounding someone out of a profession. That is more-or-less what happened here.

      I would also note that almost no one here is actually a scientist, much less a Nobel prize winner. So no one is all that qualified to debunk his idea. There are certainly falsifiable points in his premise on race (and probably plenty of research to support it). All that need be done is produce and make the argument, and the issue should be closed. But no, that's not sufficient, he has to be punished.

      This is a classic case of claims of "Science!" being used as a cover for political correctness. More like "Science! (so shut the hell up)".

Of course it's a familiar cultural setting. Unless the nature of the culture and social interactions is the theme, you would rather have something that the reader can relate to. You need to relate it to something the reader will understand, because, otherwise, you will either use up inordinate space and words describing it, or leave the entire thing unexplained which loses the reader.

    Moreover, human nature hasn't changed consequentially for 10,000 years. The same motivations, reactions, and through processes are on some level universal. The culture *hasn't* changed all that much at the root level. The means and mechanism, and superficially changes, but deep down nothing is really all that different since the development of "civilization" coincident with the agricultural revolution.

The components were already at the minimum operating temperature. You can't just let everything cool to the background, then hope to heat it back up later. Something will likely break. There have been survival heaters and (in this case) thermal shunts from the RTG to keep it warm enough the entire time.

How the mighty have fallen. First, a Roman god, 2000 years later, you live in a doghouse and take orders (confusingly) from *another dog* - and a dimwitted country hick dog, at that.