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Comment: Re:Yeah! (Score 1) 102

by Brett Buck (#48950255) Attached to: NASA Looking At Nuclear Thermal Rockets To Explore the Solar System

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.

Comment: Ion Thruster (Score 4, Informative) 102

by Brett Buck (#48949251) Attached to: NASA Looking At Nuclear Thermal Rockets To Explore the Solar System

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.

Comment: Re:Have the Germans threaten to invade (Score 4, Informative) 699

by Brett Buck (#48548679) Attached to: French Publishers Prepare Lawsuit Against Adblock Plus

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.

Comment: Re:the evils of Political Correctness (Score 3, Insightful) 201

by Brett Buck (#48544261) Attached to: James Watson's Nobel Medal Sells For $4.1 Million

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.

 

Comment: Re:the evils of Political Correctness (Score 3, Insightful) 201

by Brett Buck (#48543899) Attached to: James Watson's Nobel Medal Sells For $4.1 Million

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)".

Comment: There's a reason... (Score 1) 368

by Brett Buck (#48543273) Attached to: Overly Familiar Sci-Fi

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.

Comment: Re:Chronology from TFA (Score 1) 77

by Brett Buck (#48543223) Attached to: Pluto-Bound Spacecraft Ends Hibernation To Start Mission

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.

Comment: Re:Spare me NASA's PR Hype (Score 2) 140

by Brett Buck (#48535641) Attached to: NASA's Orion Capsule Reaches Orbit

I agree that the OP is not getting it right but that is not the case. In fact, there were numerous Apollo-related unmanned test flights before the fire, and there were several planned after the nominal launch of AS-204 (renamed Apollo 1 later). In particular, what was later termed Apollo 4 was always planned to be an unmanned mission, as was 6. The only mission definition changes were to remove all the Block I CSM missions in favor of the Block II (which was already in planning, but were also altered due to the findings in the fire investigation) and the launch of the Apollo 5 which originally was intended to go on a manned Saturn V launch but instead was put as a LM-solo mission (obviously unmanned) mission on the Saturn 1b previously assigned to the mission that caught fire. Some other missions, particularly which LM abort cases needed to be run, were still undefined but they were always manned.

Comment: Re:Spare me NASA's PR Hype (Score 2) 140

by Brett Buck (#48533407) Attached to: NASA's Orion Capsule Reaches Orbit

It's "eerily similar" because they are testing the same test points they did before. The fact that a previous spacecraft built with 50's aerospace technology managed to do it doesn't mean that much. We know what to expect, but you still have to actually build what you are planning to fly, and then fly it and see. You can't just simulate everything, assume the simulation is correct, and then shoot it off with 3 people in it on national TV.

      In many ways, the added complexity made possible by much more computing power might be a liability in some ways. Radiation doesn't hurt a toggle switch.
   

"Everything should be made as simple as possible, but not simpler." -- Albert Einstein

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