DerekL1963

Keep in mind that the current state of development for the NSWR is... essentially non existent. Zubrin's paper barely reaches the level of "back of the envelope" and no serious analysis has been performed by anyone who knows what they're talking about. Nobody has any idea if it will actually work.

Water in space is virtually valueless - because there's no virtually demand for water in space. (For those of who don't grasp basic economics, something is only worth what somebody will pay you for it.) Not to mention, if you read what I was replying to, the individual specified "on Earth", which implies returning the material to earth. And it's ludicrous to say that because we've only been looking for materials for scientific reasons that we can't then turn around and compare the value of what we know to be out there against the costs of recovering and transporting it. (Not to mention, Planetary Resources isn't looking for materials - they're looking for mining sites, something they can only do because we already know what materials are out there.) And no Albert, I didn't miss part of what you said - I showed how the whole of what you (and others) are saying is deeply flawed. That there is a difference difference between theoretical and actual. No form of actual terrestrial transport had to create destinations - and thus the theoretical "space-travel-as-terrestrial-transport" model is broken right out of the gate because the two have nothing to do with each other. Cars and planes and boats developed because there were tangible economic benefits to doing so. Space travel isn't, because there are no such tangible benefits. Nobody here is "against" space development. But only a couple of us can tell the difference between engineering and economic reality and the cargo cult dogma that characterizes the average "supporter" of space development.

No, it's not at all hard to say once you look at actual numbers. There's no material on Earth that you wouldn't go broke fetching back from space, even if it were already refined and neatly packaged so that all you had to do is pick it up and stack it in your return vehicle. None. Zip. Nada. Huh? People are looking very, very intensely at what materials are in space - because examining those materials are basic to answering the scientific questions we send stuff into space to answer. That's where the space-as-new-world model breaks down, space isn't Terra Incognita. (And old thread is old, just as here - it's people trying to replace cold hard facts with optimistic assumptions, wishful thinking, and vague handwaving in order to reach the predetermined conclusion that space is the place to be baby.) What Nibb was trying to say and the point you (and many others) are missing, is that the growth of terrestrial travel was fueled by actual destinations, not theoretical ones. By actual economic advantages, not wishful thinking.

That's the problem with both the space-as-aviation model (there's nobody there and no place to go), and the space-as-the-New-World model (there's nothing there worth bringing back). There's just no demand for going there, and launch costs keep it that way. Launch cost really have to fall until they're relatively small multiple of the energy cost until either model can even begin to be relevant, and even SpaceX's most fervent dreams result in costs that are still several orders of magnitude higher than energy costs.

We're wandering far off topic, but Stargate is quite correct - In 1936 (as in 1914) America was largely isolationist, moderately pro-German and (in the eyes of the general public) not necessarily that fond of the British. (Not to mention there was still lingering feelings of antipathy that dated back to the Revolution.) In both wars it was a combination of a largely anglophilic (American) upper crust and German over aggressiveness that ended up tipping the balance and causing events to unfold as they did.

"Going to the moon anyways" isn't in the plan...

Then nor now, Popular Mechanics has never had a reputation for honesty or accuracy. They're not quite a tabloid when it comes to such things, but they sure as heck have shaved awful close over the years.

Spending 10 billion to save 50 or (at the way outside) 100 million a flight... makes sense, how exactly? That's point of my original post, we don't fly enough (by an order of magnitude or more) for the economics to pencil out - the missions end up "far cheaper" only if you handwave away the actual costs of the "cheap" fuel. That's been the deep flaw in all the "fuel depot" studies to date - the "savings" only materialize via dodgy accounting.

Ayup. In the same vein, even if the handwavy parts work - the colony only "pays for itself" (becomes "economically viable") if someone ponies up the cash (to the tune of probably ten plus billion USD a year) to fund the missions to use up the mined hydrogen.

Why wouldn't you consider Trident II "modern"? Why is "modern" even relevant in the first place? Missiles (like pretty much all real world equipment) aren't the latest iShiny, nor are they like your computer which eventually won't run "modern" software. Shake yourself free of the cultural bias towards the newest and improvedest and shift to a dispassionate engineering point of view - where things are judged by absolute performance, not by relative age or whether or not they're fashionable. That being said, you've even got the age of the design wrong. The guidance system has already been updated once, and they're fixing to roll out a new one this year. The fire control, navigation, and key elements of the ship system* have all been upgraded multiple times over the years. There's also a re-motoring program that should get rolling in the next few years. The Trident II system out punching holes in the ocean (as we say in the SSBN force) isn't the one that came off the assembly line back in the 90's, there's been a continuous program of upgrades and enhancements. * Trident II is a weapons system, and you really should consider the functionality of the system as a whole rather than focusing myopically on one component.

Those are response times, the time from detection of the vehicle to impact. Actual flight time is going to be somewhat longer, moderately in the case of direct IR detection (such as the DSP satellites), potentially much longer in the case of early warning radars (where the satellite must rise over the radar horizon before it can be detected). Figure 65, on the next page of the book you link, clearly illustrates that difference. That's an orbital trajectory, suborbital (missile attack) flight times will be longer. (Because that flight time of a suborbital missile strike includes the launch phase, during much of which the missile's velocity is much lower than it's final velocity). Anyhow, as I said above, actual flight time (tube-to-target) is going to vary with range and with the trajectory selected. You can't give an approximation of any value without knowing the range.

0.o Nobody sane would ever try this plan, and someone insane is even less likely to try it because it places the weapons out of close control and leaves them in insecure areas, and vastly increases the chances of them being discovered and intercepted. There's a reason why pretty much everybody who has ever seriously tried to build a nuclear weapon has also chased (and generally obtained) at least IRBM capability. (The sole exception is South Africa, but there were special circumstances there.)

The Soviets made patrols in the Atlantic at least as late as the mid 80's, because their earlier missiles could not reach useful targets in the US from the Barents or White seas. Only the later generation SSBN's and missiles, which could reach the US from areas near the Soviet coast, were deployed in bastions. In fact, as the cold war wore on, they tended to deploy less and less (Soviet SSBN patrols are generally accepted to have peaked in 1983 and declined sharply thereafter) instead relying on a 'surge' strategy in times of crisis. Given their current status, it's not clear that the Russians are deploying their SSBN's that often, and nor does it appear they can defend them adequately. The Chinese are not currently known to have ever actually deployed their SSBN's, nor are their missiles known to be operational. There's a lot of rumors and grave pronouncements of potential capability from US officials, but nothing firm from either side. The eastern Atlantic does not, in the naval sense, constitute a bastion. There's not known to be any defenses or standing defensive patrols or sensor networks. It's highly likely there are cooperative efforts in tracking potential hostiles and in conducting delousing operations, but that's not the same as a bastion.

That depends mostly on the range, and to a lesser degree on the trajectory chosen. Full disclosure: Trident-I Missile Fire Control Technician, USS Henry L. Stimson (SSBN 655B) 1983-'87.

This bears quoting for emphasis - there's a lot of talk about electric propulsion and especially about VASIMR... but few people really seem to grasp just how much power they require to be any kind of useful. And power supplies are heavy. Electric propulsion isn't a way around the brutality of the rocket equation (despite their seductively huge ISP), and in some ways it's worse than chemical propulsion because you don't get the performance boost that chemically propelled vehicles do as they burn off their fuel supply.

I can't speak to the Chair Farce, but the guys who've developed (IIRC) three generations of guidance systems for the Trident II (the most recent started deployment in 2014) will be very surprised to learn this.

Yep. And interestingly enough, the 'sweet spot' between deliverability, yield, and usefulness for the West seems to be down in the 300-400 kiloton range (though some are smaller still). (The Russians seem to prefer weapons more in the 700kt-1mt range.) Though the US built and deployed a number of multi-megaton horrors during the 50's, the average yield of strategic weapons dropped sharply in the 60's and 70's. Between these lower yields and the possibilities of boosted fission, and because Teller-Ulam can drive a lightweight and extraordinarily efficient pure fission* or boosted fission secondary as easily as it does a fusion secondary... there's a school of thought that questions whether the US actually has any "true" (Teller-Ulam, fission-fusion-fission) thermonuclear weapons in it's inventory. * What eventually became Teller-Ulam in fact started as a method of using a fission primary to drive the implosion of fission secondary.

The DOE is producing tritium for something. Three guesses what it is, and two of them don't count. According to this (PDF link), tritium is associated with the W76 and W88 (Trident II) weapons, the W78 and W87 (Minuteman III) weapons, as well as the W80 (ALCM and Tomahawk) and the B61 (gravity bomb). Tritium allow you to easily build dial-a-yield weapons. It also (and unlike lithium deuteride) enhances nuclear safety because it remains isolated from the pit unless specifically injected.

Spot cooling is still somewhat useful for LV-N powered designs.

What you describe won't actually work - in order to fuse, the fusion fuel has to be compressed. Even a thermonuclear weapon doesn't generally generate enough heat to force fusion in an uncompressed fuel mass. The solution to that problem was the staged Teller-Ulam configuration. (There does exist a middle configuration between pure fission and Teller-Ulam thermonuclears, the boosted fission configuration, but explaining that... would require more background material than I care to type.) As to how to create a "clean" (minimal fallout) weapon, see sections 4.5.2 ("Dirty" and "Clean" Weapons) and 4.5.4 (Minimum Residual Radiation (MRR or "Clean") Designs) of the Nuclear Weapons FAQ. (Warning: serious science/physics content.)

On top of having one of the most confusing and user unfriendly user interfaces in all of creation... the fact that it's a popularity contest. Flow with the groupthink, or be downvoted into oblivion.

Umm... we were using that term, or some variant thereof, in space discussions on Usenet back in the 90's.

FWIW - when I was in the Navy, I encountered spares that had gone bad (insulation failing, capacitors failing, etc... etc...) that were as little as fifteen years old. Seriously, drag is easy enough to overcome (just put your orbit high enough) and damage from dust/pebbles/debris is (other than a 'golden bullet') only a worry on the time scale of centuries. Power, radiation damage to electronics, atmosphere control, degradation of plastics, etc... are much higher on the list.

Greetings! Is there a 1.0.4 version in the works? The version of KSPAPIE you're using is not compatible. Thanks!

I'm a fan of this option.