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Comment: Re:A large load of sheets from BB&B (Score 1) 149

I'd anticipate significatnt sublimation and thawing on even the backside if the solar sail does not reflect _away_ from the object.

Since at least some comets that cross Earth orbit (and are therefore a threat) have had insignificantly altered orbits for several thousand years and dozens of perihelia, then the lower limit of sublimation you're going to need to consider is under 1% per apparition. Even with a solar sail blasting the backside with essentially another Sun, you're still down in the 2% per apparition or lower range. (I'd guess lower). Comets on a sun-diving orbit are approximately half the threat of ones that don't sun-dive. The sun-divers don't get a second chance to hit the Earth.

But the idea provides far more available thrust and control than draping coverings directly on a tumbling asteroid or comet.

I agree on this point. But since the proposal is for a generic design to deal with any incoming impactor, be it comet, asteroid, or even generation ship, then a design that can handle any impactor without modification is needed. There won't be time to design a modification if it is actually needed.

Comment: Re:North Pole (Score 1) 486

by RockDoctor (#49747853) Attached to: The Brainteaser Elon Musk Asks New SpaceX Engineers

that brain teaser has been around for what, eons now?

I literally (not figuratively) cannot remember when I first heard that one, but I was using it to get a friend's head around spherical geometry in the mid-1980s, so I knew it long before then.

I'd finger Eratosthenes as the guilty party. Or a close contemporary.

Comment: Re:It's about money. (Score 1) 289

by RockDoctor (#49747833) Attached to: North Carolina Still Wants To Block Municipal Broadband

He was lying. [aside]You can tell when politicians do that by checking to see if their lips are moving.[/aside].

What a refreshingly open and honest political culture you have. Here, we can tell when our politicians are lying by their not being decomposing into putrid puddles of greasy bones. The only honest politician is a dead one. Dead and clearly decomposing.

Comment: Re: Sudafed (Score 1) 333

by RockDoctor (#49747817) Attached to: Genetically Engineered Yeast Makes It Possible To Brew Morphine

tasteless hops to make their piss water.

"their diabetic horse's piss", please. Go the whole hog on the (entirely justified) insult.

(The version I'm thinking of is $BIG_MERKIN_BREWERY$ sends crate of it's best product to Czech brewery $BIG_CZ_BRAUERIE$. Some weeks later a reply is recieved at $BIG_MERKIN_BREWERY$, which is opened with excitement : "Dear Sirs. We regret to inform you that your horse has diabetes.")

Comment: Re:The song remains the same (Score 1) 201

by RockDoctor (#49747747) Attached to: Baton Bob Receives $20,000 Settlement For Coerced Facebook Post

The policeman camera is the best reign of all,

From a country (most likely, this being Slashdot) where the reign of monarchs was overthrown by terrorists over two centuries ago, and where the national self-image is as a cowboy clutching the reins of his horse and riding off into the sunset ... I find the inability to distinguish the two homophones particularly hilarious.

And it seems to rapidly be becoming a more common misspelling.

Comment: Re:Get a second ethernet adapter. (Score 1) 375

by RockDoctor (#49747677) Attached to: Ask Slashdot: Best Way To Solve a Unique Networking Issue?
To be honest, I was thinking of a second laptop on a cart, with a bunch of cables hanging out of the back end of it. Possibly four laptops (TFS mentions VMs running XP so any brain-dead 32nd-hand laptop should have the necessary grunt) on a cart so you can do an entire island at a time.

- set out the cones to stop new cars arriving at the target island then hook up the cables as existing drivers finish and leave.

- set upgrade running on first system to be ready. When you're blocking on that pump, swap to starting the process on the next available pump ; lather, rinse, repeat until all 4 are running away.

- meanwhile, start moving the cones so the first machine to be finished will be the first available to the next customer, and you're ready to start isolating the first pump of the next 'island'

If you can spread things out evenly, then your maximum hanging around time has dropped to 7 and a half minutes, and if there is any significant amount of user input, your idle times are going to be shorter than that.

Though it is a networking problem, it's really an optimisation issue.

Comment: Re:A large load of sheets from BB&B (Score 1) 149

by RockDoctor (#49747137) Attached to: Ask Slashdot: Best Payloads For Asteroid Diverter/Killer Mission?

You can get a much, much larger effect by attaching a much larger, more easily manufactured and testable actual solar sail.

How are you going to do that attachment again? The attachment mechanisms for Philae worked spectacularly well given the amount of information that was available about the comet's surface structure ten years before contact. So we can realistically anticipate a similarly accurate degree of knowledge about the surface properties of the asteroid we need to manage in two years time.

Next suggestion?

Comment: Re:The issue isn't worth fighting over (Score 1) 293

Further to Itzly's reply, nor are there any volcanoes anywhere near the Larson B ice shelf. There are probably sub-glacial volcanoes in the hinterland of some of the more southerly ice fields and sheets of West Antarctica, but from the absence of ash bands in the surrounding ice cores, they're pretty marginal on the activity front.

Oh, BTW, we know from studies of Icelandic volcanoes that even quite minor sub-glacial eruptions tend to produce substantial amounts of ash because of the violent emission of steam from interactions between lava and ice.

Your hypothesis is superficially reasonable but is destroyed utterly by the facts of the situation.

Comment: Why care (Score 1) 167

by RockDoctor (#49713727) Attached to: How Spotify Can Become Profitable

but it can become profitable with some specific changes according to one analyst.

So, another attempt to get rich on music falls flat on it's face, burning it;s investors arses in the process. And why should anyone care? If we believe the bullshitters, the entire music industry needs to die so that people can pay musicians directly, instead of letting the money be stolen by the music industry.

Well, that'll be great. And if the music industry goes down the shitter and takes the musicians with it, who's going to care?

Comment: Re:And what of false positives? (Score 1) 94

by RockDoctor (#49673089) Attached to: Can Earthquakes Be Predicted Algorithmically?

Any seasoned geologist can do that these days, we've known about earthquake predictors for quite some time and given the measurements,

Citation required.

If this is true (which I strongly doubt) then the geological press would be more full of it than if NASA launched a faster-then-light space ship and came back with a pointy-eared Buddha. Because there has already been a Buddha, but an effective earthquake prediction methodology would be something startlingly new.

Citation required. Journal name, volume and page number.

Comment: Re:Lists (Score 2) 94

by RockDoctor (#49673041) Attached to: Can Earthquakes Be Predicted Algorithmically?

I don't know if they stated those predictions in public.

If it's not stated in public, then it is not worth the 30-m high letters in which it wasn't painted on the side of a building in down town Geneva.

Actually, there is a fair point there : there is no recognised forum for posting such predictions. And there are a lot of internet kooks out there who all think that they've got the perfect solution, but not one of them is willing to stand by a "prediction".

Some ground rules have been proposed about what constitutes a prediction. And then the kooks get involved and turn it into a kitten-in-a-washing-machine-with-a-broken-bottle experience for anyone who is in the least bit serious. Little things like : the prediction should be specific with respect to period to which it applies, magnitude of the earthquake predicted, and region that the prediction covers ; secondly, the prediction should be sufficiently precise that the pre-existing records for the area concerned would not predict that event just on statistics. "A magnitude 4.0 in southern California in the next 6 months" isn't a prediction, it's a racing certainty. "A magnitude 5.0 + on the eastern English Channel within the next 6 weeks" is a prediction (there was such an even in the late 17th century, IIRC, and hasn't been one since. So the occurrence of a predicted earthquake there would be pretty remarkable.) And finally, ALL your predictions need to be made public, and your method will be judged on the results of ALL of your predictions. (Some of the kooks use the "predict everything, everywhere, all the time" approach, and think that is effective.Your failed predictions will be counted along with your successes.)

Even getting agreement on these basic points - it's the kitten and the bottle into the washing machine again.

While all geological services are interested in such questions (including the BGS, in whose balliwick the Channel quake mentioned above falls), none of them see any reason for any general system to work. Why? Because they're geologists. As am I. So I can explain why they don't expect a generic system to work:

An earthquake occurs in a natural material which is inhomogeneous - in fact it has a structure that varies on scales ranging from the sub-millimetre to the multiple kilometre (I work at the sub-millimetre to sub-centimetre scale - people pay me to describe that inhomogeneity). The strength of such materials can be predicted in compression reasonably well - to within 20 to 50% ; but not so well in tension ; shear, combining tension, compression and structural homogeneity (absent - see above) is rather more difficult still. Earthquakes can occur because of either tension, compression or shear ; most often shear since it combines the others. Moving from the materials in which the failure occurs, consider the forces involved. They are, oddly enough, variable, because the distribution of forces depends on the action of large scale forces (weight, plate movements, tides, weather (including the last few centuries of rainfall and the last few minutes of barometric pressure)) which are delivered to the rock units that fail by a cascade of intermediate units, each one of which varies in stiffness (Young's modulus, for starters), in it's time variance of behaviour (some rocks "creep", others don't ; look up pictures of "chocolate boudinage", if you want to get a handle on how much rocks can vary) .. oh, and did I mention that the properties vary on scales form sub-millimetre to multiple kilometre?

So, how are we going to attack the problem. Clearly we need to map the rocks and the forces. But there is a problem. You see, rocks are generally opaque. Opaque to visible light ; opaque to anything with a shorter wavelength (and therefore able to measure the small scale variations), unless you can get the rock into a synchrotron beam or industrial X-ray machine. And them do the same for the next couple of millimetres, and then the next ... and finally put it back together again without leaving cracks in it (which will change the rock's response to forces, and it's transmission of forces).

What about longer wavelengths? Well, here we do have some hopes : acoustic energy. It'll pick up variations in mechanical properties on a scale of half the wavelength of the sound used. It's called "seismic". I use it a lot at work. Of course, some countries ban it because it fucks whales ears (we employ a dedicated Marine Mammal Observer when we have guns in the water). And the really interesting high-frequency waves ... err, they interact with the rock and are absorbed. So the further you get from the sound source, the coarser the information that you get back. In practice, at the geologically interesting depths of a handful of kilometres, we simply cannot see a fracture of less than about 10 metres in height.

People are trying to get around the problem of seeing through rock. Oil companies in particular (which you won't be surprised to learn, is my trade). It is a multiple billion dollar industry. And it is far, far, far below the resolution that is necessary.

Just as a matter of interest, what are your proposals for measuring the state of forces in the rocks under your feet? That is, measuring the forces, not speculating about them.

The above are the main reasons why national geological services do not waste their tax-payer-provided funds on earthquake prediction research. The payback from the same money on building protection and emergency response has a far, far better return.

On the other hand, feel free to develop your own proposed methodology. Then you too can get involved with the kooks (I'm not calling you a kook ; everyone else is a kook. They all agree on that!) and post your predictions on an appropriate forum. And IF your predictions work better than chance (your statistics had better be good ; remember Feynman's dictum about fooling yourself ; he meant it to apply to himself, and I'm reasonably sure that you're not much better a scientist than Feynman) then there will be people beating your door down to buy into your method.

Don't expect me to invest.

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