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And where did you find them? Regan's bogus Star Wars project did generate a little public data on nuclear bombs going off in space. IIRR most of the energy comes out in hard X-rays and fast-moving nucleons. Neither of them is going to get very far into the asteroid surface, so what they would produce would be a very thin, very hot, plasma - lots of energy density but very little mass and very little momentum.

You aren't interested in energy deposition - as such - but in generating momentum. An order of magnitude change in very little momentum is still very little momentum.

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Why would you use a drill pipe? You are working in a vacuum, and anything that gets hot enough to volatilise isn't going to need drilling fluid to carry it away.

We are talking about earth-orbit-crossing asteroids, so a Mylar mirror could concentrate a lot of sunlight onto the place where you want a hole, and boil off anything you are likely to want to get through.

It won't be a pretty hole - more like a conical pit - and you'd probably have to put a tamper on top of your bomb to get the effect you wanted.

You can't, so you are going to have to look at the fragments for long enough to make sure that none of them are going to hit the earth - and administer follow-up treatment to anything that was still likely to hit the earth.

Of course, you might not need a nuke. Getting a billion tons of rock to move at a millimetre a second only requires about a megajoule of energy. Nuclear bombs range from about 100 terajoulse (25 kiloton TNT) to about 200,000 terajoules (50 megaton). It doesn't make much sense to use one when half a pound of TNT - in the right place - could do the job.

-- Bill Sloman, Nijmegen

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I looked up some basics and did some math. I can do that, bacause I'm an engineer.

Regan's bogus Star Wars project did

The thinner the absorption layer, the more momentum is blown off. That should be obvious. A slushball would be worst-case, as the gammas and neutrons would penetrate deep and spread the thermal spike, a problem or a likely spinning object. Something like an iron ball (which you propose to drill into) would be great, because a very thin layer would be turned into plasma and escape at high velocity.

Do the numbers. It isn't hard.

Halfway into a kilometer-sized ball of rock or iron? That is about as idiotic a thing as you have ever said.

The conversion efficiency of a TNT explosion to moving an asteroid at mms/second would be preposterously low.

Cash for clunkers was the broken-window theory in action. Destroy working vehicles, and seize up their engines, to create prosperity.

He'd want to wind a coil out of it first.

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Companies are going to rent time and astronauts on ISS, do research, and NASA isn't going to know what happened?

That's ludicrous. It's way more likely they we haven't heard of any big successes from microgravity research because there aren't any.

Imagine if all those billions of dollars had been spent on earth-bound science. And all those aerospace engineers had done something useful.

It was *so* progressive, too. Make sure those vehicles the "poor" could afford are permanently taken out of the pool.

And leave dangerous, older junkers on the road because their replacements had been destroyed.

Without spam in the can failure _is_ an option. "It is all fun and games until someone looses an eye. Then it is just fun".

More importantly to me personally is that manned spaceflight enabled RA Heinlein to write for a decade longer.

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I always ask these guys why we shouldn't burn down our houses too-- that would create even more jobs and more prosperity. Or sometimes I suggest we should burn down their house--for the common good, of course.

They don't understand wealth, or add in cost, only tally benefit ("The glazier got a check!"). So, their "investments" fail.

Yep. It wiped out the used car stock, spiking prices to the stratosphere. Still. Too bad. My Acura's not going to last forever. Not that big a deal for me, but very unhelpful for the people barely scraping by.

-- Cheers, James Arthur

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Not in detail and not the implications.

It's certainly the simplest hypothesis. That doesn't make it true, or even all that likely. Companies are going to rent time on the ISS because they expect to learn something useful. They are going to be disappointed most of the time - research tends to produce a lot of null results - but there are eventually going to be at least some pay- offs.

Quite a lot of money was spent on earth bound science since the ISS went into orbit. Can you tell me what their big successes have been?

It's not as if Higg's particle has recently been used to do anything useful.

-- Bill Sloman, Nijmegen

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You quite obviously haven't looked up any numbers or done any math.

The thinner the absorption layer, the less mass is blown off and the the more energy goes into that reduced mass and the faster it ends up moving. Momentum is mass times velocity, energy is mass times velocity squared, so moving a small mas fast is the last thing you want to do.

The neutrons generated don't carry much of the energy. I wrote "nucleons" not "neutrons" - uranium fissions to two fragments of about half the atomic number, both travelling very rapidly and emits some gamma rays - hard X-rays - as well as a few neutrons in the process.

There'd be be no practical difference between a slushball and iron ball. In each case a thin surface layer would turn into plasma, which

- as a soup of charged particles - would then absorb both X-rays and fast moving atomic nuclei very effectively, blocking further energy transfer deeper into the asteroid. The neutrons wouldn't be strongly absorbed, but they don't carry much of the energy.

A thin layer escaping at a very high velocity is the last thing you want; momentum per unit energy is at a minimum with a small mass moving very fast.

Obviously you haven't because you don't get the implication of the linear dependence of momentum on velocity and the square law dependence of energy on velocity.

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Do the math. A solar-sail sized mirror at an earth-orbit distance from the sun can capture and focus a lot of energy into a rather narrow compass. It's been proposed as a feasible means for terraforming asteroids into human-habitable structures.

Something cruder, like drilling a deep hole, seems a lot more feasible. It would be a bit tricky for a robot being controlled from a hundred million miles a way, less tricky with more local control.

Not if it was bang in the middle, and the explosion was just big enough to split the asteroid into several chunks that each ended up moving at roughly the same small - but sufficient - speed, in more or less opposite directions.

Put the explosive in a notional bag so that the volume of gas produced has to move the several chunks of rock outwards to make a space into which it can expand.

If you tamped the hole well enough the conversion efficiency would become very good. Half a pond of TNT contains enough energy to do the minimum necessary amount of work on an Icarus-sized asteroid.

A nuclear bomb on the right place could be a lot more effective than one exploded at a distance above the surface of the satellite.

A sufficiently large hydraulic jack - my explosive in a notional bag - would be good enough to do the job. krw clsimed that the velocity change you required - over an earth-orbit period - was only a couple of millimetres per second, maybe 200mm/minute or 10 metres per hour, about 100km per year. I foolishly thought he knew what he was talking about - I should have known better.

The earth's diameter is about 12,756.32 kilometers, so you actually need closer to 400mm/sec.

Since energy is mass times velocity squared - 2.9x10^12 kgm for Icarus

- times 0.4m/sec squared - is 0.464 Terajoules, about one kiloton of TNT or 0.5% of a Hiroshima sized - 25kt - atomic bomb. A 50 megaton uranium-jacketed hydrogen bomb, which would be the biggest currently available, offers rather more overkill if you could convert a useful proportion of that the energy into translational energy in the bulk of the broken-up asteroid.

Conservation of momentum does require you to break up the satellite into separate chunks all moving at more or less the same speed, but in different directions. Any chunk that was travelling much faster than the rest would have captured the bulk of the energy, leaving less available to the rest.

Two equal chunks travelling in opposite directions is the simplest example of an adequate solution.

-- Bill Sloman, Nijmegen

Only if I wanted it to oscillate.

-- Bill Sloman, Nijmegen

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No. Does NASA take credit for that? Corelle was introduced by Corning in 1970. The first Shuttle was launched in 1982. Maybe NASA invented the time machine, too.

NASA likes to take credit for teflon, too. PTFE was discovered in

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Velcro, too, however there is reason to claim both. It took NASA (demand) to manufacture it cheaply enough to enter common usage.

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Velcro was invented in 1948. It was in production in the late 1950s. Sure, NASA used it. How much velcro did NASA use, to stimulate mass production?

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Do you have any clue when the shuttle design programs began? Do you know anything about Corning's role in heat shield technology? I have a portable broiler from them from 1973. All stainless prototype. Very few ever made. IR heating. Now the devices are in every outdoor range out there.

A VERY long time AFTER it was conceived of and designs began, not to mention years of research.

Any accelerated object operates on a different time scale than we do while it is in motion. So it is "ahead of" us from that point forward.

It wasn't mass produced until DuPont did it though, so they created a brand name for it, which is all the "term" "Teflon" is. The discovery of the molecule itself had far less impact.

Goddamned retard Larkin strikes again.

MISSING Teflon *may* have caused the short that ignited the combustible elements.

It was Mylar, Velcro, and Kapton that burned, idiot, and it wasn't badly applied. 100% pure Oxygen was badly applied, you stupid f*ck.

Go read your degreaser manual. Try to catch up.

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Dead astronauts, hundreds of billions wasted, and still nobody can identify a useful payback. Even if NASA had something to do with Corelle (did they?), was some ugly kitchenware worth those lives?

Theory?? It's a fallacy, or a parable ( ala Bastiat ). The "broken window theory" is from criminology, that inanimate objects which signal entropy will cause crime. Popular in 1950s film noir.

Sorry for the pedantry, but...

Sure. You bet. Hey, we have nukes. We could just nuke Vegas and start over... just think of the ... prosperity!

-- Les Cargill