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Interviews: Ask Engineer and L5 Society Cofounder Keith Henson a Question
Keith Henson is an electrical engineer and writer on space engineering, space law, cryonics, and evolutionary psychology. He co-founded the L5 society in 1975, which sought to promote space colonization. In addition to being an outspoken critic and target of the Church of Scientology, Keith has recently been working on the design of an orbiting power satellite (video here). The proposed satellite would collect solar energy, send it to Earth via microwaves, and Henson has a plan on how to launch it cheaply. Keith has agreed to give us some of his time and answer any questions you might have. As usual, ask as many as you'd like, but please, one question per post.
If the beam becomes misaligned and strikes Iowa, how do you stop the entire state from exploding into a massive popcorn volcano?
I was born three years earlier than this project and that's the first time I ever hear about it.
Leaving aside the not insignificant economic and safety concerns, I'm interested in the technical feasibility of extracting minerals from asteroids in useful quantities. On earth, we extract minerals concentrated by geological and biological processes that are unlikely to have occurred on an inert asteroid.
What do we know about the distribution of minerals within asteroids, what more do we need to know in order to design machines that can extract these minerals, and what can you speculate about how those machines might work?
Thank you!
We don't have a state-run media we have a media-run state.
What is the cost per KW for the build/deployment and resultant cost per KWh for the end user?
because none of the top coal mining states are Democrat, like say West Virginia or Kentucky? You're an idiot
Keith can give you the accurate and current story on it.
But as I recall it (from the proposals in the early days of the L5 society and some experience with microwave and synthetic aperture techniques):
The powersat has many transmitters. Each single transmitter, even with a very directional antenna, puts out a very wide beam. (It might cover the whole face of the planet (and beyond)). One transmitter would look more like a radar transmitter at least (26,199 - 3,959) = 22,240 miles away - about 9 times the distance from New York to Los Angeles.
The transmitter/antenna devices distributed across the platform are phase-synchronized by a pilot signal transmitted from the ground rectenna site. They compute the complex conjugate of the (equivelnt at their frequency) signal they receive and transmit that. This orchestrates them so they form a beam that retraces the path through space, correcting for flexing of the powersat structure, the turbulence of the atmosphere, clouds, aircraft - metal, wood, or feathered - rainstorms, ionospheric distortions, etc. and focuses on the pilot transmitting antenna(s), like a hologram.
A number of factors defocus the beam somewhat, so you get a spot that covers the rectenna efficiently rather than tightly focussed on the pilot transmitting antenna(s), or leaking all over the surrounding county. The main one is the diffraction limit at the frequency involved, given the size of the transmitting array and distance from it: The bigger the transmitting array, the more tightly focussed the spot on the rectenna site can be. You don't want it TOO tight, to keep the power density reasonable (like a few times sunlight's power density). But the battle is to get it tight enough so your rectenna farm isn't city-sized, not to keep it from being too tight.
If pilot lock is lost by a single transmitter, it no longer stays locked to the rest of them - its signal spreads out like that of any lone transmitter. It stops contributing to the power in the rectenna and "shines" on the whole face of the planet - becoming microwave background noise. If pilot lock fails completely, all the transmitters VERY quickly go out of sync with each other (and can be deliberately given individual drift rates to insure this happens quickly). They ALL shine, incoherently, all over the world. All the power spreads out over the whole face of the planet and beyond. That part of the sky gets loud in microwaves, so you don't want to park a commsat there. But it's not going to toast Tokyo, or cause malfunctions in old-style pacemakers in Cleveland.
Of course you can design the transmitters so any that doesn't have pilot lock just shut down, if the solar array can accept the loss of the load. You can also modulate the pilot with a cryptographic identifier, to keep people from stealing power - or warming Central Park slightly - by setting up a second pilot transmitter at another site and making the "hologram" deliver a second spot.
Meanwhile you're not going to have roast birds falling out of the sky (like you do with the point-focus solar power systems). Microwave ovens cook because they use a frequency that is strongly absorbed by water. Milimeter-wave power systems use a frequency that is chosen to NOT be strongly absorbed by water. This lets it go THROUGH clouds, and birds, rather than being absorbed and heating them. They're not PERFECTLY transparent to it. But at the frequencies and power levels involved at the best focus you can get it's more like having an incandescent lamp in the room than like being in a microwave oven.
Meanwhile the rectenna is spidery enough that most of the sunlight passes through it, and efficient enough that most of the power does not. You can put it up on poles and graze cattle under it, without cooking the cows or the grass.
Bantam Dominique roosters crow a four-note song. Once you've heard it as "Happy BIRTHday" you can't NOT hear it that way
Most of us on slashdot will probably agree that "Economics, Energy, Carbon and Climate" are all one big problem that needs more investment. But the devil is in the details of how to do it.
I'm not an expert on this subject like Henson, but IMHO a space elevator seems just as close to being technically viable as space plane powered by a ground-based laser and microwave power beamed to earth.
Not only that -- a space elevator would be much cleaner and the cables might even be able to double as power transmission lines.
And -- since all the good tethering points are in the third world (the equator) it would be a big solution to economic disparities too.
Why does Henson's article not consider the possibility of a space elevator ?
You forgot a third type of Republican: the conservative Republican.
Conservative as in they are for conservation, not because they're prudes who are against short skirts or raunchy behavior. Theodore Roosevelt was the model conservationist republican.
Basically these are people who like the things they had in their lives and want to conserve them for future generations. This includes their society, culture, and the environment.
In recent times they have lost power to Establishment republicans who favor big business above everything else, but back in the day Teddy would establish National Parks and limit development to preserve nature and tell Standard Oil to go fondle itself.
The key thing about them is that they had a happy childhood. As opposed to some politicians who had such a negative experience with their own upbringing that they want to "fundamentally change America".
Did NASA get through the firmament? Why can't anyone go to Antarctica? The edges seem to have been closed off around the same time (late 1950s).
I feel fantastic, and I'm still alive.
Conservative as in they are for conservation, not because they're prudes who are against short skirts or raunchy behavior. Theodore Roosevelt was the model conservationist republican.
Basically these are people who like the things they had in their lives and want to conserve them for future generations. This includes their society, culture, and the environment.
Make up your mind, which is it? They aren't prudes, or they want to keep society and culture at a standstill.
"You're right," Fisheye says. "I should have set it on 'whip' or 'chop.'"
Basically, there's two kinds of Republicans:...
That only describes the lunatic fringe, kind of like saying all Democrats were out on Wall Street blocking traffic.
The other 95% of Republicans are as close to the center as most Democrats, albeit fiscally a bit more conservative, socially not quite as enthusiastic about entitlement programs, and are open to discussions of responsible energy policy.
You seem to get to a similar place as O'Neill did in "The High Frontier" -- only without the inspirational Bernal Sphere to Stanford Torus to O'Neill Cylinder progression. I hope you still see those as real opportunities.
If nothing else, this post was awesome for directing me to "Home, home on Lagrange"
Oh, give me a locus where the gravitons focus Where the three-body problem is solved, Where the microwaves play down at three degrees K, And the cold virus never evolved. (chorus)
We eat algae pie, our vacuum is high, Our ball bearings are perfectly round. Our horizon is curved, our warheads are MIRVed, And a kilogram weighs half a pound. (chorus)
If we run out of space for our burgeoning race No more Lebensraum left for the Mensch When we're ready to start, we can take Mars apart, If we just find a big enough wrench. (chorus)
I'm sick of this place, it's just McDonald's in space, And living up here is a bore. Tell the shiggies, "Don't cry," they can kiss me goodbye 'Cause I'm moving next week to L4! (chorus)
CHORUS: Home, home on LaGrange, Where the space debris always collects, We possess, so it seems, two of Man's greatest dreams: Solar power and zero-gee sex.
It's like the entire 70's were just ahead of their time.
So, whatever happened to the scientology thing, anyway? I remember reading about what was going on, but I never really heard how it all came out.
We've learned a lot since the rather naive plans of the 1970s, when space colonization was first proposed by Gerard O'Neill and his students.
How are things different now? What's the most important thing we've learned since then?
http://www.geoffreylandis.com
What's new in the way of freezing dead people? We heard a lot about this several decades back, but the idea doesn't make the news any more. Still a viable concept?
As the Libertarian Party itself says, there's more than one axis for political thought; according to them, there's economic versus social axes. The "libertarians" in the Democratic camp aren't really libertarian, they're only libertarian on social issues (I'm like this). Basically, they think you should be able to smoke pot, marry whoever you want, etc., but when it comes to corporations and the environment, they want a lot more regulation. Real libertarians want very minimal (if any) regulation of corporations, environmental issues, etc., as well as no regulation of social issues. Classic Republicans want all kinds of regulation on social issues (reproductive rights, who you can marry, who you can have sex with, drug laws, etc.), but not so much regulation on corporations.
Oh please. Those Republicans haven't been around since the Democrats were the party of the KKK. The parties have completely switched places in the last 50 years or less. That's why the party of Lincoln and Teddy is now the party of racism and big business, whereas what used to be the party of Andrew Jackson (Mr. Trail of Tears) and the South is now the party that tries to claim it's for environmentalism and diversity.
That's BS; if it were true, the entire panel of Republican primary contestants wouldn't be from the "lunatic fringe". Unless there's a bit of truth to your statements and that's why Trump is so popular....
QA, there are so many bizarre assumptions and bad arguments in that link, such as assuming we can't both solve problems on Earth and do space stuff. Or throwing in some irrelevant rant about the impossibility of forever exponentially increasing energy consumption (which isn't needed for anything). Or the bizarre distance argument about difficulty of reaching some location being somehow proportional to its distance from Earth rather delta v or availability of energy/resources at the destination. And of course, there's the argument that because space is bad for naked people, then we can't possibly go there.
There are some on the fringe. But one could say the same about the Democrats (I hope you don't consider Hillary and Sanders main stream).
Trump is only popular with Democrats who say they're Republicans when they respond to a poll. Their only hope for the White House this time is to get him to run against Clinton, but I don't expect either to get the nomination
If that's true he has some explaining to do.
"Bizarre assumptions" is Space Nutter code for physics, reality, and limits.
Nothing will happen in space. Ever.
We already know that technology allows us to do a whole lot more in space than "nothing". That's already demonstrated to be false. Why argue that we can't live in space or other such things when there's been people living in space for over 15 years and profitable and useful satellites?
And the rapid advance of technology these days rules out that things will stay as they are forever. Just because it's relatively expensive now to put things in space and as a result do useful things in space, doesn't mean it will always stay that way. It just doesn't take that much physically to put things in orbit. Energy is extremely cheap and reaction mass for delta-v is only about an order of magnitude more expensive. The physics just isn't in the way.
Could you give a general overview of what the wear factors are for your system, how long you would expect a satellite to last, and what the post failure plan would be?
-1 Uncomfortable Truth
Yes, the "rapid" advance of our technology... We don't even have the Concorde anymore.
We have plenty of supersonic aircraft, there just wasn't enough demand for the Concorde to justify its cost.
The thing with people like you is that you are just like a religious person. You don't want to hear reality.
What "reality" am I not "hearing"? You just present vague talk. The writer linked to earlier, presents arguments that just don't have much relevance to space activities.
But just in case, how much more time of nothing (in the sense of the grandiose stuff you propose, not cameras on wheels and radios in orbit) happening will convince you that nothing will ever happen?
I'd say about half a billion years probably would do. If life hasn't left Earth by the time the Sun goes nova, then that's a good indication that this stuff is impossible.
There will be no Moon colonies, no asteroid mining, no great shiny expansion of the glorious species into the empty vacuum of space, nothing.
And what is that based on? We've already demonstrated the physics and hence, reality allow it. We've seen steady progress on many technological fronts, such as cheaper manufacturing, cheaper orbital launch, and demonstration that we can maintain infrastructure and habitats in space indefinitely. People who say things are impossible have a really bad track record and I think this will end up being more of the same.
True enough.
I think you have O'Neill's reasoning backwards, though. He didn't say "we need to build solar power satellites, therefore we need a colony of 10,000 people"-- he said "we've shown that there are no showstoppers to building a colony of 10,000 people; what will they do? Here's an idea; they will build solar power satellites."
So, the question now is, if you don't need very many people-- and possibly don't need any people--in space to build solar power satellites, what is the economic base for off-Earth colonies?
http://www.geoffreylandis.com
To the AC above: If the majority of readers haven't heard about them either, then "who gives a fuck about L5?" Seriously, if this L5 society is worth at least even a little, they should be known as much as Space X, given that they've existed for so long.
The L5 society merged with the National Space Institute back in 1987 to form the National Space Society ("NSS") NSS is still around.
If you haven't heard of them, I'd say, well, so what? There are probably tens of millions of things you haven't heard of, some important, some not. That's a statement about you.
History of the L5 society here: http://www.nss.org/settlement/...
http://www.geoffreylandis.com
I've looked at various other orbits.
http://ntrs.nasa.gov/archive/n...
A problem with non-synchronous orbits is that 75% of the Earth's surface is ocean, and a vast amount of the remainder is uninhabited, so if a satellite isn't geostationary over the place you want, it will spend much of its time over places where you have no place to put a receiver or no market for power.
Nevertheless, I think that there may be clever solutions with other orbits; it could definitely use more thinking.
http://www.geoffreylandis.com
Exactly, that's the problem. There are/were some Christians who believe that conservationism (/"stewardship") was part of their responsibility, and while I disagree with the theology, I really like and appreciate the sentiment, and also agree that we have a responsibility to take of this place, for multiple reasons. Even the Muslims seem to have this viewpoint now, so it's really sad and pathetic that most Christians in America basically seem to think the Earth is theirs to fuck up however they want.
With some of the income and infrastructure from this project, why not use it as a way station for Mars expeditions? Build a self sufficient habitat and inject it into the favorable orbit between L5 and Mars. Then every two years a group of colonists could ride it with very little fuel expenditure to Mars. They would need to park their descent vehicle nearby. Food, water, and radiation protection could be provided in the habitat, with artificial gravity and greenhouse food production managed by a team of robots during the long sector of the orbit.
By focusing only on $ per kW or $ per other unit, you seem to be ruling out consideration of $ per mission or $ per step, thus requiring $billions to be spent up front on technology that has only been proven in the laboratory. This is roughly as difficult as trying to kickstart a fusion reactor using nothing more than a matchbook.
Have you given any thought to demonstration missions, or realistic paths to funding that might eventually unlock enough money for the full system as you describe it? ("Government funding" not being a realistic path, given their demonstrated history with regard to projects that might actually give cheap power to the masses. This applies to any government large enough to fund this - such as US, EU, Russia, or China - though the exact means by which each one has demonstrated it wouldn't fund this, except to sabotage it and thereby waste the energy of those who might otherwise build this for real, varies by government.)
If not, why not? That's as much a part of the problem that needs solving here as the technology, and you've shown you can solve the technical side.
The problem is that the republican party houses the lunatic fringe rather than cursing them like the dogs they truly are. As to whether it is from cult like off shoots of legitimate Christian churches or the loonie tune libertarians the republican party needs to oust these people. If you sleep with dogs you wake up with fleas or more directly if a candidate has a base filled with nut jobs then that candidate will have to keep those nut jobs happy to keep his position. That makes that candidate a dangerous person. So why do I say libertarians are nuts? They fir right in with the whacko church cults. They accepr of faith a notion that a public will be orderly without being governed. It has never, ever, been tried and there is zero evidence that anything other than slaughter or chaos would follow a libertarian take over whether by philosophy or force of arms. The same is true of the notion of capitalism or a free market society. No society of any kind has ever tried being capitalistic or operating a free market. So there is zero evidence that it could work. Some markets are a bit more free than others but no free market can exist and will never exist. So these types of nuts who speculate on the joys of untested notions belong right next to the drink the Cool Aide churches and libertarians. Strip away the loonie Christians, the libertarians and the capitalist Aynn Rand worshipers and how many republicans are left?