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Interviews: Ask Engineer and L5 Society Cofounder Keith Henson a Question

Posted by samzenpus on from the go-ahead-and-ask dept.

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.

111 comments

  1. Microwaving power to Earth from space by Anonymous Coward · · Score: 1

    If the beam becomes misaligned and strikes Iowa, how do you stop the entire state from exploding into a massive popcorn volcano?

    1. Re:Microwaving power to Earth from space by gcnaddict · · Score: 1

      Disable Disasters in the Disasters menu.

      --
      Viable Slashdot alternatives: https://pipedot.org/ and http://soylentnews.org/
    2. Re:Microwaving power to Earth from space by Grishnakh · · Score: 3, Informative

      I'm not Keith, but from what I've read about such systems, this isn't a concern: when they hit the Earth's surface, the microwave beam is very large so it wouldn't have a fatal effect on anyone or anything that happened to cross through it, though it might warm you up a bit. Also, the frequency is pretty important; microwave ovens work because they're tuned to the resonant frequency of water, which most of our food is largely composed of, so it excites the water molecules and makes them heat up. If the beam is tuned to something else, it might have very little effect on lifeforms crossing through it (which is probably the intention, since tuning it for water would make it attenuate too much on cloudy days).

    3. Re: Microwaving power to Earth from space by Anonymous Coward · · Score: 0

      There has been a long history of sailors 'cooked' in the radar's path. RF burns are deep and penetrating.

    4. Re: Microwaving power to Earth from space by Coren22 · · Score: 1

      Of course radar emits all frequency ranges, and therefore applies equally to all forms of RF emission...

      --
      APK likes to ask for responses to the same things over and over. Maybe he just likes the responses?
    5. Re:Microwaving power to Earth from space by Muad'Dave · · Score: 3, Informative

      ... microwave ovens work because they're tuned to the resonant frequency of water ...

      Bzzt. Microwave ovens use 2.4GHz because there's an ISM band there. There is no resonance at 2.4 GHz for water. If there was your food would explode in the oven.

      --
      Tiller's Rule: Never use a word in written form that you've only heard and never read. You will end up looking foolish.
    6. Re:Microwaving power to Earth from space by Mr+D+from+63 · · Score: 2

      Yes, very low energy per given area can ensure safety. But that means absolutely huge receivers are required to get a useful power level.

    7. Re: Microwaving power to Earth from space by rubycodez · · Score: 1

      no, there is documented higher incidence of testicular and eye tumors though

      the power per unit area is much HIGHER being near ship antenna than these proposed collection systems

    8. Re:Microwaving power to Earth from space by drinkypoo · · Score: 1

      Yes, very low energy per given area can ensure safety. But that means absolutely huge receivers are required to get a useful power level.

      To receive the kind of power levels we're talking about efficiently, you're going to need pretty damned big receivers. Luckily, they don't have to be large single physical structures - you'll have a rectenna array rather than one big one.

      --
      "You're right," Fisheye says. "I should have set it on 'whip' or 'chop.'"
    9. Re:Microwaving power to Earth from space by Mr+D+from+63 · · Score: 1

      A bunch of little ones all together, a smaller number of bigger ones, what does it matter? It still must cover a tremendous area.

    10. Re:Microwaving power to Earth from space by drinkypoo · · Score: 1

      A bunch of little ones all together, a smaller number of bigger ones, what does it matter? It still must cover a tremendous area.

      It does take up a lot of space, but you can put it someplace crappy that nobody goes anyway and it doesn't look like much of anything.

      --
      "You're right," Fisheye says. "I should have set it on 'whip' or 'chop.'"
    11. Re:Microwaving power to Earth from space by Mr+D+from+63 · · Score: 1

      Good luck with that.

    12. Re:Microwaving power to Earth from space by drinkypoo · · Score: 1

      Good luck with that.

      It works fine for every other kind of power plant, except they typically have to be sited on waterways, unlike a rectenna field. You're inventing objections which do not exist.

      --
      "You're right," Fisheye says. "I should have set it on 'whip' or 'chop.'"
    13. Re:Microwaving power to Earth from space by taiwanjohn · · Score: 1

      Or just forget about space-solar power altogether, as Elon Musk recommends.

      --
      XML is like violence. If it doesn't solve your problem, you're not using enough of it. --AC
    14. Re:Microwaving power to Earth from space by Mr+D+from+63 · · Score: 1

      Yes, it will all be wonderful.

      Oh, by the way, are you aware of the scale of area coverage we are talking about?

    15. Re:Microwaving power to Earth from space by Anonymous Coward · · Score: 0

      It's not a concern because such "systems", or rather, fantasies, make no sense whatsoever and have precisely zero chance of ever being built.

    16. Re:Microwaving power to Earth from space by Anonymous Coward · · Score: 0

      Boy is that a hard myth to dispel. I have no idea how it started but microwaves work on simple induced eddy currents in the "load", ie, your meal.

      Anyone who thinks a microwave oven is tuned is encouraged to show me the stabilized power supply and PLL lock to a stable reference... Guess what? The frequency output of a magnetron is all over the place, because it doesn't matter. It would work just as well at 3GHz too.

    17. Re:Microwaving power to Earth from space by DanielRavenNest · · Score: 1

      The fact that he helps run the U.S.'s largest ground solar installer isn't a conflict of interest?

    18. Re:Microwaving power to Earth from space by DanielRavenNest · · Score: 1

      So do solar panels. The difference is a rectenna array generates 300 W/m^2 for 24 hours a day, while solar panels generate about 200 W/m^2 from 4-6 hours a day in most decent locations. In crappy locations for solar (Seattle, Germany), the energy per land area is *way* higher for space beamed power.

    19. Re:Microwaving power to Earth from space by Mr+D+from+63 · · Score: 1

      ' a rectenna array generates 300 W/m^2 for 24 hours a day

      That is possible on the high end, but the topic of this thread was doing so with safe energy levels, and to be safe you need to be a lot closer to the 20 W/M^2 range. You can have a setup with higher levels in the center and lower at the edges of the beam, but when beaming from such a great distance it is difficult to manage such an intensity distribution.

      For even 80 W/M^2 average, it would take a receiver surface area of about 3 square miles to produce 600 MW ( the size of a medium fossil plant, just for reference).

    20. Re:Microwaving power to Earth from space by Grishnakh · · Score: 1

      Why do you need 20W/m^2 for safety? The sun beams 200W/m^2 on sunny days and the worst damage it does is sunburn and deterioration of plastics.

    21. Re:Microwaving power to Earth from space by Mr+D+from+63 · · Score: 1

      UV radiation is the component of sunlight that burns, it is only a slice of the spectrum. That part of the spectrum is not 200 W/m2.

      Microwaves interact differently with the human body than UV radiation, so the comparison would not necessarily be telling. My quick searches showed safe levels need to be in the range I specified, I'll admit I don't know the science behind them.

    22. Re:Microwaving power to Earth from space by DanielRavenNest · · Score: 1

      Standing inside the fence of a rectenna array makes as much sense as going inside the furnace of a coal power plant. In other words, no sense at all.

      300W/m^2 is the average intensity on the receiving antenna elements. The intensity outside the fence is much much lower. There's a buffer zone between the edge of the antenna and the fence.

    23. Re:Microwaving power to Earth from space by Mr+D+from+63 · · Score: 1

      Standing inside the fence of a rectenna array makes as much sense as going inside the furnace of a coal power plant. In other words, no sense at all.

      300W/m^2 is the average intensity on the receiving antenna elements. The intensity outside the fence is much much lower. There's a buffer zone between the edge of the antenna and the fence.

      That is not the configuration that most articles describe, where the antenna covers the full range down to safe levels. And it makes no sense because if you don't you are wasting a lot of energy falling on what is now a unusable zone outside the receiver, not to mention still taking up all that area which was part of the original point.

      These space to earth systems are still a paper exercise. To state that "300W/m^2 is the average intensity on the receiving antenna elements." is not based on anything proven nor shown to be practical when controlling a beam over such a huge distance but still keeping the spread at a minimum. It may be possible. IF so, there is still a list of issues that comes to play when moving to higher energy levels, including significant EMI/RFI impacts. There is consideration of birds and insect flying overhead. etc.

    24. Re:Microwaving power to Earth from space by Anonymous Coward · · Score: 0

      Musk is not an expert on space-based solar power. He ignores the fact that a space-based collector not only gets sunlight at far greater intensity, it wouldn't be occluded half of the time the way a ground collector is.

    25. Re:Microwaving power to Earth from space by Anonymous Coward · · Score: 0

      36% more intensity and 400% more hours of sunlight at only 14,000x more money.

    26. Re:Microwaving power to Earth from space by Geoffrey.landis · · Score: 1

      ' a rectenna array generates 300 W/m^2 for 24 hours a day

      That is possible on the high end, but

      Not even possible on the high end. The diffraction-limited beam spread means that you can't focus the beam to a tight spot, without making the space transmitter correspondingly larger. The Glaser sizing of a kilometer-scale transmitter in space beaming to a ten-kilometer scale spot on the ground wasn't picked at random; those are the sizes you need. And the keep-out zone around the ground receiver is much larger; due to the diffraction wings.

      Shorter wavelengths make things better... but if you go too short, your beam gets absorbed by water molecules, and clouds start blocking the beam.

      (of course, you can still use the keep-out zone for lots of uses; farming, for example. You just don't want to put houses and playgrounds there.)

      --
      http://www.geoffreylandis.com
    27. Re:Microwaving power to Earth from space by losfromla · · Score: 1

      Oklahoma?

      --
      Only I can judge you.
  2. Big coal also wanted him dead by Anonymous Coward · · Score: -1, Flamebait

    They want him to die. The Republicans hate the Earth so they constantly dig-up dirty coal to burn it to pollute this planet. They hate us and all over life which is why they want to stop him. Stop him. They hate us all. No one should ever vote for them.

    1. Re:Big coal also wanted him dead by Grishnakh · · Score: 0, Flamebait

      Don't be ridiculous; Republicans don't "hate the Earth" or "hate us all".

      Basically, there's two kinds of Republicans: religious kooks (like Santorum or Huckabee) and libertarians/ultra-capitalists. Some are a bit of a mixture of the two, but usually they're in one or the other camp, though even the libertarian ones will pander to the religious kooks to get votes (like Rand Paul).

      The libertarian ones are basically sociopathic (along with their buddies in polluting industries), and simply don't care about the Earth or pollution. They want money, the more the better, and they don't want anything standing in their way. It's not that they hate the Earth, they simple don't give a shit. The effects aren't going to be that bad before they're dead, so why would they care?

      The religious kooks don't hate the Earth at all, they just have an insane belief that humans can't possibly do anything to cause real harm to "God's creation", and that God will prevent anything bad from happening to them as long as they're faithful. So maybe some of them are worried about climate change and such, but instead of blaming themselves and their stupid, gas-guzzling SUVs and 2-cycle lawn equipment, they blame gay people.

      At least the liberatarian/capitalist ones are rational, even if it is entirely selfish.

    2. Re:Big coal also wanted him dead by rubycodez · · Score: 1

      because none of the top coal mining states are Democrat, like say West Virginia or Kentucky? You're an idiot

    3. Re: Big coal also wanted him dead by Anonymous Coward · · Score: -1

      Please do not confuse libertarianism with objectivism. Ayn Band hated libertarianism because it emphasizes protecting individual rights, while her philosophy centers on the rights of organizations. Some republicans lean libertarian, but the ones who spout Rand quotes do not. You'll find far more libertarians in the Democratic camp.

    4. Re:Big coal also wanted him dead by Spy+Handler · · Score: 2

      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".

    5. Re:Big coal also wanted him dead by drinkypoo · · Score: 1

      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.'"
    6. Re:Big coal also wanted him dead by tomhath · · Score: 1

      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.

    7. Re: Big coal also wanted him dead by Grishnakh · · Score: 1

      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.

    8. Re:Big coal also wanted him dead by Grishnakh · · Score: 1

      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.

    9. Re:Big coal also wanted him dead by Grishnakh · · Score: 1

      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....

    10. Re:Big coal also wanted him dead by tomhath · · Score: 1

      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

    11. Re:Big coal also wanted him dead by Anonymous Coward · · Score: 0

      The religious kooks don't hate the Earth at all, they just have an insane belief that humans can't possibly do anything to cause real harm to "God's creation", and that God will prevent anything bad from happening to them as long as they're faithful. So maybe some of them are worried about climate change and such, but instead of blaming themselves and their stupid, gas-guzzling SUVs and 2-cycle lawn equipment, they blame gay people.

      Allow me to recharacterize the religious kook position: they believe humanity has a mandate for "stewardship" of the earth.

      Interpretations of this stewardship mandate encompass a broad spectrum from (speaking as God) "Take care of it until I get back" to "Use it while you can. I'm already working on 2.0"

      In my experience as a kook with the former view, the median interpretation is closer to the latter.

    12. Re:Big coal also wanted him dead by Grishnakh · · Score: 2

      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.

    13. Re:Big coal also wanted him dead by JimSadler · · Score: 1

      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?

  3. Watch out for Krieger waves by Anonymous Coward · · Score: 0

    and your wife around Riker.

  4. Go away greenwow by Anonymous Coward · · Score: -1

    You are an idiot.

  5. Missile technology by Anonymous Coward · · Score: 0

    Hey Keith, do you think a Tom Cruise Missile would have the required lift to escape Earth's gravity, or would the giant ego of some Hollywood types get in the way?

  6. Valerie by Anonymous Coward · · Score: -1

    Is it too soon to ask?

  7. Re:Watch out for Krieger by U2xhc2hkb3QgU3Vja3M · · Score: 0

    Jazz Hands!

  8. L5? by U2xhc2hkb3QgU3Vja3M · · Score: 1

    He co-founded the L5 society in 1975, which sought to promote space colonization.

    I was born three years earlier than this project and that's the first time I ever hear about it.

    1. Re:L5? by Anonymous Coward · · Score: -1

      Who gives a fuck if you've heard of it or not?

    2. Re:L5? by U2xhc2hkb3QgU3Vja3M · · Score: 1

      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.

    3. Re:L5? by ShanghaiBill · · Score: 3, Informative

      I was born three years earlier than this project and that's the first time I ever hear about it.

      The L5 Society is well known among space colonization kooks (SCKs). As a SCK, I first learned about the L5 Society in the 1980s. They do good work, advocating practical projects. Putting O'Neill Cylinders at the Lagrangian points is a much more sensible goal than trying to put a human colony on Mars.

    4. Re:L5? by gstoddart · · Score: 1

      Well, in fairness ... are you claiming to be the majority of readers on Slashdot? Because that would be pretty bold of you.

      Certainly other people have heard of them. I've heard of them. At least one other poster seems to have heard of them. Google has heard of them. So one guy says he's never heard of them and they don't exist? How do I get that job?

      To reiterate the rather crude point of the AC ... we don't care what you had for lunch either. That you don't know who they are is, as a metric of their utility or influence, almost meaningless.

      They exist independent of if you know of them or not.

      --
      Lost at C:>. Found at C.
    5. Re:L5? by thinkwaitfast · · Score: 3, Informative
      I went to an L5 meeting when I was in high school. I was a big science geek, space nerd and Joseph Lagrange (the L in L5 - I'd taught myself how to calculate a few years before hearing of L5 society) was my hero. I took the bus across two towns to attend this meeting with a guest speaker from Caltech.

      It was a major letdown in my young life. Instead of talking about things like orbital mechanics and how to make the economics work, the meeting consisted of kooks and was centered around making fun of people who didn't know the space shuttle couldn't land on the moon and a short speech from a woman who was writing a sci-fi book about sex in space. The best term that I've heard about those people is space nutters. I went because I wanted to learn and do something, but only learned that space is a cargo cult to many.

    6. Re:L5? by taiwanjohn · · Score: 1

      Why not L1 or L2? They both have a lower delta-v budget than L5. Is there some particular advantage to L5 that makes it a better choice?

      --
      XML is like violence. If it doesn't solve your problem, you're not using enough of it. --AC
    7. Re: L5? by Anonymous Coward · · Score: 0

      L4 and L5 are stable orbits. L1-3 are unstable, and it's easy to disturb the orbit of something parked there.

    8. Re:L5? by U2xhc2hkb3QgU3Vja3M · · Score: 1

      I said if the majority of readers haven't heard about them either...

      Slashdot is running so many (paid) stories on nobodies these days, the real stories get buried under a metric ton of crap.

    9. Re:L5? by ShanghaiBill · · Score: 3, Informative

      Why not L1 or L2?

      L1 and L2 are not stable. A slight perturbation can push you out of orbit, and energy must be continuously expended to stay in position. L4 and L5 are stable. After a slight perturbation, a space station would settle back into the original orbit.

      They both have a lower delta-v budget than L5.

      Sure, but a bit extra delta-v is no big deal once you are "in space". The hard part is getting out of the atmosphere and into orbit. You need expensive chemical rockets for that. But once in orbit, you can take your time, and use cheap ion thrusters to move to your final position.

    10. Re:L5? by Anonymous Coward · · Score: 0

      It's because all it is is a mailing list for Space Nutters to share prayers and religious fervor with fellow congregationists.

  9. Creative ideas by Anonymous Coward · · Score: -1

    Where did you first get the idea for the Muppets?

  10. Any relation to Chris Hansen? by Anonymous Coward · · Score: -1

    it would be so fucking ironic if he was arrested for underage sex with ... the entire boy band Hanson!

  11. Asteroid Mining by meta-monkey · · Score: 4, Interesting

    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.
    1. Re:Asteroid Mining by Grishnakh · · Score: 1

      From what I read, we recently just missed an asteroid that was estimated to have a quadrillion dollars' worth of platinum in it.

    2. Re:Asteroid Mining by meta-monkey · · Score: 1

      Sure, but when you're talking about quantities like that, it crashes the market. Who can buy a quadrillion dollars' worth of anything?

      That's not a reason not to do it, of course. But as far as capitalism goes it's kind of a catch-22. It's expensive because it's rare, but spend $100 billion getting an asteroid full of it and it's now so common as to be worthless. So in my question I wanted to avoid those kinds of questions. I'm just curious about the machines.

      --
      We don't have a state-run media we have a media-run state.
    3. Re:Asteroid Mining by gstoddart · · Score: 1

      Sure, but when you're talking about quantities like that, it crashes the market. Who can buy a quadrillion dollars' worth of anything?

      Shhh ... don't say that ... or the copyright cartels will have to explain how they've lost more to piracy than the next 100 years of the economic output of planet Earth. Stock valuations will have to be reconsidered. Executive bonuses recalculated.

      There are business models which rely heavily on made up projections of value.

      Business models!! Don't go messing with business models.

      You go around saying they're completely absurd and made up and they'll lock you up or something.

      --
      Lost at C:>. Found at C.
    4. Re:Asteroid Mining by Grishnakh · · Score: 1

      Well yes, obviously if some company captured that asteroid and dumped that much platinum on the world market at dirt-cheap prices, the price would crash (to whatever price they sold it at). But they'd probably limit the supply of the material (since they have so much of it relative to anyone else) to keep the price from crashing too much, plus they'd still make tons of money selling it. And don't forget, their acquisition costs would be huge (no one's captured an asteroid before), so they're not going to sell the stuff for peanuts, they still have to recoup their cost.

      Also, if the price of platinum fell greatly (so it was as expensive as, say, titanium, which is costly compared to steel but not compared to platinum), that would probably open up all kinds of new markets for it, and the demand would increase greatly to compensate. There's a lot of industrial uses for platinum, and making it cheaper would make people find more places to use it.

    5. Re:Asteroid Mining by meta-monkey · · Score: 1

      Thanks for having my back. Almost got myself in trouble in there.

      The Emperor's clothes are beautiful, the Emperor's clothes are beautiful, the Emperor's clothes...

      --
      We don't have a state-run media we have a media-run state.
    6. Re:Asteroid Mining by DanielRavenNest · · Score: 3, Informative

      I've been working on a textbook about Space Systems Engineering: http://en.wikibooks.org/wiki/S...

      In section 4.9 I do the numbers for orbital mining: https://en.wikibooks.org/wiki/...

      The first product of asteroid mining is likely to be rocket fuel. Some asteroids (the carbonaceous type) contain up to 20% water and carbon compounds. This can be processed to Oxygen + Hydrocarbons, which is a common high-thrust rocket fuel. The lifetime mass return ratio of an asteroid tug is ~350:1, and if 20% is usable fuel, then you gain 70:1 just on that one product. Extracting water and carbon compounds only requires kitchen oven level heat, which is easy to do by concentrating sunlight.

      There are lots of other products we can potentially extract from asteroids, but that's the easiest and most useful, since most anything you do in space needs some fuel to get where you want to go.

      Asteroids did have geological processes, just different ones. The "metallic" type come from protoplanets which melted internally from radioactive decay early in their history. The iron and iron-loving elements sank to the core because they are the densest. Later collisions broke up the protoplanets, exposing their cores. The metallics are a high percentage of iron, nickel, cobalt, and a few other elements. The "stony-irons" come from regions that didn't fully separate the core and rocky layers. They range from low to high percentage iron, with the remainder being rock.

      The other process that happened is thermal. Depending how far from the Sun a given asteroid first formed, and later orbit history, certain compounds condensed or not, and then could be baked. Probably the most significant difference is due to the "frost line", the distance at which water ice can remain solid in a vacuum. It happens to be right in the middle of the Asteroid Belt, where Ceres is. Objects beyond that distance tend to have a lot of water. Anything closer tends to have little water, though it can contain "hydrated minerals", where the water is chemically bound.

      We actually know quite a bit about the composition of asteroids. Nature delivers samples to Earth in the form of meteorites. We can compare the spectra of meteorites to those from asteroids we get through telescopes, and infer what they are made of. We have flown past or orbited several asteroids, most notably the Dawn mission to Vesta and now Ceres, two of the largest asteroids. Spacecraft carry a larger variety of instruments and can do a better job of telling what the asteroids are made of.

      As far as materials processing, we can design machines based on meteorite samples, or simulated samples, since meteorites are rare and valuable. If the Asteroid Redirect Mission that NASA wants to do happens, we would have a sizable boulder to experiment with. After taking science samples, they could try various processing methods on an actual piece of asteroid rock, in zero-g. I don't think we can design serious production units without a a few rounds of trying it on a small scale. For that, we would need at least a small asteroid tug that fetches back chunks from different asteroid types, so we have enough raw materials to experiment on. Most known asteroids are too big to move whole. A 30 meter one is anywhere from 18,000 to 90,000 tons. So for early space mining, we are talking about scraping loose stuff off their surfaces, or grabbing boulders.

      my email is the same as my user name here, but lowercase, and add (at)gmail. Feel free to contact me if you want more information. I can point you at sources I have, or send you stuff directly.

    7. Re:Asteroid Mining by meta-monkey · · Score: 1

      Thank you for the information and all your hard work! I'll check out your book.

      --
      We don't have a state-run media we have a media-run state.
  12. Cost per KWh by Rob+Lister · · Score: 2

    What is the cost per KW for the build/deployment and resultant cost per KWh for the end user?

    1. Re:Cost per KWh by Mr+D+from+63 · · Score: 1

      What is the cost per KW for the build/deployment and resultant cost per KWh for the end user?

      Ha hah ha! Cost he says.. Hah! What a funny guy! The answer is of course, "cheaply". After all, its the future.

    2. Re:Cost per KWh by gstoddart · · Score: 1

      Maybe he's one of those wacky future looking people who is interested in getting scarce resources less scarce, and less in the hands of corporations worried about the cost per KWh for the consumer?

      In which case it's not so much of a business plan, as a future direction for humans to solve our energy problems because the sun makes more than we could ever need.

      And then the MBAs and CEOs will come in and fuck it up and try to figure out how maximize return on investment and shareholder value.

      --
      Lost at C:>. Found at C.
    3. Re:Cost per KWh by DanielRavenNest · · Score: 1

      Competitive with ground power, or it would never be built in the first place.

      In space you get ~7 times as much sunlight as the average place on Earth. That's due to absorption, night, and weather that happens down here, but not in space. The logic is then you can spend up to 7 times as much building your space solar power system and be competitive with Earth solar power. If it costs you more than that, just build ground solar.

    4. Re:Cost per KWh by Anonymous Coward · · Score: 0

      The paper gives a cost of 3 cents per kilowatt hour.

    5. Re:Cost per KWh by Rob+Lister · · Score: 1

      Hopefully his answer will be a little more specific than simply 'competitive'. I'm not looking for an exact number but, given the technology at hand, a somewhat narrow range would be nice.

    6. Re:Cost per KWh by Geoffrey.landis · · Score: 1

      Competitive with ground power, or it would never be built in the first place. n space you get ~7 times as much sunlight as the average place on Earth.

      Well, but of course you don't put solar arrays on the average places on Earth, you put them in the best places. With a tracking array, that number gets to be much closer to a factor to two than a factor of 7. So the take-away lesson is that you don't build space power systems for terrestrial use until after the market for power from the best solar sites has already been saturated. This means that the market for space solar power substitutes for storage and power transmission technologies.

      That's due to absorption, night, and weather that happens down here, but not in space. The logic is then you can spend up to 7 times as much building your space solar power system and be competitive with Earth solar power.

      Only if the transmission efficiency were 100%, and it's not.

      If it costs you more than that, just build ground solar.

      --
      http://www.geoffreylandis.com
  13. microwaves?! are you stupid?! by Anonymous Coward · · Score: 0

    Since you're already going to be up in orbit, why not generate antimatter so we can build some big-boy interstellar rockets?!!
    I'm sure it's just a simple matter of engineering to ship that to use in Earthbound reactors if you are so inclined.

  14. As I understand this by Ungrounded+Lightning · · Score: 3, Informative

    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
  15. Do transgender women pee standing up? by Anonymous Coward · · Score: -1

    Serious question...

  16. Space Elevator by Btrot69 · · Score: 2

    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 ?

    1. Re: Space Elevator by Anonymous Coward · · Score: -1

      Is it because the the Skylon rocket has a cool name and resembles a giant penis ?

    2. Re:Space Elevator by DanielRavenNest · · Score: 1

      I recently did a class on space elevator design:

      - Class notes: https://en.wikibooks.org/wiki/...

      - Slides: http://imgur.com/a/cCTY5

      The "classical" space elevator (ground to GEO) can't be built, even with carbon nanotube cable. There are more modern versions that can be built. Realistic engineering designs have to consider a lot of factors that artist's illustrations you most likely have seen don't.

    3. Re: Space Elevator by Anonymous Coward · · Score: 0

      It's because Skylon offers a drastic reduction in lift cost without the need to invent new materials as the space elevator would require.

    4. Re: Space Elevator by Anonymous Coward · · Score: 0

      Carbon nanotubes already exist, we just have to make them longer.: this from 2013:
      "Chinese scientists at Tsinghua University in Beijing have managed to grow a carbon nanotube (CNT) that is just over half a metre long â" over double their previous bes." http://www.rsc.org/chemistryworld/2013/07/carbon-nanotube-record-half-metre-long

      The space race between the US and the Russians WAS little more than a competion of giant phalluses.

      US engineers needs to stop obsessing on the size of their rockets.

  17. How is L5 a possibility? by Thing+1 · · Score: 1

    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.
  18. Why no Bernal Sphere's? by jacksdl · · Score: 1

    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.

  19. This man induces wonderful journeys through wikipe by HeckRuler · · Score: 2

    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.

  20. And when you're done, some reality by Anonymous Coward · · Score: 0

    When you're done with your sci-fi high and fantasies, get back down to Earth...

    http://physics.ucsd.edu/do-the-math/2011/10/why-not-space/

    1. Re:And when you're done, some reality by khallow · · Score: 1

      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.

    2. Re:And when you're done, some reality by Anonymous Coward · · Score: 0

      "Bizarre assumptions" is Space Nutter code for physics, reality, and limits.

      Nothing will happen in space. Ever.

    3. Re:And when you're done, some reality by khallow · · Score: 1

      "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.

    4. Re:And when you're done, some reality by Anonymous Coward · · Score: 0

      Yes, the "rapid" advance of our technology... We don't even have the Concorde anymore.

      The thing with people like you is that you are just like a religious person. You don't want to hear reality.

      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?

      There will be no Moon colonies, no asteroid mining, no great shiny expansion of the glorious species into the empty vacuum of space, nothing.

      Ever.

    5. Re:And when you're done, some reality by khallow · · Score: 1

      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.

  21. Child Molester ? by Anonymous Coward · · Score: -1

    I found this when I googled Keith Henson http://valerieaurora.org/keith...

  22. So, whatever happened, anyway? by Anonymous Coward · · Score: 1

    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.

    1. Re:So, whatever happened, anyway? by Anonymous Coward · · Score: 0

      The criminal nut-cult still exists, but its not as big or rich as it once was. Keith had a lot to do with that, but the biggest blow was Tom Cruise showing the world what a fucking loon he is.

    2. Re:So, whatever happened, anyway? by Anonymous Coward · · Score: 0

      Keith Henson is a pedophile, he just cleverly brought in the whole Scientology angle to deflect attention.

    3. Re:So, whatever happened, anyway? by Anonymous Coward · · Score: 0

      Oh, look: It's a scientology minion dropping by to smear Keith again.

      Fuck you, and fuck the batshit crazy dwarf you work for, you clambot piece of shit.

  23. We've learned a lot by Geoffrey.landis · · Score: 1

    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
    1. Re:We've learned a lot by DanielRavenNest · · Score: 2

      Hi Geoff. Dani Eder here. I would say the most important thing we have learned is "there are a whole lot of Near Earth Asteroids". In 1980 there were 52 known NEA's ( http://neo.jpl.nasa.gov/stats/ ). Today we are rapidly approaching 13,000 at a rate of about 1,500 new ones a year. This has completely changed the accessibility of raw materials. Given that we now have well developed electric propulsion, 90% of NEA's take less fuel to reach than the surface of the Moon.

      Even if you want to go to the Moon, the math says to mine asteroids for propellant to get there. Some asteroids are up to 20% water and carbon. This can be reformed to Oxygen and Hydrocarbons, which makes good high-thrust chemical propellant for landers.

      Next I would say the advances in computers, automation, robotics, and high bandwidth communication are important. O'Neill assumed 10,000 people in a colony, because that's how many people it would take to build solar power satellites and all of the supporting tasks to keep them alive. Today we can think about automating it or controlling a lot of that from the ground. That means we can bootstrap construction with a small team of actual humans in space (some tasks still have to be hands-on).

      Lastly, I would mention that the "O'Neill Cylinder" design, while pretty, is a nightmare from an engineering safety standpoint. One meteorite or out of control cargo ship hitting those giant windows, and all your air leaks out. You want stuff like multi-layered Whipple shields to break up incoming objects, and a layered and compartmentalized pressure hull. If you want natural sunlight, bring it in through protected openings.

    2. Re:We've learned a lot by Anonymous Coward · · Score: 0

      Normal people have learned that it will never happen. Nerds like you and the Space Nutters, the religious branch of the space true believers, will keep yelling at each other about "this rock" and the "death asteroid" and "the species". See post below.

  24. Freezing people by Anonymous Coward · · Score: 1

    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?

  25. Oh my... by tomhath · · Score: 1

    If that's true he has some explaining to do.

  26. Why geosynchronous orbit? by Anonymous Coward · · Score: 0

    Has anyone considered using a semi synchronous orbit with multiple receivers around the world to provide electricity to places at peak times (4pm to 8pm) when electricity is more expensive? I'm curious about the economics of it all.. e.g. how much down time would such a system have (as it's over the pacific say), what's the price of a receiving station, what's the comparative peak vs base load price of electricity? Would the sun still be visible to a satellite in semi synchronous orbit that can beam to a place on earth at 8pm (I imagine so) etc.

    1. Re:Why geosynchronous orbit? by Geoffrey.landis · · Score: 1

      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
  27. What "wear and tear" factors are relevant. by ShieldW0lf · · Score: 1

    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
  28. What do we do, if there's nothing to do? by Geoffrey.landis · · Score: 1

    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
  29. L5 is now the NSS [Re:L5?] by Geoffrey.landis · · Score: 1

    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
  30. Power beaming was hashed over at The Oil Drum by Anonymous Coward · · Score: 0

    and shown to be a pointless make-work project.

    http://www.theoildrum.com/node...
    http://www.theoildrum.com/node...
    http://www.theoildrum.com/node...

  31. Re:L5 Society by Anonymous Coward · · Score: 0

    I never knew the reason they were considered kooks, but my dad (G.K. O'Neill) did indeed dislike the L5 society, for what it's worth (probably nothing, to \.ers). Wasn't crazy about the Planetary Society either, not surprisingly. "Is the surface of a planet really the right place for an expanding technological civilization?" Obviously his answer was 'no.'

    I really hope to see space-based solar power become useful, if the technology pans out. It was a big part of his dreams for colonization, and we need a better energy 'ecosystem' to improve our future, and to help us get some of our eggs out of this vulnerable single basket.

    signed: daughter #2

  32. Transportation station by Jack+Dixon · · Score: 1

    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.

  33. Minimum cost by Winged+Cat · · Score: 1

    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.