“If nothing comes of the challenge, yes, it’s a nuisance and a waste of time for everyone concerned.”
Max_OK, interesting, so how do you measure whether ‘nothing comes out of it’? How are you deciding that?
Comment on 2014 → 2015 by John Carpenter
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Comment on 2014 → 2015 by Rob Ellison
So Maxy is a drop out. Peace and love man.
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Comment on 2014 → 2015 by Rob Ellison
Yes it comes from the JISAO site as I said – with some annotations.
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Comment on 2014 → 2015 by AK
@Bob Ludwick...<blockquote>Given the expected efficiencies of all subsystems of the on orbit collection system/ground collection system/ and a postulated requirement of delivering 1 gigawatt to the grid, does anyone have a plan for collecting the required number of gigawatts of solar energy on orbit, turning it into the number of gigawatts required to energize the downlink laser, building a laser with a 10 meter aperture that will produce the required downlink power, and keeping the whole shebang pointed at the ground station with a total pointing error of less than a tenth of an arc second under all conditions of sun loading, station keeping thrusters, etc? </blockquote>In this design, based on the one proposed in the papers linked above, the laser is a tiny, mm-scale, crystal pumped with reflected sunlight. A non-paywalled discussion from 2011 is <a href="http://www.opticsinfobase.org/oe/fulltext.cfm?uri=oe-19-27-26399&id=225792" rel="nofollow">here.</a> They used a Fresnel lens, obviously not appropriate for space, but very thin mirrors can probably work.
I don't know where you got the <i>"10 meter aperture"</i>, no such thing is necessary. I assumed a 3-meter focusing mirror, along with a much smaller convex mirror, to focus the output of a tiny laser. To intercept a 100-meter ground installation, at 40,000,000 meters, the effective size of the source as seen by the main focusing mirror would have to be 1/400,000 the distance. At 10 meters that's 20 μ-meters. Note that this small size is produced by the convex mirror, it's not the size of the actual laser.
The aiming thing is <a href="http://www.opticsinfobase.org/oe/fulltext.cfm?uri=oe-18-13-13451&id=201843" rel="nofollow">in work</a>, although it's not completely there yet for geosynchronous heights.<blockquote>And could you keep the 100 meter collector at the tip of the 2000 meter pyramid from moving more than a meter or so under all conditions of wind/sun loading?</blockquote>Yes, considering it's guyed all the way to the top.<blockquote>At the ground station, how much energy would have to arrive at the surface of the 100 meter collector to deliver 1 gigawatt to the grid, after allowing for the conversion efficiencies of all the subsystems between collection surface and grid input? I suspect that 20% would be optimistic, but I would be happy to be wrong. </blockquote>Be happy then. As I mentioned above, the efficiency would be around 50% (48.67%) between the intensity of the laser (leaving the main focusing lens) and the terminals of the ground-side PV. This allows for atmospheric absorption (virtually nil), energy loss between the 1.2398 eV photon energy of the 1 μ-meter light from the laser and the 1.11 V band gap of silicon, the ~0.4 volt drop to a typical open-circuit voltage, and the ~85% efficiency for actual operation. (Using 87% the figure is 49.81%.)
I don't have all this stuff at my fingertips ready to post, but I gathered the appropriate links and have spent the time dragging the numbers out of them on the off chance that you're sincere in your interest. I was surprised at the efficiencies available, although I've seen higher numbers floating around.<blockquote>Just as an aside, if the anticipated MTBF of the on orbit system is not infinite, how is maintenance handled?</blockquote>Probably the same way re-supply for station-keeping reaction mass is: small satellites with bigger reaction motors, that drift around doing the necessary. Like resupply, when you're talking about 200,000 satellites, it's a regular function, not some sort of emergency.<blockquote> I. e., will ANY of them supply more energy to the grid than is required to install and operate them?</blockquote>Well, pushing a 10-kilogram powersat to escape velocity (<12Km/s) will require well under 1 gigajoule. Assuming it delivers even 1 KWatt to the grid (2 KWatt of laser, 2% of the >100 KWatt of sunlight intercepting its 100-meter collector), each powersat will return that gigawatt in about 1,000,000 seconds: under 2 weeks. One of the articles I linked referenced <b>30Watts/square meter</b>, so we're well within lab-demonstrated limits.
Studies of rail/coilguns for pushing such objects to high speeds have shown it to be easy and (relatively) cheap. The big problem is providing a tube of vacuum between the muzzle of the vertical railgun and space. I'm working on some calculations for that, using relatively cheap, high-strength materials.
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Comment on 2014 → 2015 by ordvic
Josh, sorry several of my comments went missing (prolly from my end). I’ll try to respost. Your charts showed a confirmation of polarization. The question is not whether the repbs moved right more than dems, it was if the dems moved left. The Pew chart shows 94% leftward move by dems and 92% right move of repbs ala polarization. The only two movements away from polarization is immigration and gay rights that I think you’d agree with me is a good thing. The context of the questions as you assert is prolly right more rightward movement. However, in my opinion the country has moved gradually left my entire lifetime. Even Goldwater championed gay rights in his last years and said he was decieved by the chief justice regarding his civil rights vote. He was told it was unconstitutional and later regretted the vote. So in my opinion the right is actually less right than what I remember in my youth, it’s just that the country has moved left and it makes any right move shift look exaggerated.
As to ‘rejuvenated’ you are prolly right. After Jimma Carter the repubs moved right and Reagan was a unique politition that offered hope. I think that ultimately led to repb majorities in congress not seen since the late forties early fifties. George W also ruined the Republican brand and Obama offerred ‘hope’ (stole that from Bill Clinton, don’t know how he got away with it. So he did rejuvenate but it wanned as you said. We’ll have to see if he is looked at more fondly in the future (sorta like Harry Truman) and it helps the dem view of things. After the Reagan revolution it’s been just a bunch of Reagan wanna bes including W, I think Romney was the only outliar there.
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Comment on 2014 → 2015 by AK
@Bob Ludwick…
Response in moderation. Not sure why, it had only 2 links.
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Comment on 2014 → 2015 by John Smith (it's my real name)
Tonyb
HNY
butting in here in regards to your concerns up thread about our American leadership selection process
it occurs to me that we are developing royal bloodlines in US
a Clinton/ Bush race is quite possible
that unfortunate spat in the late 1700s may have been for naught
perhaps it is the natural order of things
any advice for your wayward brethren?
that Duke, Earl, and Lord stuff gets a bit confusing
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Comment on 2014 → 2015 by Rob Ellison
‘Climate in the North Pacific and North American sectors has experienced interdecadal shifts during the 20th century. A network of recently developed tree-ring chronologies for Southern and Baja California extends the instrumental record, and reveals decadal-scale variability back to AD 1661. The Pacific Decadal Oscillation (PDO) is closely matched by the dominant mode of tree-ring variability, which provides a preliminary view of multi-annual climate fluctuations spanning the past four centuries. The reconstructed PDO index features a prominent bidecadal oscillation, whose amplitude weakened in the late 1700s to mid-1800s. A comparison with proxy records of ENSO suggests that the greatest decadal-scale oscillations in Pacific climate between 1706 and 1977 occurred around 1750, 1905, and 1947.’ https://www.ncdc.noaa.gov/paleo/pubs/biondi2001/biondi2001.html
Data is available there – knock yourself out.
NASA put the shift to cold conditions at 2008..
‘A cool-water anomaly known as La Niña occupied the tropical Pacific Ocean throughout 2007 and early 2008. In April 2008, scientists at NASA’s Jet Propulsion Laboratory announced that while the La Niña was weakening, the Pacific Decadal Oscillation—a larger-scale, slower-cycling ocean pattern—had shifted to its cool phase.’ http://earthobservatory.nasa.gov/IOTD/view.php?id=8703
I’d put the shift at 2002 from biological and other considerations.
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Comment on 2014 → 2015 by ordvic
Josh, I made 3 posts that didn’t make it (prolly from my end). I’ve given up. Your points are well taken though.
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Comment on 2014 → 2015 by Max_OK, Citizen Scientist
My God, you are as clueless as Allison. He’s trying to convince us that exposure to radiation is safe and cites a statement by Curie who later dies from exposure to radiation.
It would be different if Curie had recommended everyone die, because getting older is a drag, and exposure to radiation is the best way to die.
I didn’t know her husband was run over by a bus.
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Comment on 2014 → 2015 by PMHinSC
R. Gates | December 31, 2014 at 4:39 pm |
“When I do make the occasional post in 2015, I will make sure it is something of substance and worthy content.”
Perhaps others will also make a similar resolution. The 350 odd comments on this post alone have 30,000 words (including header and etc.), which makes for a formidable challenge separating the words from the thoughts; or even finding the thoughts for that matter. Can’t help but wonder if some are using bantering and blathering as the equivalent of a “denial-of-service” attack.
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Comment on 2014 → 2015 by David in TX
The answer to clouds is redundancy. Large distribution grids on the ground with a great many antennas. The laser in orbit can be steered quickly and easily such that it can steer itself as needed to a cloud free antenna. Power users draw from a grid not individual entry points.
No real reason to do that however. Mining and manufacturing technology will become more and more automated dropping the cost finished goods so much that the prohibitive costs of stuff today, like solar power panels and continent spanning power grids, become inconsequential.
Trying to plot solutions to problems anticipated 100 years from now where those solutions are crafted with methods and materials we have today is uber-stupid. We might all be living in the matrix in 100 years and not need more than a few microamps per virtual person. Virtual reality gets better and cheaper every day. At some point it must become better and cheaper than the real world.
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Comment on 2014 → 2015 by Max_OK, Citizen Scientist
jim2 wants to pollute and pass the costs on to future generations. Why not, what have future generations done for him?
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Comment on 2014 → 2015 by David Wojick
So our civilization is still based on fire. Food too. Fundamentals are hard to change.
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Comment on 2014 → 2015 by David Wojick
The luxury is rather appalling, but a major hydro program takes a few more zeroes on the numbers. Perhaps they cannot afford it.
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Comment on 2014 → 2015 by jim2
What number of unicorns am I keeping from “the children” Max?
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Comment on 2014 → 2015 by David in TX
Once again, weasel words and their purpose, that Joshua may understand the goal is deception not communication of contingency:
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Comment on 2014 → 2015 by jim2
Hi David W. If you check out the first link, the Congo has oil and gas, produced by … drum roll … the State Owned Oil Company. It’s this way in a lot of “poor” underdeveloped counties. It’s the thieves running the country that are the problem. And the UN does absolutely nothing for these billions of poor people. The UN should be pounding the drum for the thieves to be hanged, but the thieves are mostly in charge there. Cut off the UN, I say.
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Comment on 2014 → 2015 by Tonyb
John
From our side of the pond it would appear that many of those running for top office in the states are just not very good and it’s bivouac here not very good at an early stage.
There must surely be better contenders than Bush, Clinton or Romney ( again? Wasn’t once enough?)
The difference of course is that our royals are there by royal bloodline whereas you actually vote for the likes of Obama, the Bushes and Clinton.
I assume that the power of the political parties and money/ contacts explains why certain people get put forward but it doesn’t explain why, with the depth of Expertise you must have, why there isnt a much larger pool and why better people don’t rise to the top of the pile.
It seems to me that the States have abdicated their position as leader of the western world and that has serious repercussions for all of us and for your own power and prestige.
I don’t see the current crop of politicians having the expertise, drive or vision to reverse your relative declne. As a friend of the States I sincerely hope I am wrong.
Tonyb
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Comment on 2014 → 2015 by AK
Mining and manufacturing technology will become more and more automated dropping the cost finished goods so much that the prohibitive costs of stuff today, like solar power panels and continent spanning power grids, become inconsequential.
I tend to agree with you, which is why I strongly suspect that space solar power will have to wait until people are tired of cluttering up the landscape with collectors.
But it’s far from certain, and advances in laser technology (both solar pumped and supplied from PV/LED) may well make it cost-effective within a couple decades.
What I found most interesting was the numbers around very tall constructions. Between tensegrity construction, and materials with multi-GPa strengths (both tensile and compressive), I suspect the cost of getting materials into space will be another exponential decline. The question is, how cheap how soon can we make that tube of vacuum into space?
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